Methods for detecting mutations in the catalytic subunit of the phosphoinositol-3 kinase (PIK3CA) gene

[0001] The present invention relates to means and methods for the identification of non-responders to a HER2 inhibitor, whereby one or more mutations (mutational SNPs) in exon 9 of Phosphoinositol-3 kinase (PIK3CA) indicate non-responsiveness.

[0002] The HER family of receptor tyrosine kinases are important mediators of cell growth, differentiation and survival. The receptor family includes four distinct members including epidermal growth factor receptor (EGFR, ErbB1, or HER1), HER2 (ErbB2 or p185^neu), HER3 (ErbB3) and HER4 (ErbB4 or tyro2).

[0003] EGFR, encoded by the erbB1 gene, has been causally implicated in human malignancy. In particular, increased expression of EGFR has been observed in breast, bladder, lung, head, neck and stomach cancer as well as glioblastomas. Increased EGFR receptor expression is often associated with increased production of the EGFR ligand, transforming growth factor alpha (TGF-α), by the same tumor cells resulting in receptor activation by an autocrine stimulatory pathway. Baselga and Mendelsohn Pharmac. Ther. 64:127-154 (1994). Monoclonal antibodies directed against the EGFR or its ligands, TGF-α and EGF, have been evaluated as therapeutic agents in the treatment of such malignancies. See, e.g., Baselga and Mendelsohn., supra; Masui et al. Cancer Research 44:1002-1007 (1984); and Wu et al. J. Clin. Invest. 95:1897-1905 (1995).

[0004] The second member of the HER family, p185^neu, was originally identified as the product of the transforming gene from neuroblastomas of chemically treated rats. The activated form of the neu proto-oncogene results from a point mutation (valine to glutamic acid) in the transmembrane region of the encoded protein. Amplification of the human homolog of neu is observed in breast and ovarian cancers and correlates with a poor prognosis (Slamon et al., Science, 235:177-182 (1987); Slamon et al., Science, 244:707-712 (1989); and U.S. Pat. No. 4,968,603). To date, no point mutation analogous to that in the neu proto-oncogene has been reported for human tumors. Overexpression of HER2 (frequently but not uniformly due to gene amplification) has also been observed in other carcinomas including carcinomas of the stomach, endometrium, salivary gland, lung, kidney, colon, thyroid, pancreas and bladder. See, among others, King et al., Science, 229:974 (1985); Yokota et al., Lancet: 1:765-767 (1986); Fukushige et al., Mol Cell Biol., 6:955-958 (1986); Guerin et al., Oncogene Res., 3:21-31 (1988); Cohen et al., Oncogene, 4:81-88 (1989); Yonemura et al., Cancer Res., 51:1034 (1991); Borst et al., Gynecol. Oncol., 38:364 (1990); Weiner et al., Cancer Res., 50:421-425 (1990); Kern et al., Cancer Res., 50:5184 (1990); Park et al., Cancer Res., 49:6605 (1989); Zhau et al., Mol. Carcinog., 3:254-257 (1990); Aasland et al. Br. J. Cancer 57:358-363 (1988); Williams et al. Pathobiology 59:46-52 (1991); and McCann et al., Cancer, 65:88-92 (1990). HER2 may be overexpressed in prostate cancer (Gu et al. Cancer Lett. 99:185-9 (1996); Ross et al. Hum. Pathol. 28:827-33 (1997); Ross et al. Cancer 79:2162-70 (1997); and Sadasivan et al. J. Urol. 150:126-31 (1993)).

[0005] Antibodies directed against the rat p185^neu and human HER2 protein products have been described. Drebin and colleagues have raised antibodies against the rat neu gene product, p185^neu See, for example, Drebin et al., Cell 41:695-706 (1985); Myers et al., Meth. Enzym. 198:277-290 (1991); and WO94/22478. Drebin et al. Oncogene 2:273-277 (1988) report that mixtures of antibodies reactive with two distinct regions of p185^neu result in synergistic anti-tumor effects on neu-transformed NIH-3T3 cells implanted into nude mice. See also U.S. Pat. No. 5,824,311 issued Oct. 20, 1998.

[0006] Hudziak et al., Mol. Cell. Biol. 9(3):1165-1172 (1989) describe the generation of a panel of HER2 antibodies which were characterized using the human breast tumor cell line SK-BR-3. Relative cell proliferation of the SK-BR-3 cells following exposure to the antibodies was determined by crystal violet staining of the monolayers after 72 hours. Using this assay, maximum inhibition was obtained with the antibody called 4D5 which inhibited cellular proliferation by 56%. Other antibodies in the panel reduced cellular proliferation to a lesser extent in this assay. The antibody 4D5 was further found to sensitize HER2-overexpressing breast tumor cell lines to the cytotoxic effects of TNF-α. See also U.S. Pat. No. 5,677,171 issued Oct. 14, 1997. The HER2 antibodies discussed in Hudziak et al. are further characterized in Fendly et al. Cancer Research 50:1550-1558 (1990); Kotts et al. In Vitro 26(3):59A (1990); Sarup et al. Growth Regulation 1:72-82 (1991); Shepard et al. J. Clin. Immunol. 11(3):117-127 (1991); Kumar et al. Mol. Cell. Biol. 11(2):979-986 (1991); Lewis et al. Cancer Immunol. Immunother. 37:255-263 (1993); Pietras et al. Oncogene 9:1829-1838 (1994); Vitetta et al. Cancer Research 54:5301-5309 (1994); Sliwkowski et al. J. Biol. Chem. 269(20):14661-14665 (1994); Scott et al. J. Biol. Chem. 266:14300-5 (1991); D'souza et al. Proc. Natl. Acad. Sci. 91:7202-7206 (1994); Lewis et al. Cancer Research 56:1457-1465 (1996); and Schaefer et al. Oncogene 15:1385-1394 (1997).

[0007] A recombinant humanized version of the murine HER2 antibody 4D5 (huMAb4D5-8, rhuMAb HER2, Trastuzumab or Herceptin™; U.S. Pat. No. 5,821,337) is clinically active in patients with HER2-overexpressing metastatic breast cancers that have received extensive prior anti-cancer therapy (Baselga et al., J. Clin. Oncol. 14:737-744 (1996)). Trastuzumab received marketing approval from the Food and Drug Administration Sep. 25, 1998 for the treatment of patients with metastatic breast cancer whose tumors overexpress the HER2 protein.

[0008] Other HER2 antibodies with various properties have been described in Tagliabue et al. Int. J. Cancer 47:933-937 (1991); McKenzie et al. Oncogene 4:543-548 (1989); Maier et al. Cancer Res. 51:5361-5369 (1991); Bacus et al. Molecular Carcinogenesis 3:350-362 (1990); Stancovski et al. PNAS (USA) 88:8691-8695 (1991); Bacus et al. Cancer Research 52:2580-2589 (1992); Xu et al. Int. J. Cancer 53:401-408 (1993); WO94/00136; Kasprzyk et al. Cancer Research 52:2771-2776 (1992); Hancock et al. Cancer Res. 51:4575-4580 (1991); Shawver et al. Cancer Res. 54:1367-1373 (1994); Arteaga et al. Cancer Res. 54:3758-3765 (1994); Harwerth et al. J. Biol. Chem. 267:15160-15167 (1992); U.S. Pat. No. 5,783,186; and Klapper et al. Oncogene 14:2099-2109 (1997).

[0009] Homology screening has resulted in the identification of two other HER receptor family members; HER3 (U.S. Pat. Nos. 5,183,884 and 5,480,968 as well as Kraus et al. PNAS (USA) 86:9193-9197 (1989)) and HER4 (EP Pat. Appln. No 599,274; Plowman et al., Proc. Natl. Acad. Sci. USA, 90:1746-1750 (1993); and Plowman et al., Nature, 366:473-475 (1993)). Both of these receptors display increased expression on at least some breast cancer cell lines.

[0010] The HER receptors are generally found in various combinations in cells and heterodimerization is thought to increase the diversity of cellular responses to a variety of HER ligands (Earp et al. Breast Cancer Research and Treatment 35: 115-132 (1995)). EGFR is bound by six different ligands; epidermal growth factor (EGF), transforming growth factor alpha (TGF-α), amphiregulin, heparin binding epidermal growth factor (HB-EGF), betacellulin and epiregulin (Groenen et al. Growth Factors 11:235-257 (1994)). A family of heregulin proteins resulting from alternative splicing of a single gene are ligands for HER3 and HER4. The heregulin family includes alpha, beta and gamma heregulins (Holmes et al., Science, 256:1205-1210 (1992); U.S. Pat. No. 5,641,869; and Schaefer et al. Oncogene 15:1385-1394 (1997)); neu differentiation factors (NDFs), glial growth factors (GGFs); acetylcholine receptor inducing activity (ARIA); and sensory and motor neuron derived factor (SMDF). For a review, see Groenen et al. Growth Factors 11:235-257 (1994); Lemke, G. Molec. & Cell. Neurosci. 7:247-262 (1996) and Lee et al. Pharm. Rev. 47:51-85 (1995). Recently three additional HER ligands were identified; neuregulin-2 (NRG-2) which is reported to bind either HER3 or HER4 (Chang et al. Nature 387 509-512 (1997); and Carraway et at Nature 387:512-516 (1997)); neuregulin-3 which binds HER4 (Zhang et al. PNAS (USA) 94(18):9562-7 (1997)); and neuregulin-4 which binds HER4 (Harari et al. Oncogene 18:2681-89 (1999)) HB-EGF, betacellulin and epiregulin also bind to HER4.

[0011] While EGF and TGFα do not bind HER2, EGF stimulates EGFR and HER2 to form a heterodimer, which activates EGFR and results in transphosphorylation of HER2 in the heterodimer. Dimerization and/or transphosphorylation appears to activate the HER2 tyrosine kinase. See Earp et al., supra. Likewise, when HER3 is co-expressed with HER2, an active signaling complex is formed and antibodies directed against HER2 are capable of disrupting this complex (Sliwkowski et al., J. Biol. Chem., 269(20):14661-14665 (1994)). Additionally, the affinity of HER3 for heregulin (HRG) is increased to a higher affinity state when co-expressed with HER2. See also, Levi et al., Journal of Neuroscience 15: 1329-1340 (1995); Morrissey et al., Proc. Natl. Acad. Sci. USA 92: 1431-1435 (1995); and Lewis et al., Cancer Res., 56:1457-1465 (1996) with respect to the HER2-HER3 protein complex. HER4, like HER3, forms an active signaling complex with HER2 (Carraway and Cantley, Cell 78:5-8 (1994)).

[0012] To target the HER signaling pathway, rhuMAb 2C4 (Pertuzumab) was developed as a humanized antibody that inhibits the dimerization of HER2 with other HER receptors, thereby inhibiting ligand-driven phosphorylation and activation, and downstream activation of the RAS and AKT pathways. In a phase I trial of Pertuzumab as a single agent for treating solid tumors, 3 subjects with advanced ovarian cancer were treated with pertuzumab. One had a durable partial response, and an additional subject had stable disease for 15 weeks. Agus et al. Proc Am Soc Clin Oncol 22: 192, Abstract 771 (2003).

[0013] Also antibody variant compositions are described in the art. U.S. Pat. No. 6,339,142 describes a HER2 antibody composition comprising a mixture of anti-HER2 antibody and one or more acidic variants thereof, wherein the amount of the acidic variant(s) is less than about 25%. Trastuzumab is the exemplified HER2 antibody. Reid et al. Poster presented at Well Characterized Biotech Pharmaceuticals conference (January, 2003) “Effects of Cell Culture Process Changes on Humanized Antibody Characteristics” describes an unnamed, humanized IgG1 antibody composition with N-terminal heterogeneities due to combinations of VHS signal peptide, N-terminal glutamine, and pyroglutamic acid on the heavy chain thereof. Harris et al. “The Ideal Chromatographic Antibody Characterization Method” talk presented at the IBC Antibody Production Conference (February, 2002) reports a VHS extension on the heavy chain of E25, a humanized anti-IgE antibody. Rouse et al. Poster presented at WCBP “Glycoprotein Characterization by High Resolution Mass Spectrometry and Its Application to Biopharmaceutical Development” (Jan. 6-9, 2004) describes a monoclonal antibody composition with N-terminal heterogeneity resulting from AHS or HS signal peptide residues on the light chain thereof. In a presentation at IBC Meeting (September, 2000) “Strategic Use of Comparability Studies and Assays for Well Characterized Biologicals,” Jill Porter discussed a late-eluting form of ZENAPAX™ with three extra amino acid residues on the heavy chain thereof. US2006/0018899 describes a composition comprising a main species pertuzumab antibody and an amino-terminal leader extension variant, as well as other variant forms of the pertuzumab antibody.

