Abstract 439P
Background
PIK3CA mutations have been identified in approximately up to 40% of breast cancer cases and PIK3CA targeting has already been incorporated in treatment algorithms, especially in the second line of ER+/HER2- patients. HeSMO launched a national program to provide PIK3CA mutation testing, which is officially not reimbursed, with the aim to identify mutations in the PIK3CA gene, and, therefore, lead to more therapeutic options.
Methods
All HR+/HER2- patients with a diagnosis of metastatic breast cancer were eligible to participate in this program. The result of the test was obtained using the COBAS® PIK3CA method, a diagnostic test specifically designed to detect mutations in the PIK3CA gene in tumor tissue samples (FFPE) attained by biopsy or surgically, which detects 17 different mutations in the PIK3CA gene, including the most commonly occurring in Exons 9 and 20.
Results
From June 2022 to March 2023, 149 patients from across the country were tested within this program. Sixty one (61) patients (40.94%) were detected with mutation in PIK3CA gene and 88 (59.06%) without mutation (Table). 23 patients had Exon 9 mutations (37.70%), 33 in Exon 20 (54.10%), and 8 had mutations in the remaining Exons 1, 4 and 7 (13.11%). In 1 sample 4 mutations were detected: (Exon 7/9/20), and 2 mutations in another 2 samples (Exon 9: E545X, Q546X and Exons 1/20), while in all other samples just 1 mutation was detected in each.
Table: 439P
PIK3CA mutation results of HeSMO’s program
Exon | Mutation | Samples | Mutation percentage in all patients detected with PIK3CA gene mutation (61) | Mutation percentage in all patients tested (149) |
Exon 1 | R88Q | 2 | 3,28% | 1,34% |
Exon 4 | N345K | 3 | 4,92% | 2,01% |
Exon 7 | C420R | 3 | 4,92% | 2,01% |
Exon 9 | E542K | 7 | 11,48% | 4,70% |
Exon 9 | E545X | 12 | 19,67% | 8,05% |
Exon 9 | Q546X | 2 | 3,28% | 1,34% |
Exon 9 | E545X, Q546X | 1 | 1,64% | 0,67% |
Exon 9 | E542K, E545X | 1 | 1,64% | 0,67% |
Exon 20 | H1047X | 32 | 52,46% | 21,48% |
Exon 20 | G1049R | 1 | 1,64% | 0,67% |
Conclusions
In our series, 40.94% of the patients tested, were detected with mutations in PIK3CA gene, in accordance with published data. Apart from the significant implications for treatment possibilities in a substantial patients’ population, these results provide valuable epidemiological data and strengthen our efforts for reimbursement of PIK3CA mutation testing in Greece.
Clinical trial identification
Editorial acknowledgement
Legal entity responsible for the study
Hellenic Society of Medical Oncology (HeSMO).
Funding
Has not received any funding.
Disclosure
A. Koumarianou: Financial Interests, Institutional, Research Grant: Merck. G. Kesisis: Financial Interests, Personal, Invited Speaker: Bristol, MSD, Amgen, AZ, Galenica, Pfizer, Ipsen, Sanofi; Financial Interests, Personal, Advisory Board: Gilead, Novartis, Roche, Boehringer. E.A. Sogka: Financial Interests, Institutional, Invited Speaker, Invited speaker in a Greek conference: Merck. N.G. Tsoukalas: Financial Interests, Personal, Invited Speaker: Servier, Leo, Janssen, Ipsen, BMS, Gilead; Financial Interests, Personal, Advisory Board: Pfizer, Merck, Roche. N. Chatzifoti: Financial Interests, Personal, Full or part-time Employment: Hellenic Society of Medical Oncology (HeSMO). All other authors have declared no conflicts of interest.
Resources from the same session
423P - A real-world study on the clinical value of apatinib-based regimens in metastatic triple-negative breast cancer
Presenter: Huang wei
Session: Poster session 03
424P - Pyrotinib plus capecitabine for trastuzumab-resistant, HER2-positive advanced breast cancer: Updated survival results from the phase II PICTURE trial
Presenter: Xichun Hu
Session: Poster session 03
425P - Real world quality of life (QoL) in breast cancer (BC) patients treated with cyclin-dependent kinase 4/6 inhibitors (CDK4/6i)
Presenter: Blanca Tavara
Session: Poster session 03
427P - Pyrotinib plus trastuzumab versus pertuzumab plus trastuzumab in patients with HER2-positive metastatic breast cancer: A multicenter, retrospective study
Presenter: biyun Wang
Session: Poster session 03
428P - Palbociclib dose patterns in Swedish patients with metastatic breast cancer: 5-year update from the SIRI study
Presenter: Antonis Valachis
Session: Poster session 03
429P - The impact of HER2 status on the efficacy of CDK 4/6 inhibitors: A multicenter study
Presenter: Hasan Yildirim
Session: Poster session 03
430P - Real-world patient characteristics and treatment patterns in HR+/HER2+ metastatic breast cancer patients in 5 European countries
Presenter: Carmen Criscitiello
Session: Poster session 03
431P - Distribution and prognostic role of HER2 status of circulating tumor cells (CTCs) and tumor-derived extracellular vesicles (tdEVs) in HER2- metastatic breast cancer (MBC) patients (pts)
Presenter: Eleonora Nicolo
Session: Poster session 03
432P - Ki67 and progesterone receptor status could be predict sensitivity to cyclin-dependent kinase inhibitor
Presenter: Lucia Navarro Berlanga
Session: Poster session 03