PIK3CA testing in hormone receptor-positive/HER2-negative metastatic breast cancer: real-world data from Italian molecular pathology laboratories

Abstract

Introduction: PIK3CA gene mutations occur in approximately 40% of hormone receptor-positive/HER2-negative (HR⁺/HER2⁻) metastatic breast cancers (MBCs), electing them to targeted therapy. Testing PIK3CA status is complex due to selection of biological specimen and testing method. Materials & methods: This work investigates real-life experience on PIK3CA testing in HR⁺/HER2⁻ MBC. Clinical, technical and molecular data on PIK3CA testing were collected from two referral laboratories. Additionally, the results of a nationwide PIK3CA survey involving 116 institutions were assessed. Results: Overall, n = 35 MBCs were PIK3CA-mutated, with mutations mostly occurring in exons 9 (n = 19; 51.4%) and 20 (n = 15; 40.5%). The nationwide survey revealed significant variability across laboratories in terms of sampling methodology, technical assessment and clinical report signing healthcare figures for PIK3CA molecular testing in diagnostic routine practice. Conclusion: This study provides insights into the real-world routine of PIK3CA testing in HR⁺/HER2⁻ MBC and highlights the need for standardization and networking in predictive pathology.

Keywords: :

• breast cancer
• molecular testing
• PIK3CA

Supplementary data

To view the supplementary data that accompany this paper please visit the journal website at: www.tandfonline.com/doi/suppl/10.2217/pgs-2023-0238

Financial disclosure

The authors have no financial involvement with anyorganization or entity with a financial interest in or financial conflict with the subject matter or materials discussed in the manuscript. This includes employment, consultancies, honoraria, stock ownership or options, expert testimony, grants or patents received or pending, or royalties.

Competing interests disclosure

F Pepe has received honoraria for consulting, advisory role, speaker bureau, travel and/or research grants from Menarini; P Pisapia from Novartis; F Pagni from MSD, Novartis, Roche and Amgen Lilly, Diapath, Logibiotech; G Troncone from Roche, MSD, Pfizer, Boehringer Ingelheim, Eli Lilly, BMS, GSK, Menarini, AstraZeneca, Amgen and Bayer; C De Angelis from Roche, AstraZeneca, Lilly, GSK, Novartis, Seagen and Pfizer; G Curigliano from BMS, Roche, Pfizer, Novartis, Lilly, Astra Zeneca, Daichii Sankyo, Merck, Seagen, Ellipsis, Gilead, Menarini and Novartis; E Guerini Rocco from Thermo Fisher Scientific, Novartis, AstraZeneca, Roche, Biocartis and Illumina; U Malapelle from Boehringer Ingelheim, Roche, Merck Sharpe & Dohme, Amgen, Thermo-Fisher Scientific, Eli Lilly & Company, Diaceutics, GlaxoSmithKline, Merck, AstraZeneca, Janssen, Diatech, Novartis and Hedera; N Fusco from Merck Sharp & Dohme, Novartis, AstraZeneca, Roche, Menarini, Daiichi Sankyo, GlaxoSmithKline, Gilead, Diaceutics, Adicet Bio, Sermonix, Reply and Leica Biosystems unrelated to the current work. The authors have no other competing interests or relevant affiliations with any organization or entity with the subject matter or materials discussed in the manuscript apart from those disclosed.

Writing disclosure

No writing assistance was utilized in the production of this manuscript.

Informed consent

The study was conducted in accordance with the Declaration of Helsinki and approved by the Institutional Ethics Committee of European Institute of Oncology IRCCS, Milan, Italy under the approval number #UID3472, approved on 16 December 2021; according to the European Union’s General Data Protection Regulation (GDPR), all information regarding the recruited patients were pseudoanonymized. Written informed consent was acquired from all patients and documented according to The Italian Data Protection Authority (www.garanteprivacy.it/web/guest/home/docweb/-/docwebdisplay/export/2485392).