[0014] Patent publications related to HER antibodies include: U.S. Pat. No. 5,677,171, U.S. Pat. No. 5,720,937, U.S. Pat. No. 5,720,954, U.S. Pat. No. 5,725,856, U.S. Pat. No. 5,770,195, U.S. Pat. No. 5,772,997, U.S. Pat. No. 6,165,464, U.S. Pat. No. 6,387,371, U.S. Pat. No. 6,399,063, US2002/0192211A1, U.S. Pat. No. 6,015,567, U.S. Pat. No. 6,333,169, U.S. Pat. No. 4,968,603, U.S. Pat. No. 5,821,337, U.S. Pat. No. 6,054,297, U.S. Pat. No. 6,407,213, U.S. Pat. No. 6,719,971, U.S. Pat. No. 6,800,738, US2004/0236078A1, U.S. Pat. No. 5,648,237, U.S. Pat. No. 6,267,958, U.S. Pat. No. 6,685,940, U.S. Pat. No. 6,821,515, WO98/17797, U.S. Pat. No. 6,127,526, U.S. Pat. No. 6,333,398, U.S. Pat. No. 6,797,814, U.S. Pat. No. 6,339,142, U.S. Pat. No. 6,417,335, U.S. Pat. No. 6,489,447, WO99/31140, US2003/0147884A1, US2003/0170234A1, US2005/0002928A1, U.S. Pat. No. 6,573,043, US2003/0152987A1, WO99/48527, US2002/0141993A1, WO01/00245, US2003/0086924, US2004/0013667A1, WO00/69460, WO01/00238, WO01/15730, U.S. Pat. No. 6,627,196B1, U.S. Pat. No. 6,632,979B1, WO01/00244, US2002/0090662A1, WO01/89566, US2002/0064785, US2003/0134344, WO 04/24866, US2004/0082047, US2003/0175845A1, WO03/087131, US2003/0228663, WO2004/008099A2, US2004/0106161, WO2004/048525, US2004/0258685A1, U.S. Pat. No. 5,985,553, U.S. Pat. No. 5,747,261, U.S. Pat. No. 4,935,341, U.S. Pat. No. 5,401,638, U.S. Pat. No. 5,604,107, WO 87/07646, WO 89/10412, WO 91/05264, EP 412,116 B1, EP 494,135 B1, U.S. Pat. No. 5,824,311, EP 444,181 B1, EP 1,006,194 A2, US 2002/0155527A1, WO 91/02062, U.S. Pat. No. 5,571,894, U.S. Pat. No. 5,939,531, EP 502,812 B1, WO 93/03741, EP 554,441 B1, EP 656,367 A1, U.S. Pat. No. 5,288,477, U.S. Pat. No. 5,514,554, U.S. Pat. No. 5,587,458, WO 93/12220, WO 93/16185, U.S. Pat. No. 5,877,305, WO 93/21319, WO 93/21232, U.S. Pat. No. 5,856,089, WO 94/22478, U.S. Pat. No. 5,910,486, U.S. Pat. No. 6,028,059, WO 96/07321, U.S. Pat. No. 5,804,396, U.S. Pat. No. 5,846,749, EP 711,565, WO 96/16673, U.S. Pat. No. 5,783,404, U.S. Pat. No. 5,977,322, U.S. Pat. No. 6,512,097, WO 97/00271, U.S. Pat. No. 6,270,765, U.S. Pat. No. 6,395,272, U.S. Pat. No. 5,837,243, WO 96/40789, U.S. Pat. No. 5,783,186, U.S. Pat. No. 6,458,356, WO 97/20858, WO 97/38731, U.S. Pat. No. 6,214,388, U.S. Pat. No. 5,925,519, WO 98/02463, U.S. Pat. No. 5,922,845, WO 98/18489, WO 98/33914, U.S. Pat. No. 5,994,071, WO 98/45479, U.S. Pat. No. 6,358,682 B1, US 2003/0059790, WO 99/55367, WO 01/20033, US 2002/0076695 A1, WO 00/78347, WO 01/09187, WO 01/21192, WO 01/32155, WO 01/53354, WO 01/56604, WO 01/76630, WO02/05791, WO 02/11677, U.S. Pat. No. 6,582,919, US2002/0192652A1, US 2003/0211530A1, WO 02/44413, US 2002/0142328, U.S. Pat. No. 6,602,670 B2, WO 02/45653, WO 02/055106, US 2003/0152572, US 2003/0165840, WO 02/087619, WO 03/006509, WO03/012072, WO 03/028638, US 2003/0068318, WO 03/041736, EP 1,357,132, US 2003/0202973, US 2004/0138160, U.S. Pat. No. 5,705,157, U.S. Pat. No. 6,123,939, EP 616,812 B1, US 2003/0103973, US 2003/0108545, U.S. Pat. No. 6,403,630 B1, WO 00/61145, WO 00/61185, U.S. Pat. No. 6,333,348 B1, WO 01/05425, WO 01/64246, US 2003/0022918, US 2002/0051785 A1, U.S. Pat. No. 6,767,541, WO 01/76586, US 2003/0144252, WO 01/87336, US 2002/0031515 A1, WO 01/87334, WO 02/05791, WO 02/09754, US 2003/0157097, US 2002/0076408, WO 02/055106, WO 02/070008, WO 02/089842 and WO 03/86467.

[0015] Patients treated with the HER2 antibody Trastuzumab/Herceptin™ are selected for therapy based on HER2 protein overexpression/gene amplification; see, for example, WO99/31140 (Paton et al.), US2003/0170234A1 (Hellmann, S.), and US2003/0147884 (Paton et al.); as well as WO01/89566, US2002/0064785, and US2003/0134344 (Mass et al.). See, also, US2003/0152987, Cohen et al., concerning immunohistochemistry (IHC) and fluorescence in situ hybridization (FISH) for detecting HER2 overexpression and amplification. WO2004/053497 and US2004/024815A1 (Bacus et al.), as well as US 2003/0190689 (Crosby and Smith), refer to determining or predicting response to Trastuzumab therapy. US2004/013297A1 (Bacus et al.) concerns determining or predicting response to ABX0303 EGFR antibody therapy. WO2004/000094 (Bacus et al.) is directed to determining response to GW572016, a small molecule, EGFR-HER2 tyrosine kinase inhibitor. WO2004/063709, Amler et al., refers to biomarkers and methods for determining sensitivity to EGFR inhibitor, erlotinib HCl. US2004/0209290, Cobleigh et al., concerns gene expression markers for breast cancer prognosis.

[0016] Patients treated with pertuzumab (a HER2 dimerisation inhibitor described herein below in more detail) can be selected for therapy based on HER activation or dimerization. Patent publications concerning pertuzumab and selection of patients for therapy therewith include: WO01/00245 (Adams et al.); US2003/0086924 (Sliwkowski, M.); US2004/0013667A1 (Sliwkowski, M.); as well as WO2004/008099A2, and US2004/0106161 (Bossenmaier et al.).

[0017] Herceptin™/Trastuzumab is indicated in the art for the treatment of patients with metastatic breast cancer whose tumors overexpress HER2 protein or have HER 2 gene amplification:

[0018] a) As monotherapy for the treatment of those patients who have received at least two chemotherapy regimens for their metastatic disease. Prior chemotherapy must have included at least an anthracycline and a taxane unless patients are unsuitable for these treatments. Hormone receptor positive patients must also have received hormonal therapy, unless patients are unsuitable for these treatments,

[0019] b) In combination with paclitaxel for the treatment of those patients who have not received chemotherapy for their metastatic disease and for whom an anthracycline is not suitable and

[0020] c) In combination with docetaxel for the treatment of those patients who have not received chemotherapy for their metastatic disease.

[0021] Herceptin™/Trastuzumab can also be used as adjuvant treatment in early breast cancer. Herceptin™/Trastuzumab is also approved for the treatment of patients with HER2-positive early breast cancer following surgery, chemotherapy (neoadjuvant (i.e. before surgery) or adjuvant), and radiotherapy (if applicable). In addition Herceptin in combination with capecitabine or 5-fluorouracil and cisplatin is indicated for the treatment of patients with HER2 positive locally advance or metastatic adenocarcinoma of the stomach or gastroesophageal junction who have not received prior anti-cancer treatment for their metastatic disease.

[0022] In the art, the treatment of breast cancer patients with Herceptin™/Trastuzumab is, for example, recommended and routine for patients having HER2-positive cancer. HER2-positive cancer is present if a high HER2 (protein) expression level detected by immunohistochemical methods (e.g. HER2 (+++)) or HER2 gene amplification detected by in-situ-hybridization (e.g. ISH positive, like a HER2 gene copy number higher than 4 copies of the HER2 gene per tumor cell or ratio of ≧2.0 for the number of HER2 gene copies to the number of signals for CEP17.) or both is found in samples obtained from the patients such as breast tissue biopsies or breast tissue resections or in tissue derived from metastatic sites.

[0023] The NEOSPHERE study (Neoadjuvant Study of Pertuzumab and Herceptin in an Early Regimen Evaluation) is a randomized multicentre, international Phase II study that was conducted in 78 centres worldwide (except the USA) in 417 women with newly diagnosed HER2-positive early, inflammatory or locally advanced breast cancer who had never received Herceptin. Prior to surgery (neoadjuvant treatment) these women were randomized to four study arms. The primary endpoint was complete tumour disappearance at time of surgery (pathological complete response, pCR) and the results were:

[0024] pCR of 29.0 percent for Herceptin and docetaxel

[0025] pCR of 45.8 percent for Herceptin, pertuzumab and docetaxel

[0026] pCR of 16.8 percent for Herceptin and pertuzumab

[0027] pCR of 24.0 percent for pertuzumab and docetaxel

[0028] The data shows that the two antibodies plus docetaxel given in the neoadjuvant setting prior to surgery significantly improved the rate of complete tumour disappearance (pathological complete response rate, pCR, of 45.8 percent) in the breast by more than half compared to Herceptin plus docetaxel (pCR of 29.0 percent), p=0.014. The study is described in detail e.g. in Lancet Oncol. 2012 January; 13(1):25-32. doi: 10.1016/S1470-2045(11)70336-9. Epub 2011 Dec. 6, which is incorporated by reference herein in its entirety. Core biopsies (tumor tissue) from 387 patients were used for biomarker analyses.

[0029] However, not all patients having HER2-positive cancer or cancer cells respond to treatment with a HER2 inhibitor. Therefore, efforts have been made in the art to identify non-responding patients that may be excluded from treatment. Barbereschi (Clin Cancer Res 2007, 13:6064-6069) investigated the association of phosphoinositide-3-kinase, catalytic, alpha polypeptide (PIK3CA) mutations on exon 9 and 20 with pathologic features and clinical outcome in breast cancer patients treated with chemotherapy and/or hormone therapy. Berns (Cancer Cell (2007) 12, 395-402) describes that the presence of PIK3CA mutations (inter alia in exon 9 and 20) was associated with poor prognosis after trastuzumab therapy. Also Razis (Breast Cancer Res Treat (DOI 10.1007/s10549-011-1572-5) investigates the association of PIK3CA mutations (in exon 9 and 20) with efficacy of trastuzumab therapy and describes that these mutations were associated with shorter median time to progression. Dave (2011, J Clinical Oncology 29, 166) also find that activating mutations in the PIK3CA conferred resistance to Trastuzumab.

[0030] Thus, the technical problem underlying the present invention is the provision of means and methods for identifying a patient or a group of patients with HER2-positive cancer who are non-responsive to a treatment with a HER2 inhibitor, in particular to a treatment with a HER2 antibody such as Trastuzumab or Pertuzumab.

[0031] The technical problem is solved by provision of the embodiments characterized in the claims.

[0032] Accordingly, the present invention relates to a method for identifying a non-responder to a HER2-inhibitor, said method comprising evaluating the presence of one or more mutations in exon 9 of the catalytic subunit of Phosphoinositol-3 kinase (PIK3CA or p110α) in a sample from a patient with HER2-positive cancer; and whereby the presence of one or more mutations in exon 9 indicates non-responsiveness of said patient to said HER2 inhibitor.

[0033] In the present invention, it was surprisingly found that mutations in exon 9 of Phosphoinositol-3 kinase (PIK3CA) are indicative for non-responsiveness of a patient with HER2-positive cancer to a HER2 inhibitor, such as Trastuzumab and, in particular Pertuzumab. In contrast, as found herein, mutations in exon 20 were not predictive for non-responsiveness. In other words, it was unexpectedly found that the evaluation only of mutations in exon 9 of Phosphoinositol-3 kinase (PIK3CA) is sufficient for a highly reliable determination of non-responders to treatment with HER2 inhibitors, in particular anti-HER2 antibodies. Therefore, exon 9 mutations are, preferably, the only PIK3CA mutations evaluated in the methods of the present invention. In accordance with the invention, solely the presence of mutations in exon 9 of PIK3CA is determined/evaluated/measured, i.e. the presence of mutations in other parts (e.g. like exon 20) of the PIK3CA gene or coding sequence are not evaluated or determined. The invention is, thus, based on the surprising finding that the determination/evaluation of solely (only) mutations (like mutational SNPs) in exon 9 of PIK3CA is enough for a reliable read-out whether a patient will or will not respond to treatment with a HER2 inhibitor. The evaluation of such mutations and/or SNPs is described herein below in more detail and exemplified in the examples. None of the documents discussed above discloses or proposes the use of only (solely) PIK3CA mutations (or mutational SNPs) in exon 9 for identifying non-responders to therapy with HER2 inhibitors.

[0034] Exemplary mutations/SNPs in exon 9 of PIK3CA that can be determined/evaluated in the herein provided method for identification of non-responders to HER2-inhibitors are those where the mutation results in a change in the amino acid sequence at position 542 and 545 of the full length protein sequence of PIK3CA as shown in SEQ ID NO: 2. In the wild-type protein sequence of PIK3CA the amino acid at position 542 and 545 is “E”. In the mutant forms of PIK3CA to be determined herein, the wild type “E” at these positions is replaced by the amino acid “K” (“E542K” or “E545K”), amino acid “A” (“E545A”) or amino acid “G” (“E545G”). These changes at amino acid level are also reflected in mutations at the nucleic acid level (like mutational SNPs) and corresponding mutated triplets (codons) to be determined/detected/evaluated are given herein further below.

[0035] The non-responders identified by the herein provided means and methods may be subject to other treatments than treatment with a HER2 inhibitor; for example, they may advantageously be treated with compounds other than HER2 inhibitors. The term “non-responder” as used herein can refer to an individual/patient/subject that is less likely to respond to a treatment using a HER2 inhibitor (like pertuzumab or trastuzumab). “Less likely to respond” as used herein refers to a decreased likeliness that a pathological complete response (pcR) will occur in a patient treated with a HER2 inhibitor. In cases where (with the methods of the present invention) it was assessed that the subject is a “non-responder” or is “less likely to respond”, said subject is to receive phosphoinositol-3 kinase-targeted agents. Such agents are known in the art and comprise, but are not limited to fused pyrimidine derivatives as disclosed in U.S. Pat. No. 8,022,205 B2 or fused pyrrolopyrimidine derivatives as disclosed in WO2009/099163.

[0036] The sample to be evaluated can be obtained from a patient with HER2-positive cancer. The HER2-positive cancer may assessed be breast cancer, such as early-stage breast cancer. However, the method of identifying non-responders provided herein can be applied to a wide range of HER2-positive cancers, like gastric cancer, colon cancer, lung cancer and the like. In a preferred embodiment, the HER2 inhibitor is an anti-HER2 antibody, like pertuzumab or trastuzumab. Preferably, the patient is a human.

[0037] Accordingly, this invention relates to a method for identifying a non-responder to a HER2-inhibitor, said method comprising detecting/measuring the presence of one or more mutations in exon 9 of the catalytic subunit of Phosphoinositol-3 kinase (PIK3CA or p110α) in a sample from a patient with HER2-positive cancer; and whereby the presence of one or more mutations in exon 9 indicates non-responsiveness of said patient to said HER2 inhibitor.

[0038] The present invention relates to a method for identifying a non-responder to a HER2-inhibitor, said method comprising the steps

[0039] (a) obtaining a sample from a patient with HER2-positive cancer;

[0040] (b) evaluating the presence of one or more mutations in exon 9 of the catalytic subunit of Phosphoinositol-3 kinase (PIK3CA or p110α) in said sample;

whereby the presence of one or more mutations in exon 9 of the catalytic subunit of Phosphoinositol-3 kinase (PIK3CA or p110α) indicates non-responsiveness of said patient to said HER2 inhibitor.

[0041] As mentioned, it has been found herein that the presence of one or more mutations in exon 9 of the catalytic subunit of PI3K i.e. PIK3CA indicates non-responsiveness to a HER2 inhibitor. The following provides some background information on PIK3CA and the family of Phosphatidylinositol 3-kinase to which it belongs; the mutations in exon 9 of the catalytic subunit of PI3K are explained in more detail further below. The mutation may be the replacement or exchange (substitution) of one or more amino acids as compared to the wild-type sequence of exon 9 of Phosphoinositol-3 kinase catalytic subunit (PIK3CA).

[0042] Corresponding nucleic acid sequences and amino acid sequences of wild-type PIK3CA are shown in SEQ ID NO. 1 and SEQ ID NO: 2, respectively, and in FIG. 7. As used herein, the term “PIK3CA” refers to the catalytic subunit of Phosphoinositol-3 kinase (PI3K), isoform alpha, also referred to as p110alpha. The terms “PIK3CA”, “catalytic subunit of Phosphoinositol-3 kinase isoform alpha” or, short, “p110alpha”/“p110α” are used interchangeably herein. “PIK3CA” is the term recommended and commonly used in the art; however, the entire protein is also known as PI3K. Phosphatidylinositol 3-kinase (PI3K) is composed of an 85 kDa regulatory subunit and a 110 kDa catalytic subunit. The protein encoded by the PIK3CA gene represents the catalytic subunit of PI3K, which uses ATP to phosphorylate PtdIns, PtdIns4P and PtdIns(4,5)P2 (i.e. this catalytic subunit is “PIK3CA” as defined and used herein). This gene has been found to be oncogenic and has been implicated in a variety of cancers.

[0043] Phosphoinositol-3 kinase belongs to the family of Phosphatidylinositol 3-kinases (PI 3-kinases or “PI3Ks”). This is a family of enzymes involved in cellular functions such as cell growth, proliferation, differentiation, motility, survival and intracellular trafficking, which in turn are involved in cancer. In response to lipopolysaccharide, PI3Ks phosphorylate p65, inducing anandamide synthesis to inhibit NF-κB activation. This is under the control of FAAH limiting the ability of LPS to increase AEA levels and is also inhibited by wortmannin and cannabidiol, one of the only natural compounds to inhibit FAAH. The phosphoinositol-3-kinase family is divided into three different classes: Class I, Class II, and Class III. The classifications are based on primary structure, regulation, and in vitro lipid substrate specificity.

[0044] The following table provides an overview of the human genes/proteins of Phosphatidylinositol 3-kinases family members. PIK3CA is highlighted in bold.

[0045]

group	gene	protein	synonyms
class 2	PIK3C2A	PI3K, class 2, alpha polypeptide	PI3K-C2α
	PIK3C2B	PI3K, class 2, beta polypeptide	PI3K-C2β
	PIK3C2G	PI3K, class 2, gamma polypeptide	PI3K-C2γ
class 3	PIK3C3	PI3K, class 3	Vps34
class 1	PIK3CA	PI3K, catalytic, alpha polypeptide	p110-α
catalytic	PIK3CB	PI3K, catalytic, beta polypeptide	p110-β
	PIK3CG	PI3K, catalytic, gamma polypeptide	p110-γ
	PIK3CD	PI3K, catalytic, delta polypeptide	p110-γ
class 1	PIK3R1	PI3K, regulatory subunit 1 (alpha)	p85-α
regulatory	PIK1R2	PI3K, regulatory subunit 2 (beta)	p85β
	PIK3R3	PI3K, regulatory subunit 3 (gamma)	p55-γ
	PIK3R4	PI3K, regulatory subunit 4	p150
	PIK3R5	PI3K, regulatory subunit 5	p101
	PIK3R5	PI3K, regulatory subunit 6	p87

PIK3CA and its genetic variants to be used in the herein provided methods for identifying non-responders to HER2-inhibitors and their use in screening methods for responsiveness to treatment with a compound are described, for example, in WO 2011/031861, WO 2005/091849 and WO 2011/060380.

[0046] In context of the present invention, the mutation (mutational SNP) to be determined/assessed in accordance with the present invention may be a mutation in the codon encoding an amino acid at position 542 and/or 545 of the full-length amino acid sequence of Phosphatidylinositol-3 kinase (PIK3CA) (see e.g. SEQ ID NO. 2 of FIG. 7). The mutation may comprise one or more of the mutations E542K, E545K, E545A and E545G (i.e. mutations/SNP in exon 9 encoding the amino acid K, A or G at position 542 or 545 of the amino acid sequence of Phosphatidylinositol-3 kinase (PIK3CA) instead of wildtype E. The term E542K, E545K, E545A and E545G as used herein refer to amino acid substitutions at a given position of the amino acid sequence of wild type PIK3CA. Corresponding nucleic acid sequences (codons/triplets) encoding the amino acid at positions 542 and 545 in wild type and mutant PIK3CA genes/coding sequences are described below. In accordance with internationally accepted nomenclature, the term “E542K” refers to a substitution/replacement of amino acid “E” at position 542 of the amino acid sequence of wild type PIK3CA by amino acid “K”. The same explanation applies, mutatis mutandis, to “E545K”, “E545A” and “E545G”. These mutations are well known in the art and corresponding mutated sequences can be retrieved from the respective databases like Uniprot. Based on the herein provided teaching, the presence of these mutations can readily be determined by a person skilled in the art. Preferably, the mutation is determined on a nucleic acid level as described below and exemplified in the examples. The mutations E542K E545K, E545A and E545G are also illustrated in the herein described sequences. For example, nucleic acid and amino acid sequences of mutation (mutational SNP) E542K are shown in SEQ ID NO. 17 and SEQ ID NO. 18, respectively; nucleic acid and amino acid sequences of mutation E545K are shown in SEQ ID NO: 19 and SEQ ID NO. 20, respectively; nucleic acid and amino acid sequences of mutation E545A are shown in SEQ ID NO: 21 and SEQ ID NO. 22, respectively, and nucleic acid and amino acid sequences of mutation E545G are shown in SEQ ID NO: 23 and SEQ ID NO. 24, respectively.

[0047] Methods for the determining/evaluation assessed/measured of the presence of the mutations are described herein and provided in the examples. Exemplary, non-limiting methods to be used are methods for sequencing of nucleic acids (e.g. Sanger di-deoxy sequencing), “next generation” sequencing methods, single molecule sequencing, methods enabling detection variant alleles/mutations, such as Real-time PCR, PCR-RFLP assay (see Cancer Research 59 (1999), 5169-5175), mass-spectrometric genotyping (e.g. MALDI-TOF), HPLC, enzymatic methods and SSPC (single strand conformation polymorphism analysis; see Pathol Int (1996) 46, 801-804).

[0048] Such methods may include enzymatic amplification of DNA or cDNA fragments using oligonucleotides specifically hybridizing to exon 9 (or parts thereof) of the PIK3CA gene by PCR. Given that mutations in exon 9 of the PIK3CA gene are to be evaluated, such amplifications may be carried out in one or two reactions when employing RNA or genomic DNA. The resulting PCR products may be subjected to either conventional Sanger-based dideoxy nucleotide sequencing methods or employing parallel sequencing methods (“next generation sequencing”) such as those marketed by Roche (454 technology), Illumina (Solexa technology) or ABI (Solid technology). Mutations may be identified from sequence reads by comparison with publicly available gene sequence data bases. Alternatively, mutations may be identified by incorporation of allele-specific probes that can either be detected using enzymatic detection reactions, fluorescence, mass spectrometry or others; see Vogeser (2007) Dtsch Arztebl 104 (31-32), A2194-200.

[0049] Paraffin-embedded clinical material as well as fresh frozen tissue may be used in the detection of these mutations. Detection may comprise a histolopathology review of the sample to be tested to see whether tumour tissue is present. The following table shows exemplary nucleic acid sequences of the mutations (mutational SNPs) to be determined in accordance with the present invention; any other point mutation(s) that result in an amino acid change at position 542 and/or 545 (or position 546, like the E545D mutation having the sequence “gat”/“T” mutation”) of full-length the amino acid sequence of PIK3CA can be included in the assessment in accordance with the present invention.

[0050]

	gaa	codonitripiet encoding wild type E542
	gag	codon/tripiet encoding wild type E545
	aaa	codonitripiet encoding mutant E542K ((E >> K)
	aag	codon/tripiet encoding mutant E545K (E >> K),
	gcg	codon/triplet encoding mutant E545A (E >> A),
	ggg	I codon/triplet encoding mutant E545G(E >> G),

[0051] Accordingly, the term “mutation E542K in exon 9 of Phosphoinositol-3 kinase (PIK3CA)” as used herein may refer to a codon/triplet (like aaa) encoding amino acid K at position 542 of the full-length amino acid sequence of PIK3CA (the wild-type sequence thereof is shown in FIG. 7 and SEQ ID NO: 2). The term “mutation E545K in exon 9 of Phosphoinositol-3 kinase (PIK3CA)” as used herein may refer to a codon/triplet (like aag) encoding amino acid K at position 545 of the full-length amino acid sequence of PIK3CA (the wild-type sequence thereof is shown in FIG. 7 and SEQ ID NO: 2). The term “mutation E545A in exon 9 of Phosphoinositol-3 kinase (PIK3CA)” as used herein may refer to a codon/triplet (like gcg) encoding amino acid A at position 545 of the full-length amino acid sequence of PIK3CA (the wild-type sequence thereof is shown in FIG. 7 and SEQ ID NO: 2). The term “mutation E545G in exon 9 of Phosphoinositol-3 kinase (PIK3CA)” as used herein may refer to a codon/triplet (like ggg) encoding amino acid G at position 545 of the full-length amino acid sequence of PIK3CA (the wild-type sequence thereof is shown in FIG. 7 and SEQ ID NO: 2).

[0052] The following exemplary test may be used.

[0053] The PCR amplification of isolated DNA and mutation detection procedures for the PIK3CA mutation detection test are summarized below.

[0054] Each standard 50-4 amplification reaction targeting one of the Exons 7, 9 or 20 included 100 ng genomic DNA, dNTPs (including dUTP), 0.05 U/μL Z05, DNA polymerase, 0.04 U/μL uracil-DNA glycosylase (UNG), and 200-400 nM forward and reverse primer (Table 1), 75-200 nM mutant and wild-type specific probes (Table 2). Amplification was performed in the Cobas® 4800 analyzer using the following temperature profile: 5 min at 50° C. followed by 55 cycles of 95° C. for 10 sec and 63° C. for 50 sec, followed by a single round of 40° C. for 2 min and 25° C. for 10 sec (melting curve analysis). Fluorescence data was collected during each amplification cycle and during the final melting curve analysis.

[0055] The following exemplary primers/primer pair may be used in the method for identifying a non-responder to a HER2-inhibitor provided herein, wherein the non-responder has a mutation in exon 9 of PIK3CA.

[0056]

TABLE 1
Primer Sequences for the
PIK3CA Mutation Detection Test
	Primer	Sequence 5′ to 3′
	542/545	UAAAAUUUAUUGAGAAUGUAUUUG
	Forward primer	CTTTTTC (SEQ ID NO: 25)
	PIK3CA-9F13
	542/545	TCCATTTTAGCACTTACCTGTGAC
	Reverse primer	(SEQ ID NO: 26)
	PIK3CA-9R01
	Key:
	U = 5-propynyl dU

[0057] The following exemplary probes may be used in the method for identifying a non-responder to a HER2-inhibitor provided herein, wherein the non-responder has a mutation in exon 9 of PIK3 CA.

[0058]

TABLE 2
Probe Sequences for the PIK3CA Mutation Detection Test
Probe	Sequence 5′ to 3′
542 WT Probe	FTTTCAQAGAGAGGAUEUEGUGUAGAAAUUGEP (SEQ ID NO: 27)
542 542K Mutation Probe	LATTTTQGAGAGAGGAUEUEGUGUAGAAAUUGEUUP (SEQ ID NO: 28)
545 WT Probe	OCTGCTCAGTQAUUUIAGAGAGAGGATCTCGTGTP (SEQ ID NO: 29)
545 545K Mutation Probe	JAATCACTAAGQAGGAGAAAGAUUUUEUAUGGAGUEP (SEQ ID NO: 30)
545 545A Mutation Probe	FCTGCGCQGGAGAAAGAUUUUEUAUGGAGUEAP (SEQ ID NO: 31)
545 545G Mutation Probe	LCCTGCCCQGTGAUUUIAGAGAGAGGATCTCGP (SEQ ID NO: 32)
Key:
F = FAM Reporter Dye , J = JA270 Reporter Dye, 0 = CY5.5 Reporter Dye, L = HEX Reporter Dye, U = 5-propynyl dU, E = 5-methyl dC,, I = deoxyinosine, Z = 7-deaza dG, Q = BHQ2 Quencher Dye, P = 3′ Phosphate

[0059] In accordance with the present invention, the presence of one or more mutations in exon 9 of PIK3CA may be evaluated/determined/measured in the herein provided method for identifying a non-responder to HER2 inhibitors (the terms “evaluating”, “determining” and “measuring” can be used interchangeably in context of the present invention). In one embodiment, the presence of only one of the mutations is evaluated/determined. Accordingly, the presence of only one of the E542K, E545K, E545A and E545G mutations of PIK3CA (i.e. the nucleic acids in exon 9 of PIK3CA encoding the amino acid at these positions in the full length amino acid sequence of PIK3CA) may be evaluated, i.e. only E542K, only E545K, only E545A or only E545G. The methods of the present invention may also comprise the subsequent evaluation of the presence of two or more of these mutations in any order. For example, the evaluation of the presence of E542K may be followed by the evaluation of E545K (or vice versa) which may be followed by the evaluation of the presence of E545A, which may be followed by the evaluation of the presence of E545G. Other possible orders of evaluation are easily conceivable by a person skilled in the art and contemplated herein.

[0060] The mutations may be evaluated in combination/simultaneously. Again, any combination is envisaged. For example, the presence of E542K and E545K is evaluated; or the presence of E542K and E545A; or the presence of E542K and E545G is evaluated. Other combinations are easily conceivable. The evaluation of a combination of these mutations may be followed or preceded by the evaluation of the presence of one other mutation or a combination of other mutations.

[0061] As mentioned, the present invention provides for means to determine whether an individual/patient with HER2-positive cancer (i.e. suffering from, suspected to suffer from or being prone to suffer from HER2-positive cancer) will respond to treatment with a HER2 inhibitor or will not respond to treatment to a HER2 inhibitor. This assessment may be advantageously done before the start of treatment with the HER2 inhibitor. Even if a patient has been treated with a HER2 inhibitor, a person skilled in the art can determine whether a person showed no response after the treatment with the HER2 inhibitor. For example, a non-response to an inhibitor may be reflected in an increased suffering from cancer, such as an increased growth of a cancer/tumor and/or increase in the size of a tumor, the (increase in) the formation of metastases or a increase in the number or size of metastases. A non-response may also be the development of a tumor or metastases, for example after resection of a tumor, in the shortening of time to disease progression, or in the increase in the size of (a) tumor(s) and/or (a) metastases, for example in neoadjuvant therapy.

[0062] In accordance with the methods provided in the present invention a patient group can be identified that does not respond to treatment with HER2 inhibitors, like Pertuzumab or Trastuzumab. It has been found herein that some individuals with HER2 positive cancer or cancer cells do not adequately respond to treatment with a HER2 inhibitor, if the patients have mutations in exon 9 of PIK3CA. In one embodiment of the present invention, at least 80%, 90%, 95% or more of the patient group identified by the herein provided method do not respond to treatment with a HER2 inhibitor. That means that at least 80% of the identified individuals having the herein described mutation(s) in exon 9 of PIK3CA will not respond to the treatment with the herein defined HER2 inhibitors, like Pertuzumab or Trastuzumab.

[0063] As the skilled artisan fully appreciates a positive test for one or more mutations in exon 9 of PIK3CA in a sample of a patient with HER2-positive cancer does not indicate that the patient will not respond to treatment with absolute certainty. However, by the herein provided methods sub-groups of patients are identified that have a lower chance of response (=show a lower response rate) to a treatment with a HER2 inhibitor like pertuzumab or trastuzumab as compared to the sub-groups of patients not having these mutations in exon 9 of PIK3CA. With other words the determination of a presence of one or more mutations in exon 9 of PIK3CA indicates (=is indicative for) that the patient has a lower chance (=probability, likelihood) to respond to treatment with a HER2 inhibitor, as compared to a patient having no mutation in exon 9 of PIK3CA (wild type PIK3CA). Preferably, the response is pathologic complete response (pCR). The term “pCR” as used herein refers to the absence of invasive cancer cells in tissue like breast tissue or absence of invasive tumor cells in tissue like breast tissue and/or lymph nodes. pCR is commonly used as an endpoint in neoadjuvant treatment such as in breast cancer treatment.

[0064] The term “HER2-positive cancer” as used herein refers to a cancer/tumorous tissue etc. which comprises cancer cells which have higher than normal levels of HER2. Examples of HER2-positive cancer include HER2-positive breast cancer and HER2-positive gastric cancer. For the purpose of the present invention, “HER2-positive cancer” has an immunohistochemistry (IHC) score of at least 2+ and/or an in situ hybridization (ISH) amplification ratio ≧2.0 (i.e. is ISH-positive). Accordingly, HER2-positive cancer is present if a high HER2 (protein) expression level detected e.g. by immunohistochemical methods and/or HER2 gene amplification detected by in-situ-hybridization (ISH positive, like a HER2 gene copy number higher than 4 copies of the HER2 gene per tumor cell or ratio of ≧2.0 for the number of HER2 gene copies to the number of signals for CEP17.) is found in samples obtained from the patients such as breast tissue biopsies or breast tissue resections or in tissue derived from metastatic sites. In one embodiment “HER2-positive cancer” has an immunohistochemistry (IHC) score of HER2(3+) and/or is ISH positive.

[0065] The expression level of HER2 may be detected by an immunohistochemical method, whereas said HER2 gene amplification status can be measured with in situ hybridization methods, like fluorescence in situ hybridization techniques (FISH). Corresponding assays and kits are well known in the art, for protein expression assays as well as for the detection of gene amplifications. Alternatively other methods like qRT-PCR might be used to detect levels of HER2 gene expression.

[0066] The expression level of HER2 can, inter alia, be detected by an immunohistochemical method. Such methods are well known in the art and corresponding commercial kits are available. Exemplary kits which may be used in accordance with the present invention are, inter alia, HerceptTest™ produced and distributed by the company Dako or the test called Ventana Pathway™. The level of HER2 protein expression may be assessed by using the reagents provided with and following the protocol of the Herceplest™. A skilled person will be aware of further means and methods for determining the expression level of HER2 by immunohistochemical methods; see for example WO 2005/117553. Therefore, the expression level of HER2 can be easily and reproducibly determined by a person skilled in the art without undue burden. However, to ensure accurate and reproducible results, the testing must be performed in a specialized laboratory, which can ensure validation of the testing procedures.

[0067] The expression level of HER2 can be classified in a low expression level, an intermediate expression level and a high expression level. It is preferred in context of this invention that HER2-positive disease is defined by a strong expression level of HER2 (e.g. HER2(3+) by IHC), for example determined in a sample of a cancer patient.

[0068] The recommended scoring system to evaluate the IHC staining patterns which reflect the expression levels of HER2 designated herein HER2(0), HER2(+), HER2(++) and HER2(+++), is as follows:

[0069]

Staining		HER2
Intensity		overexpression
Score	Staining Pattern	assessment
0	No staining is observed or	negative
	membrane staining is observed in <10%
	of the tumor cells
1+	A faint/barely perceptible membrane	negative
	staining is detected in >10% of the tumor
	cells. The cells are only
	stained in part of their membrane.
2+	A weak to moderate complete staining is	weak to moderate
	detected in >10% of the tumor cells.	overexpression.
3+	A strong complete membrane staining is	strong
	detected in >10% of the tumor cells.	overexpression.

[0070] The terms HER2(+), HER2(++) and HER2(+++) used herein are equivalent to the terms HER2(1+), HER2(2+) and HER2(3+). A “low protein expression level” used in context of this invention corresponds to a 0 or 1+ score (“negative assessment” according to the table shown herein above), an “weak to moderate protein expression level” corresponds to a 2+ score (“weak to moderate overexpression”, see the table above) and a “high protein expression level” corresponds to a 3+ score (“strong overexpression”, see the table above). As described herein above in detail, the evaluation of the protein expression level (i.e. the scoring system as shown in the table) is based on results obtained by immunohistochemical methods. As a standard or routinely, the HER-2 status is, accordingly, performed by immunohistochemistry with one of two FDA-approved commercial kits available; namely the Dako Herceptest™ and the Ventana Pathway™. These are semi-quantitative assays which stratify expression levels into 0 (<20,000 receptors per cell, no expression visible by IHC staining), 1+ (˜100,000 receptors per cell, partial membrane staining, <10% of cells overexpressing HER-2), 2+ (˜500,000 receptors per cell, light to moderate complete membrane staining, >10% of cells overexpressing HER-2), and 3+ (˜2,000,000 receptors per cell, strong complete membrane staining, >10% of cells overexpressing HER-2).

[0071] Alternatively, further methods for the evaluation of the protein expression level of HER2 may be used, e.g. Western Blots, ELISA-based detection systems and so on.

[0072] A HER2-positive cancer may also be diagnosed by assessing the gene amplification status of HER2. HER2-positive cancer is, accordingly, diagnosed if this assessment by ISH is positive. In accordance with this assessment, a HER2-positive cancer may, inter alia, relate to an average HER2 gene copy number higher than 4 copies of the HER2 gene per tumor cell (for those test systems without an internal centromere control probe) or to a HER2/CEP17 ratio of >=2.0 (for those test systems using an internal chromosome 17 centromere control probe). In other words, the HER2-positive cancer may, inter alia, relate to a HER2 gene copy number greater than 4. The amplification level of the HER2 gene may easily be identified by in situ hybridization (ISH) like fluorescent in situ hybridization (FISH), chromogenic in situ hybridization (CISH) and silver in situ hybridization (SISH). These methods are known to the skilled artisan. The principles of these methods can be deduced from standard text books. Commercial kits for the determination of the HER2 gene amplification status by in situ hybridization are available.

[0073] The HER2-positive cancer may be breast cancer or gastric cancer. Further, the HER2-positive cancer may be ovarian cancer, lung cancer, colorectal cancer, kidney cancer, bone cancer, bone marrow cancer, bladder cancer, skin cancer, prostate cancer, esophagus cancer, salivary gland cancer, pancreas cancer, liver cancer, head and neck cancer, CNS (especially brain) cancer, cervix cancer, cartilage cancer, colon cancer, genitourinary cancer, gastrointestinal tract cancer, pancreas cancer, synovium cancer, testis cancer, thymus cancer, thyroid cancer and uterine cancer. In one embodiment the breast cancer is early-stage breast cancer, as also assessed in the appended example.

[0074] The sample to be assessed in accordance with the herein provided methods for identification a non-responder to a HER2 inhibitor may comprise non-diseased cells and/or diseased cells, i.e. non-cancerous cells and/or cancerous cells however the content of cancerous cells among non cancerous cells should be higher than 50%. The sample may also (or even solely) comprise cancer/tumor cell(s), such as breast cancer/tumor cell(s). The term “sample” shall generally mean any biological sample obtained from a patient's tumor. The sample may be a tissue resection or a tissue biopsy. The sample may also be a metastatic lesion or a section of a metastatic lesion or a blood sample known or suspected to comprise circulating tumor cells. In accordance with the above, the biological sample may comprise cancer cells and to a certain extent i.e. less than 50% non-cancer cells (other cells). The skilled pathologist is able to differentiate cancer cells from normal tissue cells. Methods for obtaining tissue biopsies, tissue resections and body fluids and the like from mammals, such as humans, are well known in the art.

[0075] As mentioned, the sample is obtained from a patient with HER2-positive cancer as defined above. For example, the sample may be obtained from a tumorous tissue, (a) tumor(s) and, accordingly, is (a) tumor cell(s) or (a) tumor tissue(s) suspected of being HER2-positive tumour, like a breast tumor and the like. A person skilled in the art is in the position to identify such tumors and/or individuals/patients suffering from corresponding cancer using standard techniques known in the art and methods disclosed herein. Generally, said tumor cell or cancer cell may be obtained from any biological source/organism, particularly any biological source/organism, suffering from the above-mentioned cancer. In context of this invention particular useful cells are, preferably, human cells. These cells can be obtained from e.g. biopsies or from biological samples. The tumor/cancer/tumor cell/cancer cell is a solid tumor/cancer/tumor cell/cancer cell. In accordance with the above, the cancer/tumor cell may be a breast cancer/tumor cell or said sample comprises a cancer/tumor cell, such as a breast cancer/tumor cell. In line with the above, said tumor/cancer may be a breast tumor/cancer.

[0076] The method for identifying a non-responder to a HER2-inhibitor provided herein may further comprise obtaining a sample of tissue from a patient with HER2-positive cancer prior to said step of identifying. The tissue may be cancerous tissue. The method may further comprise adjusting the treatment of the patient in response to the presence of said one or more mutations in exon 9.

[0077] The identification of non-responders allows for the treatment of patients that do not have the mutations in exon 9 of PIK3CA, as these patients respond well to treatment with HER2 inhibitor(s), such as Pertuzumab. Accordingly, the present invention relates in one embodiment to an inhibitor of HER2 for use in treating a patient with HER2-positive cancer, whereby the cancer has been found to be PIK3CA mutation-negative in Exon 9 of PIK3CA. Also the use of an inhibitor of HER2 for the preparation of a pharmaceutical composition for the treatment of a HER2-positive cancer patient is envisaged, whereby the cancer has been found to be PIK3CA mutation-negative.

[0078] Further, the present invention relates to the use of a HER2 inhibitor to treat a HER2-positive cancer patient by administering the HER2 dimerization inhibitor in an amount effective to treat the cancer, provided the cancer has been found to be PIK3CA mutation-negative. Accordingly, a method for the treatment of a HER2-positive cancer patient is provided which comprises administering the HER2 dimerization inhibitor in an amount effective to treat the cancer, provided the cancer has been found to be PIK3CA mutation-negative. The term “PIK3CA mutation-negative” as used herein means that the mutations are not present (absent). As mentioned above, the PIK3CA mutation comprises or consists of preferably one or more mutations in exon 9 of Phosphoatidylinositol-3 kinase (PIK3CA) as defined herein above. Preferably, the patient is a human.

[0079] In one embodiment of the present invention, the HER2 inhibitor is to be administered as a single anti-tumor agent. In a further embodiment, the inhibitor may be administered in form of a combination therapy, such as chemotherapy, an anti-hormonal therapy and/or another HER2 targeted agent/another HER2 targeted therapy in addition.

[0080] The chemotherapy may be docetaxel, anthracycline/taxane chemotherapy, therapy with an anti-metabolite agents, therapy with an anti-hormonal compound, therapy with an anti-estrogen, therapy with a tyrosine kinase inhibitor, therapy with a raf inhibitor, therapy with a ras inhibitor, therapy with a dual tyrosine kinase inhibitor, therapy with taxol, therapy with taxane, therapy with doxorubicin, therapy with adjuvant (anti-) hormone drugs and/or therapy with cisplatin and the like. In accordance with the present invention, the HER2 inhibitor may be administered by any one of a parenteral route, oral route, intravenous route, subcutaneous route, intranasal route or transdermal route. Further, the HER2 inhibitor may be employed in a neoadjuvant or adjuvant setting. Accordingly, said HER2 inhibitor may be administered to a patient in need of such a treatment and having the herein defined biomarker status before, during or after a surgical intervention/resection of the cancerous tissue. Therefore, the present invention is useful in neoadjuvant therapy, i.e. the treatment with the herein defined HER2 inhibitor (like Pertuzumab or Trastuzumab) given to the herein defined cancer patient group prior to surgery, as well as in adjuvant therapy. Again, the patient group of the present invention to be treated by the means and methods provided herein (in particular with Pertuzumab) are cancer patients without one or more mutations in exon 9 of PIK3CA. The attending physician may modify, change or amend the administration schemes for the HER2 inhibitor in accordance with his/her professional experience.

[0081] In one embodiment, the HER2 inhibitor is a HER dimerization/signaling inhibitor or an inhibitor of HER2 shedding. The HER dimerization inhibitor may be a HER2 dimerization inhibitor. HER dimerization inhibitor inhibits HER heterodimerization or HER homodimerization. The HER dimerization inhibitor may be an anti-HER antibody.

[0082] The term “antibody” herein is used in the broadest sense and specifically covers intact monoclonal antibodies, polyclonal antibodies, multispecific antibodies (e.g., bispecific antibodies) formed from at least two intact antibodies, and antibody fragments, so long as they exhibit the desired biological activity. Also human and humanized as well as CDR-grafted antibodies are comprised.

[0083] The HER antibody may bind to a HER receptor selected from the group consisting of EGFR, HER2 and HER3. Preferably, the antibody binds to HER2. In one embodiment, the anti HER2 antibody may bind to domain II of HER2 extracellular domain. In another embodiment, the antibody may bind to a junction between domains I, II and III of HER2 extracellular domain. Most preferably, the anti HER2 antibody is Pertuzumab.

[0084] For the purposes herein, “Pertuzumab” and “rhuMAb 2C4”, which are used interchangeably, refer to an antibody comprising the variable light and variable heavy domains (amino acid sequences thereof shown in SEQ ID Nos. 5 and 6, respectively, as depicted in FIG. 2). The variable light and variable heavy domains of variant 574/Pertuzumab are also shown in FIG. 2 (amino acid sequences thereof shown in SEQ ID Nos. 7 and 8, respectively, as depicted in FIG. 2). Where Pertuzumab is an intact antibody, it preferably comprises an IgG1 antibody; in one embodiment comprising the light chain amino acid sequence in it preferably comprises the light chain and heavy chain amino acid sequences in SEQ ID Nos. 11 and 12, respectively, as shown in FIGS. 3A/3B and 5A/5B (FIG. 5A/5B show the light chain and heavy chain amino acid sequences of a variant Pertuzumab, SEQ ID NO:s 15 and 16, respectively). The heavy chain amino acid sequences of Pertuzumab as shown in SEQ ID NO: 12 (FIG. 3B) may optionally comprise an additional amino acid “K” at position 449 at the C-terminus. The antibody is optionally produced by recombinant Chinese Hamster Ovary (CHO) cells. The terms “Pertuzumab” and “rhuMAb 2C4” herein cover biosimilar versions of the drug with the United States Adopted Name (USAN) or International Nonproprietary Name (INN): Pertuzumab. Again, corresponding sequences are shown in FIGS. 2 to 5.

[0085] In a further embodiment, the inhibitor of HER shedding is a HER2 shedding inhibitor. The inhibitor of HER shedding may inhibit HER heterodimerization or HER homodimerization. Said inhibitor of HER shedding may be an anti-HER antibody. The anti-HER antibody may bind to a HER receptor selected from the group consisting of EGFR, HER2 and HER3. Preferably, the antibody binds to HER2. In one embodiment, the HER2 antibody binds to sub-domain IV of the HER2 extracellular domain. Preferably, the HER2 antibody is Herceptin™/Trastuzumab.

[0086] For the purposes herein, “Trastuzumab” and “rhuMAb4D5-8”, which are used interchangeably, refer to an antibody comprising the variable light domains and variable heavy domains (amino acid sequences thereof are shown in FIG. 4 in SEQ ID NO: 13 and 14, respectively; the domain is indicated by arrows). Where Trastuzumab is an intact antibody, it preferably comprises an IgG1 antibody; in one embodiment comprising the light chain amino acid sequence of SEQ ID NO: 13 and the heavy chain amino acid sequence of SEQ ID NO: 14 as shown in FIG. 4. The antibody is optionally produced by Chinese Hamster Ovary (CHO) cells. The terms “Trastuzumab” and “rhuMAb4D5-8” herein cover biosimilar versions of the drug with the United States Adopted Name (USAN) or International Nonproprietary Name (INN): Trastuzumab.

[0087] The HER2 positive cancer to be treated may be breast cancer, such early stage breast cancer. The term “early-stage breast cancer” as used herein refers to breast cancer that has not spread beyond the breast or the axilliary lymph nodes. Such cancer is generally treated with neoadjuvant or adjuvant therapy. “Neoadjuvant therapy” refers to systemic therapy given prior to surgery. “Adjuvant therapy” refers to systemic therapy given after surgery. Also other HER2 positive cancer types like gastric cancer can be treated in accordance with the present invention. In one embodiment, the treatment is neoadjuvant or adjuvant therapy of the early-stage breast cancer.

[0088] The pharmaceutical composition to be employed in the medical uses of the present invention, will be formulated and dosed in a fashion consistent with good medical practice, taking into account the clinical condition of the individual patient, the site of delivery of the pharmaceutical composition, the method of administration, the scheduling of administration, and other factors known to practitioners. The “effective amount” of the pharmaceutical composition for purposes herein is thus determined by such considerations.

[0089] The skilled person knows that the effective amount of pharmaceutical composition administered to an individual will, inter alia, depend on the nature of the compound. For example, if said compound is a (poly)peptide or protein the total pharmaceutically effective amount of pharmaceutical composition administered parenterally per dose will be in the range of about 1 μg protein/kg/day to 10 mg protein/kg/day of patient body weight, although, as noted above, this will be subject to therapeutic discretion. More preferably, this dose is at least 0.01 mg protein/kg/day, and most preferably for humans between about 0.01 and 1 mg protein/kg/day.

[0090] The following administration may be employed in respect of Pertuzumab:

[0091] A dosing regimen of pertuzumab administered every 3 weeks to patients in Phase II studies (TOC2689g, BO16934) using a fixed 840 mg loading dose (equivalent to 12 mg/kg for a 70 kg patient) for treatment cycle 1 followed by a fixed 420 mg “maintenance” dose (equivalent to 6 mg/kg) for subsequent treatment cycles resulted in steady-state serum trough concentrations of approximately 60 μg/mL by the second treatment cycle. A dose based on body-surface area or weight was not superior to a fixed dose, supporting the continued use of a fixed dose of pertuzumab in female patients with locally advanced, inflammatory or early stage HER2-positive breast cancer, metastatic breast cancer and ovarian cancer.

[0092] If given continuously, the pharmaceutical composition is typically administered at a dose rate of about 1 μg/kg/hour to about 50 μg/kg/hour, either by 1-4 injections per day or by continuous subcutaneous infusions, for example, using a mini-pump. An intravenous bag solution may also be employed. The length of treatment needed to observe changes and the interval following treatment for responses to occur appears to vary depending on the desired effect. The particular amounts may be determined by conventional tests which are well known to the person skilled in the art. Pharmaceutical compositions of the invention may be administered orally, rectally, parenterally, intracisternally, intravaginally, intraperitoneally, topically (as by powders, ointments, drops or transdermal patch), bucally, or as an oral or nasal spray.

[0093] Pharmaceutical compositions of the invention may comprise a pharmaceutically acceptable carrier. By “pharmaceutically acceptable carrier” is meant a non-toxic solid, semisolid or liquid filler, diluent, encapsulating material or formulation auxiliary of any type. The term “parenteral” as used herein refers to modes of administration which include intravenous, intramuscular, intraperitoneal, intrasternal, subcutaneous and intraarticular injection and infusion.

[0094] The pharmaceutical composition is also suitably administered by sustained release systems. Suitable examples of sustained-release compositions include semi-permeable polymer matrices in the form of shaped articles, e.g., films, or microcapsules. Sustained-release matrices include polylactides (U.S. Pat. No. 3,773,919, EP 58,481), copolymers of L-glutamic acid and gamma-ethyl-L-glutamate (Sidman, U. et al., Biopolymers 22:547-556 (1983)), poly(2-hydroxyethyl methacrylate) (R. Langer et al., J. Biomed. Mater. Res. 15:167-277 (1981), and R. Langer, Chem. Tech. 12:98-105 (1982)), ethylene vinyl acetate (R. Langer et al., Id.) or poly-D-(−)-3-hydroxybutyric acid (EP 133,988). Sustained release pharmaceutical composition also include liposomally entrapped compound. Liposomes containing the pharmaceutical composition are prepared by methods known per se: DE 3,218,121; Epstein et al., Proc. Natl. Acad. Sci. (USA) 82:3688-3692 (1985); Hwang et al., Proc. Natl. Acad. Sci. (USA) 77:4030-4034 (1980); EP 52,322; EP 36,676; EP 88,046; EP 143,949; EP 142,641; Japanese Pat. Appl. 83-118008; U.S. Pat. Nos. 4,485,045 and 4,544,545; and EP 102,324. Ordinarily, the liposomes are of the small (about 200-800 Angstroms) unilamellar type in which the lipid content is greater than about 30 mol. percent cholesterol, the selected proportion being adjusted for the optimal therapy.

[0095] For parenteral administration, the pharmaceutical composition is formulated generally by mixing it at the desired degree of purity, in a unit dosage injectable form (solution, suspension, or emulsion), with a pharmaceutically acceptable carrier, i.e., one that is non-toxic to recipients at the dosages and concentrations employed and is compatible with other ingredients of the formulation.

[0096] Generally, the formulations are prepared by contacting the components of the pharmaceutical composition uniformly and intimately with liquid carriers or finely divided solid carriers or both. Then, if necessary, the product is shaped into the desired formulation. The carrier may be a parenteral carrier, such as a solution that is isotonic with the blood of the recipient. Examples of such carrier vehicles include water, saline, Ringer's solution, and dextrose solution. Non aqueous vehicles such as fixed oils and ethyl oleate are also useful herein, as well as liposomes. The carrier suitably contains minor amounts of additives such as substances that enhance isotonicity and chemical stability. Such materials are non-toxic to recipients at the dosages and concentrations employed, and include buffers such as phosphate, citrate, succinate, acetic acid, and other organic acids or their salts; antioxidants such as ascorbic acid; low molecular weight (less than about ten residues) (poly)peptides, e.g., polyarginine or tripeptides; proteins, such as serum albumin, gelatin, or immunoglobulins; hydrophilic polymers such as polyvinylpyrrolidone; amino acids, such as glycine, glutamic acid, aspartic acid, or arginine; monosaccharides, disaccharides, and other carbohydrates including cellulose or its derivatives, glucose, manose, or dextrins; chelating agents such as EDTA; sugar alcohols such as mannitol or sorbitol; counterions such as sodium; and/or nonionic surfactants such as polysorbates, poloxamers, or PEG.

[0097] The components of the pharmaceutical composition to be used for therapeutic administration must be sterile. Sterility is readily accomplished by filtration through sterile filtration membranes (e.g., 0.2 micron membranes). Therapeutic components of the pharmaceutical composition generally are placed into a container having a sterile access port, for example, an intravenous solution bag or vial having a stopper pierceable by a hypodermic injection needle.

[0098] The components of the pharmaceutical composition ordinarily will be stored in unit or multi-dose containers, for example, sealed ampoules or vials, as an aqueous solution or as a lyophilized formulation for reconstitution. As an example of a lyophilized formulation, 10-ml vials are filled with 5 ml of sterile-filtered 1% (w/v) aqueous solution, and the resulting mixture is lyophilized. The infusion solution is prepared by reconstituting the lyophilized compound(s) using bacteriostatic Water-for-Injection.

[0099] Another embodiment of the present invention relates to the use of a nucleic acid or antibody capable of detecting a mutation in exon 9 of PIK3CA for identifying a non-responder to a HER2-inhibitor in accordance with the herein provided methods. The oligonucleotide(s) may be about 15 to 100 nucleotides in length.

[0100] Accordingly, the present invention relates in one embodiment to a forward primer having the sequence 5′-UAAAAUUUAUUGAGAAUGUAUUUGCTTTTTC-3′ (SEQ ID NO: 25). This forward primer can be used in amplification of exon 9 or a part thereof encoding the mutant triplet which encodes position 542 and/or 545 of the herein described mutant exon 9 of PIKC3A. In a further embodiment, the present invention relates to a reverse primer having the sequence 5′-TCCATTTTAGCACTTACCTGTGAC-3′ (SEQ ID NO: 26). This reverse primer can also be used in amplification of exon 9 or a part thereof encoding the mutant triplet which encodes position 542 and/or 545 of the herein described mutant exon 9 of PIKC3A. The present invention provides a primer pair of the forward primer having the sequence 5′-UAAAAUUUAUUGAGAAUGUAUUUGCTTTTTC-3′ (SEQ ID NO: 25) and the reverse primer having the sequence 5′-TCCATTTTAGCACTTACCTGTGAC-3′ (SEQ ID NO: 26).

[0101] In a further embodiment, the present invention relates to probe(s)/probe sequence(s) for evaluating/determining the presence of one or more mutations in exon 9 of PIK3CA. In one embodiment, the present invention relates to a probe having the sequence 5′-FTTTCAQAGAGAGGAUEUEGUGUAGAAAUUGEP-3′ (“542 WT Probe”) (SEQ ID NO: 27). In one embodiment, the present invention relates to a probe having the sequence 5′-LATTTTQGAGAGAGGAUEUEGUGUAGAAAUUGEUUP-3′ (542K Mutation Probe) (SEQ ID NO: 28). In one embodiment, the present invention relates to a probe having the sequence 5′-OCTGCTCAGTQAUUUIAGAGAGAGGATCTCGTGTP-3′ (545 WT Probe) (SEQ ID NO: 29). In one embodiment, the present invention relates to a probe having the sequence 5′-JAATCACTAAGQAGGAGAAAGAUUUUEUAUGGAGUEP-3′ (545K Mutation Probe) (SEQ ID NO: 30). In one embodiment, the present invention relates to a probe having the sequence 5′-FCTGCGCQGGAGAAAGAUUUUEUAUGGAGUEAP-3′ (545A Mutation Probe) (SEQ ID NO: 31). In one embodiment, the present invention relates to a probe having the sequence 5′-LCCTGCCCQGTGAUUUIAGAGAGAGGATCTCGP-3′ (545G Mutation Probe) (SEQ ID NO: 32). In this context, the following abbreviations used: F=FAM Reporter Dye, J=JA270 Reporter Dye, O=CY5.5 Reporter Dye, L=HEX Reporter Dye, U=5-propynyl dU, E=5-methyl dC, I=deoxyinosine, Z=7-deaza dG, Q=BHQ2 Quencher Dye, P=3′ Phosphate

[0102] A person skilled in the art is, based on his general knowledge and the teaching provided herein, in the position to identify and/or prepare further oligo-polynucleotide(s) for use in the present methods. In particular these oligo- or polynucleotides may be used as probe(s) in the detection methods described herein. A skilled person will know, for example, computer programs which may be useful for the identification of corresponding probes to be used herein. For example, the PIK3CA coding sequence (SEQ ID NO: 1) may be used in this context. Exemplary nucleic acid sequences are available on corresponding databases, such as the NCBI database available online at ncbi.nlm.nih.gov/sites/entrez

[0103] The present invention also relates to a kit useful for carrying out the herein provided methods, the kit comprising a nucleic acid or an antibody capable of detecting a mutation in exon 9 of PIK3CA. Also envisaged herein is the use of the herein described kit for carrying out the herein provided methods.

[0104] For example, said kit may comprise (a) compound(s) required for specifically determining the one or more mutations in exon 9 of PIK3CA. Moreover, the present invention also relates to the use of (a) compound(s) required for specifically determining the presence of one or more mutations in exon 9 of PIK3CA for the preparation of a kit for carrying out the methods or uses of this invention.

[0105] On the basis of the teaching of this invention, the skilled person knows which compound(s) is (are) required for specifically determining the presence of one or more mutations in exon 9 of PIK3CA. Particularly, such compound(s) may be (a) (nucleotide) probe(s), (a) primer(s) (pair(s)), (an) antibody(ies) and/or (an) aptamer(s) specific to the mutation described herein. The kit (to be prepared in context) of this invention may be a diagnostic kit.

[0106] The kit (to be prepared in context) of this invention or the methods and uses of the invention may further comprise or be provided with (an) instruction manual(s). For example, said instruction manual(s) may guide the skilled person (how) to determine one or more mutations in exon 9 of PIK3CA i.e. (how) to diagnose non-responsiveness to a HER2 inhibitor. Particularly, said instruction manual(s) may comprise guidance to use or apply the herein provided methods or uses.

[0107] The kit (to be prepared in context) of this invention may further comprise substances/chemicals and/or equipment suitable/required for carrying out the methods and uses of this invention. For example, such substances/chemicals and/or equipment are solvents, diluents and/or buffers for stabilizing and/or storing (a) compound(s) required for specifically determining the presence of a mutation in exon 9 of PIK3CA.

[0108] The present invention relates to a method of detecting mutations in the human PI3KCA nucleic acid in a sample comprising:

[0109] (a) contacting the nucleic acid in the sample with at least one mutation-specific oligonucleotide from Table 2;

[0110] (b) incubating the sample under conditions allowing hybridization of the oligonucleotide to the target sequence within the PI3KCA nucleic acid;

[0111] (c) detecting the hybridization thereby detecting the presence of the mutation in the PI3KCA nucleic acid.

[0112]

TABLE 2
Probe Sequences for the
PIK3CA Mutation Detection Test
Probe	Sequence 5′ to 3′
542 WT Probe	FTTTCAQAGAGAGGAUEUEGUGUAGAAA
	UUGEP (SEQ ID NO: 27)
542 542K	LATTTTQGAGAGAGGAUEUEGUGUAGAA
Mutation Probe	AUUGEUUP (SEQ ID NO: 28)
545 WT Probe	OCTGCTCAGTQAUUUIAGAGAGAGGATC
	TCGTGTP (SEQ ID NO: 29)
545 545K	JAATCACTAAGQAGGAGAAAGAUUUUEU
Mutation Probe	AUGGAGUEP (SEQ ID NO: 30)
545 545A	FCTGCGCQGGAGAAAGAUUUUEUAUGGA
Mutation Probe	GUEAP (SEQ ID NO: 31)
545 545G	LCCTGCCCQGTGAUUUIAGAGAGAGGAT
Mutation Probe	CTCGP (SEQ ID NO: 32)
Key:
F = FAM Reporter Dye,
J = JA270 Reporter Dye,
O = CY5.5 Reporter Dye,
L = HEX Reporter Dye,
U = 5-propynyl dU,
E = 5-methyl dC,,
I = deoxyinosine,
Z = 7-deaza dG,
Q = BHQ2 Quencher Dye,
P = 3′ Phosphate

[0113] The present invention relates to a method of detecting mutations in the human PI3KCA nucleic acid in a sample comprising:

[0114] (a) contacting the nucleic acid in the sample with one or more of the following mutation-specific oligonucleotides:

[0115]

	(542 542K Mutation Probe)
	(SEQ ID NO: 28)
	LATTTTQGAGAGAGGAUEUEGUGUAGAAAUUGEUUP;
	(545 545K Mutation Probe)
	(SEQ ID NO: 30)
	JAATCACTAAGQAGGAGAAAGAUUUUEUAUGGAGUEP;
	(545 545A Mutation Probe)
	(SEQ ID NO: 31)
	FCTGCGCQGGAGAAAGAUUUUEUAUGGAGUEAP;
	and/or
	(545 545G Mutation Probe)
	(SEQ ID NO: 32)
	LCCTGCCCQGTGAUUUIAGAGAGAGGATCTCGP;

[0116] (b) incubating the sample under conditions allowing hybridization of the one or more oligonucleotide to the target sequence within the PI3KCA nucleic acid;

[0117] (c) detecting the hybridization thereby detecting the presence of the mutation in the PI3KCA nucleic acid.

[0118] The method may further comprise, prior to detection in step (c), contacting the nucleic acid in the sample with at least one oligonucleotide from Table 1 and generating an amplification product containing the target sequence within the PI3KCA nucleic acid.

[0119]

TABLE 1
Primer Sequences for the
PIK3CA Mutation Detection Test
	Primer	Sequence 5′ to 3′
	542/545	UAAAAUUUAUUGAGAAUGUAUUUG
	Forward primer	CTTTTTC (SEQ ID NO: 25)
	PIK3CA-9F13
	542/545	TCCATTTTAGCACTTACCTGTGAC
	Reverse primer	(SEQ ID NO: 26)
	PIK3CA-9R01
	Key:
	U = 5-propynyl dU

[0120] The present invention relates to a method of detecting mutations in the human PI3KCA nucleic acid in a sample comprising:

[0121] (a) contacting the nucleic acid in the sample with at least one mutation-specific oligonucleotide from Table 2;

[0122] (b) (i) incubating the sample under conditions allowing hybridization of the oligonucleotide to the target sequence within the PI3KCA nucleic acid;

• • [0123] (ii) contacting the nucleic acid in the sample with at least one oligonucleotide from Table 1
  • [0124] (iii) generating an amplification product containing the target sequence within the PI3KCA nucleic acid;

[0125] (c) detecting the hybridization thereby detecting the presence of the mutation in the PI3KCA nucleic acid.

[0126] In accordance with the above, the present invention provides a method of detecting mutations in the human PI3KCA nucleic acid in a sample comprising:

[0127] (a) contacting the nucleic acid in the sample with one or more of the following mutation-specific oligonucleotides:

[0128]

	(542 542K Mutation Probe)
	(SEQ ID NO: 28)
	LATTTTQGAGAGAGGAUEUEGUGUAGAAAUUGEUUP;
	(545 545K Mutation Probe)
	(SEQ ID NO: 30)
	JAATCACTAAGQAGGAGAAAGAUUUUEUAUGGAGUEP;
	(545 545A Mutation Probe)
	(SEQ ID NO: 31)
	FCTGCGCQGGAGAAAGAUUUUEUAUGGAGUEAP;
	and/or
	(545 545G Mutation Probe)
	(SEQ ID NO: 32)
	LCCTGCCCQGTGAUUUIAGAGAGAGGATCTCGP;

[0129] (b) (i) incubating the sample under conditions allowing hybridization of the oligonucleotide to the target sequence within the PI3KCA nucleic acid;

• • [0130] (ii) contacting the nucleic acid in the sample with one or both of the following oligonucleotides:

[0131]

	(542/545 Forward primer PIK3CA-9F13)
	(SEQ ID NO: 25)
	UAAAAUUUAUUGAGAAUGUAUUUGCTTTTTC
	and/or
	(542/545 Reverse primer PIK3CA-9R01)
	(SEQ ID NO: 26)
	TCCATTTTAGCACTTACCTGTGAC;

• • [0132] (iii) generating an amplification product containing the target sequence within the PI3KCA nucleic acid;

[0133] (c) detecting the hybridization thereby detecting the presence of the mutation in the PI3KCA nucleic acid.

[0134] The present invention provides a method of determining whether a patient having a malignant tumor is likely to respond to a HER2-inhibitor, comprising:

[0135] (a) contacting the nucleic acid in the sample from the patient with the oligonucleotide from Table 2;

[0136] (b) incubating the sample under conditions allowing hybridization of the oligonucleotide to the target sequence within the PI3KCA nucleic acid;

[0137] (c) detecting the hybridization thereby detecting the presence of the mutation in the PI3KCA nucleic acid, wherein the presence of the mutation indicates that the patient is likely to respond to the HER2 inhibitor.

[0138]

TABLE 2
Probe Sequences for the
PIK3CA Mutation Detection Test
Probe	Sequence 5′ to 3′
542 WT Probe	FTTTCAQAGAGAGGAUEUEGUGUAGAAA
	UUGEP (SEQ ID NO: 27)
542 542K	LATTTTQGAGAGAGGAUEUEGUGUAGAA
Mutation Probe	AUUGEUUP (SEQ ID NO: 28)
545 WT Probe	OCTGCTCAGTQAUUUIAGAGAGAGGATC
	TCGTGTP (SEQ ID NO: 29)
545 545K	JAATCACTAAGQAGGAGAAAGAUUUUEU
Mutation Probe	AUGGAGUEP (SEQ ID NO: 30)
545 545A	FCTGCGCQGGAGAAAGAUUUUEUAUGGA
Mutation Probe	GUEAP (SEQ ID NO: 31)
545 545G	LCCTGCCCQGTGAUUUIAGAGAGAGGAT
Mutation Probe	CTCGP (SEQ ID NO: 32)
Key:
F = FAM Reporter Dye,
J = JA270 Reporter Dye,
O = CY5.5 Reporter Dye,
L = HEX Reporter Dye,
U = 5-propynyl dU,
E = 5-methyl dC,,
I = deoxyinosine,
Z = 7-deaza dG,
Q = BHQ2 Quencher Dye,
P = 3′ Phosphate

[0139] The method may further comprise, prior to detection in step (c), contacting the nucleic acid in the sample with at least one oligonucleotide from Table 1 and generating an amplification product containing the target sequence within the PI3KCA nucleic acid.

[0140]

TABLE 1
Primer Sequences for the
PIK3CA Mutation Detection Test
	Primer	Sequence 5′ to 3′
	542/545	UAAAAUUUAUUGAGAAUGUAUUU
	Forward primer	GCTTTTTC (SEQ ID NO: 25)
	PIK3CA-9F13
	542/545	TCCATTTTAGCACTTACCTGTGAC
	Reverse primer	(SEQ ID NO: 26)
	PIK3CA-9R01
	Key:
	U = 5-propynyl dU

[0141] The present invention provides a method of determining whether a patient having a malignant tumor is less likely to respond to a HER2-inhibitor, comprising:

[0142] (a) contacting the nucleic acid in the sample from the patient with one or more of the following mutation-specific oligonucleotides:

[0143]

	(542 542K Mutation Probe)
	(SEQ ID NO: 28)
	LATTTTQGAGAGAGGAUEUEGUGUAGAAAUUGEUUP;
	(545 545K Mutation Probe)
	(SEQ ID NO: 30)
	JAATCACTAAGQAGGAGAAAGAUUUUEUAUGGAGUEP;
	(545 545A Mutation Probe)
	(SEQ ID NO: 31)
	FCTGCGCQGGAGAAAGAUUUUEUAUGGAGUEAP;
	and/or
	(545 545G Mutation Probe)
	(SEQ ID NO: 32)
	LCCTGCCCQGTGAUUUIAGAGAGAGGATCTCGP;

[0144] (b) incubating the sample under conditions allowing hybridization of the oligonucleotide to the target sequence within the PI3KCA nucleic acid;

[0145] (c) detecting the hybridization thereby detecting the presence of the mutation in the PI3KCA nucleic acid, wherein the presence of the mutation indicates that the patient is less likely to respond to the HER2 inhibitor.

[0146] The present invention relates to a method of determining whether a patient having a malignant tumor is less likely to respond to a HER2-inhibitor, comprising:

[0147] (a) contacting the nucleic acid in the sample from the patient with one or more of the following mutation-specific oligonucleotides:

[0148]

	(542 542K Mutation Probe)
	(SEQ ID NO: 28)
	LATTTTQGAGAGAGGAUEUEGUGUAGAAAUUGEUUP;
	(545 545K Mutation Probe)
	(SEQ ID NO: 30)
	JAATCACTAAGQAGGAGAAAGAUUUUEUAUGGAGUEP;
	(545 545A Mutation Probe)
	(SEQ ID NO: 31)
	FCTGCGCQGGAGAAAGAUUUUEUAUGGAGUEAP;
	and/or
	(545 545G Mutation Probe)
	(SEQ ID NO: 32)
	LCCTGCCCQGTGAUUUIAGAGAGAGGATCTCGP;

[0149] (b) (i) incubating the sample under conditions allowing hybridization of the oligonucleotide to the target sequence within the PI3KCA nucleic acid;

• • [0150] (ii) contacting the nucleic acid in the sample with one or both of the following oligonucleotides:

[0151]

	(542/545 Forward primer PIK3CA-9F13)
	(SEQ ID NO: 25)
	UAAAAUUUAUUGAGAAUGUAUUUGCTTTTTC
	and/or
	(542/545 Reverse primer PIK3CA-9R01)
	(SEQ ID NO: 26)
	TCCATTTTAGCACTTACCTGTGAC;

• • [0152] (iii) generating an amplification product containing the target sequence within the PI3KCA nucleic acid;

[0153] (c) detecting the hybridization thereby detecting the presence of the mutation in the PI3KCA nucleic acid, wherein the presence of the mutation indicates that the patient is less likely to respond to the HER2 inhibitor.

[0154] The present invention provides a method for identifying a non-responder to a HER2-inhibitor, said method comprising

[0155] a) detecting the presence of one or more mutations in exon 9 of the catalytic subunit of Phosphoinositol-3 kinase (PIK3CA or p110α) nucleic acid in a sample from an individual,

[0156] (b)) identifying the patient as less likely to respond to a HER2 inhibitor if the presence of one or more mutations in exon 9 of the catalytic subunit of Phosphoinositol-3 kinase (PIK3CA or p110α) nucleic acid is detected.

[0157] The present invention provides a method for identifying a non-responder to a HER2-inhibitor, said method comprising detecting the presence of one or more mutations in exon 9 of the catalytic subunit of Phosphoinositol-3 kinase (PIK3CA or p110α) nucleic acid by

[0158] (a) contacting the nucleic acid in the sample from a patient with HER2-positive cancer with a oligonucleotide comprising a sequence from Table 2;

[0159] (b) incubating the sample under conditions allowing hybridization of the oligonucleotide to the target sequence within the PIK3CA nucleic acid;

[0160] (c) detecting hybridization

[0161] (d) identifying the patient as less likely to respond to a HER2 inhibitor if the presence of one or more mutations in exon 9 of the catalytic subunit of Phosphoinositol-3 kinase (PIK3CA or p110α) nucleic acid is detected.

[0162]

TABLE 2
Probe Sequences for the
PIK3CA Mutation Detection Test
Probe	Sequence 5′ to 3′
542 WT Probe	FTTTCAQAGAGAGGAUEUEGUGUAGAAA
	UUGEP (SEQ ID NO: 27)
542 542K	LATTTTQGAGAGAGGAUEUEGUGUAGAA
Mutation Probe	AUUGEUUP (SEQ ID NO: 28)
545 WT Probe	OCTGCTCAGTQAUUUIAGAGAGAGGATC
	TCGTGTP (SEQ ID NO: 29)
545 545K	JAATCACTAAGQAGGAGAAAGAUUUUEU
Mutation Probe	AUGGAGUEP (SEQ ID NO: 30)
545 545A	FCTGCGCQGGAGAAAGAUUUUEUAUGGA
Mutation Probe	GUEAP (SEQ ID NO: 31)
545 545G	LCCTGCCCQGTGAUUUIAGAGAGAGGAT
Mutation Probe	CTCGP (SEQ ID NO: 32)
Key:
F = FAM Reporter Dye,
J = JA270 Reporter Dye,
O = CY5.5 Reporter Dye,
L = HEX Reporter Dye,
U = 5-propynyl dU,
E = 5-methyl dC,,
I = deoxyinosine,
Z = 7-deaza dG,
Q = BHQ2 Quencher Dye,
P = 3′ Phosphate

[0163] The term “non-responder” as used herein can refer to a “patient who is less likely to respond” “Less likely to respond” as used herein refers to a decreased likeliness that a pathological complete response (pcR) will occur in a patient treated with a HER2 inhibitor.

[0164] The present invention relates to a method for identifying a non-responder to a HER2-inhibitor, said method comprising detecting the presence of one or more mutations in exon 9 of the catalytic subunit of Phosphoinositol-3 kinase (PIK3CA or p110α) nucleic acid by

[0165] (a) contacting the nucleic acid in the sample from a patient with HER2-positive cancer with one or more of the following mutation-specific oligonucleotides:

[0166]

	(542 542K Mutation Probe)
	(SEQ ID NO: 28)
	LATTTTQGAGAGAGGAUEUEGUGUAGAAAUUGEUUP;
	(545 545K Mutation Probe)
	(SEQ ID NO: 30)
	JAATCACTAAGQAGGAGAAAGAUUUUEUAUGGAGUEP;
	(545 545A Mutation Probe)
	(SEQ ID NO: 31)
	FCTGCGCQGGAGAAAGAUUUUEUAUGGAGUEAP;
	and/or
	(545 545G Mutation Probe)
	(SEQ ID NO: 32)
	LCCTGCCCQGTGAUUUIAGAGAGAGGATCTCGP;

[0167] (b) incubating the sample under conditions allowing hybridization of the oligonucleotide to the target sequence within the PIK3CA nucleic acid;

[0168] (c) detecting hybridization

[0169] (d) identifying the patient as less likely to respond to a HER2 inhibitor if the presence of one or more mutations in exon 9 of the catalytic subunit of Phosphoinositol-3 kinase (PIK3CA or p110α) nucleic acid is detected.

[0170] The method can further comprise, prior to detection in step (c), contacting the nucleic acid in the sample with at least one oligonucleotide from Table 1 and generating an amplification product containing the target sequence within the PI3KCA nucleic acid.

[0171]

TABLE 1
Primer Sequences for the PIK3CA
Mutation Detection Test
Primer	Sequence 5′ to 3′
542/545 Forward primer	UAAAAUUUAUUGAGAAUGUAUUUGC
PIK3CA-9F13	TTTTTC (SEQ ID NO: 25)
542/545 Reverse primer	TCCATTTTAGCACTTACCTGTGAC
PIK3CA-9R01	(SEQ ID NO: 26)
Key:
U = 5-propynyl dU

[0172] The present invention relates to a method for identifying a non-responder to a HER2-inhibitor, said method comprising detecting the presence of one or more mutations in exon 9 of the catalytic subunit of Phosphoinositol-3 kinase (PIK3CA or p110α) nucleic acid by

[0173] (a) contacting the nucleic acid in the sample from a patient with HER2-positive cancer with one or more of the following mutation-specific oligonucleotides:

[0174]

	(SEQ ID NO: 28)
	LATTTTQGAGAGAGGAUEUEGUGUAGAAAUUGEUUP
	(542 542K Mutation Probe);
	(SEQ ID NO: 30)
	JAATCACTAAGQAGGAGAAAGAUUUUEUAUGGAGUEP
	(545 545K Mutation Probe);
	(SEQ ID NO: 31)
	FCTGCGCQGGAGAAAGAUUUUEUAUGGAGUEAP
	(545 545A Mutation Probe);
	and/or
	(SEQ ID NO: 32)
	LCCTGCCCQGTGAUUUIAGAGAGAGGATCTCGP
	(545 545G Mutation Probe);

[0175] (b) (i) incubating the sample under conditions allowing hybridization of the oligonucleotide to the target sequence within the PI3KCA nucleic acid;

• • [0176] (ii) contacting the nucleic acid in the sample with one or both of the following oligonucleotides:

[0177]

	(SEQ ID NO: 25)
	UAAAAUUUAUUGAGAAUGUAUUUGCTTTTTC
	(542/545 Forward primer PIK3CA-9F13)
	and/or
	(SEQ ID NO: 26)
	TCCATTTTAGCACTTACCTGTGAC
	(542/545 Reverse primer PIK3CA-9R01);

• • [0178] (iii) generating an amplification product containing the target sequence within the PI3KCA nucleic acid;

[0179] (c) detecting hybridization

[0180] (d) identifying the patient as less likely to respond to a HER2 inhibitor if the presence of one or more mutations in exon 9 of the catalytic subunit of Phosphoinositol-3 kinase (PIK3CA or p110α) nucleic acid is detected.

[0181] The present invention is further illustrated by reference to the following non-limiting figures and examples.

[0197] Each standard 50-μL amplification reaction targeting one of the Exons 7, 9 or 20 included 100 ng genomic DNA, dNTPs (including dUTP), 0.05 U/μL Z05, DNA polymerase, 0.04 U/μL uracil-DNA glycosylase (UNG), and 200-400 nM forward and reverse primer (Table 1), 75-200 nM mutant and wild-type specific probes (Table 2). Amplification was performed in the Cobas® 4800 analyzer using the following temperature profile: 5 min at 50° C. followed by 55 cycles of 95° C. for 10 sec and 63° C. for 50 sec, followed by a single round of 40° C. for 2 min and 25° C. for 10 sec (melting curve analysis). Fluorescence data was collected during each amplification cycle and during the final melting curve analysis.

[0198]

TABLE A
Primer Sequences for the PIK3CA
Mutation Detection Test
Primer	Sequence 5′ to 3′
Codon 420	UUUUGGGGAAGAAAAGUGUUUUGAA
Forward Primer	(SEQ ID NO: 33)
PIK3CA-7F03
Codon 420	GATTCAAAGCCATTTTTCCAGATACTAGA
Reverse primer	(SEQ ID NO: 34)
PIK3CA-7R04
Codon 542/545	UAAAAUUUAUUGAGAAUGUAUUUGCTTTTTC
Forward primer	(SEQ ID NO: 25)
PIK3CA-9F13
Codon 542/545	TCCATTTTAGCACTTACCTGTGAC
Reverse primer	(SEQ ID NO: 26)
PIK3CA-9R01
Codon 1047	GAGGCTTTGGAGTATTTCATGAA
Forward primer	(SEQ ID NO: 35)
PIK3CA-20F01
Codon 1047	CCAATCCATTTTTGTTGTCCA
Reverse primer	(SEQ ID NO: 36)
PIK3CA-20R01
Key:
U = 5-propynyl dU

[0199]

TABLE B
Probe Sequences for the PIK3CA Mutation
Detection Test
Probe	Sequence 5′ to 3′
Codon 420 WT Probe	JCAATGGACAGQGUUEEUUAAAAAAEAA
	AGAAAAAUAUUP (SEQ ID NO: 37)
Codon 420 420R	OGAACACCQTCCAUUGGEAUGGGGAAAU
Mutation Probe	AUAAAP (SEQ ID NO: 38)
Codon 542 WT Probe	FTTTCAQAGAGAGGAUEUEGUGUAGAAA
	UUGEP (SEQ ID NO: 27)
Codon 542 542K	LATTTTQGAGAGAGGAUEUEGUGUAGAA
Mutation Probe	AUUGEUUP (SEQ ID NO: 28)
Codon 545 WT Probe	OCTGCTCAGTQAUUUIAGAGAGAGGATC
	TCGTGTP (SEQ ID NO: 29)
Codon 545 545K	JAATCACTAAGQAGGAGAAAGAUUUUEU
Mutation Probe	AUGGAGUEP (SEQ ID NO: 30)
Codon 545 545A	FCTGCGCQGGAGAAAGAUUUUEUAUGGA
Mutation Probe	GUEAP (SEQ ID NO: 31)
Codon 545 545G	LCCTGCCCQGTGAUUUIAGAGAGAGGAT
Mutation Probe	CTCGP (SEQ ID NO: 32)
Codon 1047 WT Probe	FTZCACATCQTZZTZZCTZZACAACAAP
	(SEQ ID NO: 39)
Codon 1047 1047R	LGACGTQCAUEAUUEAUUUGUUUEAUGP
Mutation Probe	(SEQ ID NO: 40)
Codon 1047 1047L	JGCACTTCATGQTGGCTGGACAACAAAA
Mutation Probe	AP (SEQ ID NO: 41)
Codon 1047 1047Y	OACCATGATATQCAUEAUUEAUUUGUUU
Mutation Probe	EP (SEQ ID NO: 42)
Key:
F = FAM Reporter Dye,
J = JA270 Reporter Dye,
O = CY5.5 Reporter Dye,
L = HEX Reporter Dye,
U = 5-propynyl dU,
E = 5-methyl dC,,
I = deoxyinosine,
Z = 7-deaza dG,
Q = BHQ2 Quencher Dye,
P = 3′ Phosphate

[0200] FIG. 6 shows Results of PIK3CA mutational analyses. PIK3CA mutations were in general associated with decreased sensitivity to HER2-targeted therapy in NeoSphere. Analyses per exon i.e. exons 7, 9 and 20 was carried out to explore in more detail the impact of specific mutations. For exon 9 mutations, out of 28 mutations detected across the 4 arms, 26 were found to be in the non-responder group. Exon 20 mutations had little impact on pCR. There were too few exon 7 mutations to draw conclusions.

[0201] While the invention has been described in detail with reference to specific examples, it will be apparent to one skilled in the art that various modifications can be made within the scope of this invention. Thus the scope of the invention should not be limited by the examples described herein, but by the claims presented below.

[0202] The present invention refers to the following nucleotide and amino acid sequences:

[0203] The sequences provided herein are available in the NCBI database and can be retrieved from the website at ncbi.nlm.nih.gov/sites/entrez?db=gene. These sequences also relate to annotated and modified sequences. The present invention also provides techniques and methods wherein homologous sequences, and, variants of the concise sequences provided herein are used. Preferably, such “variants” are genetic variants.

[0204] SEQ ID No. 1:

[0205] Nucleotide sequence encoding homo sapiens phosphoinositide-3-kinase, catalytic, alpha (PIK3CA), (NCBI accession number: NG_012113.1 GI:237858742).

[0206] SEQ ID No. 2:

[0207] Amino acid sequence of homo sapiens phosphatidylinositol-4,5-bisphosphate 3-kinase catalytic subunit. The sequence can be retrieved from the NCBI database under accession number NP_006209.2 GI:54792082 or from Uniprot database under accession number >sp|P42336|.

[0208] Positions 542 and 545 are indicated in bold letters.

[0209]

MPPRPSSGELWGIHLMPPRILVECLLPNGMIVTLECLREATLITIKHELFKEARKYPLHQ
LLQDESSYIFVSVTQEAEREEFFDETRRLCDLRLFQPFLKVIEPVGNREEKILNREIGFA
IGMPVCEFDMVKDPEVQDFRRNILNVCKEAVDLRDLNSPHSRAMYVYPPNVESSPELPKH
IYNKLDKGQIIVVIWVIVSPNNDKQKYTLKINHDCVPEQVIAEAIRKKTRSMLLSSEQLK
LCVLEYQGKYILKVCGCDEYFLEKYPLSQYKYIRSCIMLGRMPNLMLMAKESLYSQLPMD
CFTMPSYSRRISTATPYMNGETSTKSLWVINSALRIKILCATYVNVNIRDIDKIYVRTGI
YHGGEPLCDNVNTQRVPCSNPRWNEWLNYDIYIPDLPRAARLCLSICSVKGRKGAKEEHC
PLAWGNINLFDYTDTLVSGKMALNLWPVPHGLEDLLNPIGVTGSNPNKETPCLELEFDWF
SSVVKFPDMSVIEEHANWSVSREAGFSYSHAGLSNRLARDNELRENDKEQLKAISTRDPL
SEITEQEKDFLWSHRHYCVTIPEILPKLLLSVKWNSRDEVAQMYCLVKDWPPIKPEQAME
LLDCNYPDPMVRGFAVRCLEKYLTDDKLSQYLIQLVQVLKYEQYLDNLLVRFLLKKALTN
QRIGHFFFWHLKSEMHNKTVSQRFGLLLESYCRACGMYLKHLNRQVEAMEKLINLTDILK
QEKKDETQKVQMKFLVEQMRRPDFMDALQGFLSPLNPAHQLGNLRLEECRIMSSAKRPLW
LNWENPDIMSELLFQNNEIIFKNGDDLRQDMLTLQIIRIMENIWQNQGLDLRMLPYGCLS
IGDCVGLIEVVRNSHTIMQIQCKGGLKGALQFNSHTLHQWLKDKNKGEIYDAAIDLFTRS
CAGYCVATFILGIGDRHNSNIMVKDDGQLFHIDFGHFLDHKKKKFGYKRERVPFVLTQDF
LIVISKGAQECTKTREFERFQEMCYKAYLAIRQHANLFINLFSMMLGSGMPELQSFDDIA
YIRKTLALDKTEQEALEYFMKQMNDAHHGGWTTKMDWIFHTIKQHALN

[0210] SEQ ID No. 3:

[0211] Nucleotide sequence encoding exon 9 of homo sapiens phosphoinositide-3-kinase, catalytic, alpha (PIK3CA).

[0212]

AGTAACAGACTAGCTAGAGACAATGAATTAAGGGAAAATGACAAAGAAC

AGCTCAAAGCAATTTCTACACGATCCTCTCTCTGAAATCACTGAGCAGG

AGAAAGATTTTCTATGGAGTCACAG

[0213] SEQ ID No. 4:

[0214] Amino acid sequence encoded by exon 9 of homo sapiens phosphoinositide-3-kinase, catalytic, alpha (PIK3CA).

[0215] SEQ ID No. 5:

[0216] Amino acid sequence of the variable light (V_L) (FIG. 2A) domain of murine monoclonal antibody 2C4 (SEQ ID Nos. 5 and 6, respectively) as shown in FIG. 2.

[0217] SEQ ID No. 6:

[0218] Amino acid sequence of the variable heavy (V_H) (FIG. 2B) domain of murine monoclonal antibody 2C4 as shown in FIG. 2.

[0219] SEQ ID No. 7:

[0220] Amino acid sequence of the variable light (V_L) (FIG. 2A) domain of variant 574/Pertuzumab as shown in FIG. 2.

[0221] SEQ ID No. 8:

[0222] Amino acid sequence of the variable heavy (V_H) (FIG. 2B) domain of variant 574/Pertuzumab as shown in FIG. 2.

[0223] SEQ ID No. 9:

[0224] human V_L consensus frameworks (hum κ1, light kappa subgroup I; humIII, heavy subgroup III) as shown in FIG. 2.

[0225] SEQ ID No. 10:

[0226] human V_H consensus frameworks (hum id, light kappa subgroup I; humIII, heavy subgroup III) as shown in FIG. 2.

[0227] SEQ ID No. 11:

[0228] Amino acid sequences of Pertuzumab light chain as shown in FIG. 3A.

[0229] SEQ ID No. 12:

[0230] Amino acid sequences of Pertuzumab heavy chain as shown in FIG. 3B.

[0231] SEQ ID No. 13:

[0232] Amino acid sequence of Trastuzumab light chain domain as shown in FIG. 4A. Boundaries of the variable light domain are indicated by arrows.

[0233] SEQ ID No. 14:

[0234] Amino acid sequence of Trastuzumab heavy chain as shown in FIG. 4B. Boundaries of the variable heavy domain are indicated by arrows.

[0235] SEQ ID No. 15:

[0236] Amino acid sequence of variant Pertuzumab light chain sequence (FIG. 5A).

[0237] SEQ ID No. 16:

[0238] Amino acid sequence of variant Pertuzumab heavy chain sequence (FIG. 5B).

[0239] SEQ ID No. 17:

[0240] Nucleotide sequence encoding exon 9 of homo sapiens E542K mutant of phosphoinositide-3-kinase, catalytic, alpha (PIK3CA). The triplet (codon) encoding the mutant amino acid “K” at position 542 of the full-length amino acid sequence of PIKC3CA (see SEQ ID NO: 2 and FIG. 7) is highlighted in bold letters.

[0241]

AGTAACAGACTAGCTAGAGACAATGAATTAAGGGAAAATGACAAA

GAACAGCTCAAAGCAATTTCTACACGAGATCCTCTCTCTAAAATCACTGAG

CAGGAGAAAGATTTTCTATGGAGTCACAG

[0242] SEQ ID No. 18:

[0243] Amino acid sequence of homo sapiens E542K mutant of phosphoinositide-3-kinase, catalytic, alpha (PIK3CA). Position 542 is highlighted in bold. The mutant shows an increase in lipid kinase activity; oncogenic in vivo; occurs in the interface between the PIK3CA helical domain and the nSH2 (N-terminal SH2) region of the p85 regulatory subunit and may reduce the inhibitory effect of p85; requires interaction with RAS to induce cellular transformation.

[0244]

MPPRPSSGEL WGIHLMPPRI LVECLLPNGM IVTLECLREA TLITIKHELF KEARKYPLHQ
70         80         90        100        110        120
LLQDESSYIF VSVTQEAERE EFFDETRRLC DLRLFQPFLK VIEPVGNREE KILNREIGFA
130        140        150        160        170        180
IGMPVCEFDM VKDPEVQDFR RNILNVCKEA VDLRDLNSPH SRAMYVYPPN VESSPELPKH
190        200        210        220        230        240
IYNKLDKGQI IVVIWVIVSP NNDKQKYTLK INHDCVPEQV IAEAIRKKTR SMLLSSEQLK
250        260        270        280        290        300
LCVLEYQGKY ILKVCGCDEY FLEKYPLSQY KYIRSCIMLG RMPNLMLMAK ESLYSQLPMD
310        320        330        340        350        360
CFTMPSYSRR ISTATPYMNG ETSTKSLWVI NSALRIKILC ATYVNVNIRD IDKIYVRTGI
370        380        390        400        410        420
YHGGEPLCDN VNTQRVPCSN PRWNEWLNYD IYIPDLPRAA RLCLSICSVK GRKGAKEEHC
430        440        450        460        470        480
PLAWGNINLF DYTDTLVSGK MALNLWPVPH GLEDLLNPIG VTGSNPNKET PCLELEFDWF
490        500        510        520        530        540
SSVVKFPDMS VIEEHANWSV SREAGFSYSH AGLSNRLARD NELRENDKEQ LKAISTRDPL
550        560        570        580        590        600
LLDCNYPDPM VRGFAVRCLE KYLTDDKLSQ YLIQLVQVLK YEQYLDNLLV RFLLKKALTN
670        680        690        700        710        720
QRIGHFFEWH LKSEMHNKTV SQRFGLLLES YCRACGMYLK HLNRQVEAME KLINLTDILK
730        740        750        760        770        780
QEKKDETQKV QMKFLVEQMR RPDFMDALQG FLSPLNPAHQ LGNLRLEECR IMSSAKRPLW
790        800        810        820        830        840
LNWENPDIMS ELLFQNNEII FKNGDDLRQD MLTLQIIRIM ENIWQNQGLD LRMLPYGCLS
850        860        870        880        890        900
IGDCVGLIEV VRNSHTIMQI QCKGGLKGAL QFNSHTLHQW LKDKNKGEIY DAAIDLFTRS
910        920        930        940        950        960
CAGYCVATFI LGIGDRHNSN IMVKDDGQLF HIDFGHFLDH KKKKFGYKRE RVPFVLTQDF
970        980        990        1000       1010       1020
LIVISKGAQE CTKTREFERF QEMCYKAYLA IRQHANLFIN LFSMMLGSGM PELQSFDDIA
1030       1040       1050       1060
YIRKTLALDK TEQEALEYFM KQMNDAHHGG WTTKMDWIFH TIKQHALN

[0245] SEQ ID No.19:

[0246] Nucleotide sequence encoding exon 9 of homo sapiens E545K mutant of phosphoinositide-3-kinase, catalytic, alpha (PIK3CA). The triplet (codon) encoding the mutant amino acid “K” at position 545 of the full-length amino acid sequence of PIKC3CA (see SEQ ID NO: 2 and FIG. 7) is highlighted in bold letters.

[0247]

AGTAACAGACTAGCTAGAGACAATGAATTAAGGGAAAATGACAAA

GAACAGCTCAAAGCAATTTCTACACGAGATCCTCTCTCTGAAATCACTAAG

CAGGAGAAAGATTTTCTATGGAGTCACAG

[0248] SEQ ID No. 20:

[0249] Amino acid sequence of homo sapiens E545K mutant of phosphoinositide-3-kinase, catalytic, alpha (PIK3CA). Position 545 is highlighted in bold. The mutant shows an increase in lipid kinase activity: oncogenic in vivo; occurs in the interface between the PIK3CA helical domain and the nSH2 (N-terminal SH2) region of the p85 regulatory subunit and may reduce the inhibitory effect of p85; requires interaction with RAS to induce cellular transformation; enhances invadopodia-mediated extracellular matrix degradation and invasion in breast cancer cells.

[0250]

MPPRPSSGEL WGIHLMPPRI LVECLLPNGM IVTLECLREA TLITIKHELF KEARKYPLHQ
70         80         90        100        110        120
LLQDESSYIF VSVTQEAERE EFFDETRRLC DLRLFQPFLK VIEPVGNREE KILNREIGFA
130        140        150        160        170        180
IGMPVCEFDM VKDPEVQDFR RNILNVCKEA VDLRDLNSPH SRAMYVYPPN VESSPELPKH
190        200        210        220        230        240
IYNKLDKGQI IVVIWVIVSP NNDKQKYTLK INHDCVPEQV IAEAIRKKTR SMLLSSEQLK
250        260        270        280        290        300
LCVLEYQGKY ILKVCGCDEY FLEKYPLSQY KYIRSCIMLG RMPNLMLMAK ESLYSQLPMD
310        320        330        340        350        360
CFTMPSYSRR ISTATPYMNG ETSTKSLWVI NSALRIKILC ATYVNVNIRD IDKIYVRTGI
370        380        390        400        410        420
YHGGEPLCDN VNTQRVPCSN PRWNEWLNYD IYIPDLPRAA RLCLSICSVK GRKGAKEEHC
430        440        450        460        470        480
PLAWGNINLF DYTDTLVSGK MALNLWPVPH GLEDLLNPIG VTGSNPNKET PCLELEFDWF
490        500        510        520        530        540
SSVVKFPDMS VIEEHANWSV SREAGFSYSH AGLSNRLARD NELRENDKEQ LKAISTRDPL
550        560        570        580        590        600
LLDCNYPDPM VRGFAVRCLE KYLTDDKLSQ YLIQLVQVLK YEQYLDNLLV RFLLKKALTN
670        680        690        700        710        720
QRIGHFFFWH LKSEMHNKTV SQRFGLLLES YCRACGMYLK HLNRQVEAME KLINLTDILK
730        740        750        760        770        780
QEKKDETQKV QMKFLVEQMR RPDFMDALQG FLSPLNPAHQ LGNLRLEECR IMSSAKRPLW
790        800        810        820        830        840
LNWENPDIMS ELLFQNNEII FKNGDDLRQD MLTLQIIRIM ENIWQNQGLD LRMLPYGCLS
850        860        870        880        890        900
IGDCVGLIEV VRNSHTIMQI QCKGGLKGAL QFNSHTLHQW LKDKNKGEIY DAAIDLFTRS
910        920        930        940        950        960
CAGYCVATFI LGIGDRHNSN IMVKDDGQLF HIDFGHFLDH KKKKFGYKRE RVPFVLTQDF
970        980        990       1000       1010       1020
LIVISKGAQE CTKTREFERF QEMCYKAYLA IRQHANLFIN LFSMMLGSGM PELQSFDDIA
1030       1040       1050       1060
YIRKTLALDK TEQEALEYFM KQMNDAHHGG WTTKMDWIFH TIKQHALN

[0251] SEQ ID No.21:

[0252] Nucleotide sequence encoding exon 9 of homo sapiens E545A mutant of phosphoinositide-3-kinase, catalytic, alpha (PIK3CA). The triplet (codon) encoding the mutant amino acid “A” at position 545 of the full-length amino acid sequence of PIKC3CA (see SEQ ID NO: 2 and FIG. 7) is highlighted in bold letters.

[0253]

AGTAACAGACTAGCTAGAGACAATGAATTAAGGGAAAATGACAAA

GAACAGCTCAAAGCAATTTCTACACGAGATCCTCTCTCTGAAATCACTGCG

CAGGAGAAAGATTTTCTATGGAGTCACAG

[0254] SEQ ID No. 22:

[0255] Amino acid sequence of homo sapiens E545A mutant of phosphoinositide-3-kinase, catalytic, alpha (PIK3CA). Position 545 is highlighted in bold.

[0256]

MPPRPSSGEL WGIHLMPPRI LVECLLPNGM IVTLECLREA TLITIKHELF KEARKYPLHQ
70         80          90        100        110        120
LLQDESSYIF VSVTQEAERE EFFDETRRLC DLRLFQPFLK VIEPVGNREE KILNREIGFA
130        140        150        160        170        180
IGMPVCEFDM VKDPEVQDFR RNILNVCKEA VDLRDLNSPH SRAMYVYPPN VESSPELPKH
190        200        210        220        230        240
IYNKLDKGQI IVVIWVIVSP NNDKQKYTLK INHDCVPEQV IAEAIRKKTR SMLLSSEQLK
250        260        270        280        290        300
LCVLEYQGKY ILKVCGCDEY FLEKYPLSQY KYIRSCIMLG RMPNLMLMAK ESLYSQLPMD
310        320        330        340        350        360
CFTMPSYSRR ISTATPYMNG ETSTKSLWVI NSALRIKILC ATYVNVNIRD IDKIYVRTGI
370        380        390        400        410        420
YHGGEPLCDN VNIQRVPCSN PRWNEWLNYD IYIPDLPRAA RLCLSICSVK GRKGAKEEHC
430        440        450        460        470        480
PLAWGNINLF DYTDTLVSGK MALNLWPVPH GLEDLLNPIG VTGSNPNKET PCLELEFDWF
490        500        510        520        530        540
SSVVKFPDMS VIEEHANWSV SREAGFSYSH AGLSNRLARD NELRENDKEQ LKAISTRDPL
550        560        570        580        590        600
LLDCNYPDPM VRGFAVRCLE KYLTDDKLSQ YLIQLVQVLK YEQYLDNLLV RFLLKKALTN
670        680        690        700        710        720
QRIGHFFFWH LKSEMHNKTV SQRFGLLLES YCRACGMYLK HLNRQVEAME KLINLTDILK
730        740        750        760        770        780
QEKKDETQKV QMKFLVEQMR RPDFMDALQG FLSPLNPAHQ LGNLRLEECR IMSSAKRPLW
790        800        810        820        830        840
LNWENPDIMS ELLFQNNEII FKNGDDLRQD MLTLQIIRIM ENIWQNQGLD LRMLPYGCLS
850        860        870        880        890        900
IGDCVGLIEV VRNSHTIMQI QCKGGLKGAL QFNSHTLHQW LKDKNKGEIY DAAIDLFTRS
910        920        930        940        950        960
CAGYCVATFI LGIGDRHNSN IMVKDDGQLF HIDFGHFLDH KKKKFGYKRE RVPFVLTQDF
970        980        990       1000       1010       1020
LIVISKGAQE CTKTREFERF QEMCYKAYLA IRQHANLFIN LFSMMLGSGM PELQSFDDIA
1030       1040       1050       1060
YIRKTLALDK TEQEALEYFM KQMNDAHHGG WTTKMDWIFH TIKQHALN

[0257] SEQ ID No. 23:

[0258] Nucleotide sequence encoding exon 9 of homo sapiens E545G mutant of phosphoinositide-3-kinase, catalytic, alpha (PIK3CA). The triplet (codon) encoding the mutant amino acid “G” at position 545 of the full-length amino acid sequence of PIKC3CA (see SEQ ID NO: 2 and FIG. 7) is highlighted in bold letters.

[0259]

AGTAACAGACTAGCTAGAGACAATGAATTAAGGGAAAATGACAAA

GAACAGCTCAAAGCAATTTCTACACGAGATCCTCTCTCTGAAATCACTGGG

CAGGAGAAAGATTTTCTATGGAGTCACAG

[0260] SEQ ID No. 24:

[0261] Amino acid sequence of homo sapiens E545G mutant of phosphoinositide-3-kinase, catalytic, alpha (PIK3CA). Position 545 is highlighted in bold.

[0262]

MPPRPSSGEL WGIHLMPPRI LVECLLPNGM IVTLECLREA TLITIKHELF KEARKYPLHQ
70         80         90        100        110        120
LLQDESSYIF VSVTQEAERE EFFDETRRLC DLRLFQPFLK VIEPVGNREE KILNREIGFA
130        140        150        160        170        180
IGMPVCEFDM VKDPEVQDFR RNILNVCKEA VDLRDLNSPH SRAMYVYPPN VESSPELPKH
190        200        210        220        230        240
IYNKLDKGQI IVVIWVIVSP NNDKQKYTLK INHDCVPEQV IAEAIRKKTR SMLLSSEQLK
250        260        270        280        290        300
LCVLEYQGKY ILKVCGCDEY FLEKYPLSQY KYIRSCIMLG RMPNLMLMAK ESLYSQLPMD
310        320        330         340       350        360
CFTMPSYSRR ISTATPYMNG ETSTKSLWVI NSALRIKILC ATYVNVNIRD IDKIYVRTGI
370        380        390         400       410        420
YHGGEPLCDN VNTQRVPCSN PRWNEWLNYD IYIPDLPRAA RLCLSICSVK GRKGAKEEHC
430        440        450        460        470        480
PLAWGNINLF DYTDTLVSGK MALNLWPVPH GLEDLLNPIG VTGSNPNKET PCLELEFDWF
490        500        510        520        530        540
SSVVKFPDMS VIEEHANWSV SREAGFSYSH AGLSNRLARD NELRENDKEQ LKAISTRDPL
550        560        570        580        590        600
LLDCNYPDPM VRGFAVRCLE KYLTDDKLSQ YLIQLVQVLK YEQYLDNLLV RFLLKKALTN
670        680        690        700        710        720
QRIGHFFFWH LKSEMHNKTV SQRFGLLLES YCRACGMYLK HLNRQVEAME KLINLTDILK
730        740        750        760        770        780
QEKKDETQKV QMKFLVEQMR RPDFMDALQG FLSPLNPAHQ LGNLRLEECR IMSSAKRPLW
790        800        810        820        830        840
LNWENPDIMS ELLFQNNEII FKNGDDLRQD MLTLQIIRIM ENIWQNQGLD LRMLPYGCLS
850        860        870        880        890        900
IGDCVGLIEV VRNSHTIMQI QCKGGLKGAL QFNSHTLHQW LKDKNKGEIY DAAIDLFTRS
910        920        930        940        950        960
CAGYCVATFI LGIGDRHNSN IMVKDDGQLF HIDFGHFLDH KKKKFGYKRE RVPFVLTQDF
970        980        990       1000       1010       1020
LIVISKGAQE CTKTREFERF QEMCYKAYLA IRQHANLFIN LFSMMLGSGM PELQSFDDIA
1030       1040       1050       1060
YIRKTLALDK TEQEALEYFM KQMNDAHHGG WTTKMDWIFH TIKQHALN

[0263] All references cited herein are fully incorporated by reference. Having now fully described the invention, it will be understood by a person skilled in the art that the invention may be practiced within a wide and equivalent range of conditions, parameters and the like, without affecting the spirit or scope of the invention or any embodiment thereof.