Abstract 46P
Background
The role of PI3K pathway aberrations in the clinical behavior and therapy responsiveness of hormone receptor–positive (HR+/HER2-) tumors remains controversial. Some authors suggested that mutations may be related to poor clinical outcomes, although this was reported in heterogeneous populations or only patients with early-stage disease. There is therefore a need to better understand the prognostic implications of PIK3CA mutations in advanced breast cancer (ABC). To this purpose, in this study, we analyzed patient data from a Latin-American population concerning overall survival (OS) and progression free survival (PFS).
Methods
Retrospective cohort of HR+/HER2- ABC patients, from public and private facilities in Argentina. Patients were included if PIK3CA was tested in metastatic setting. PIK3CA determination was carried out by PCR, NGS or commercially available multigenetic platforms. Kaplan-Meier method was used for survival analysis. Multivariate analysis was done with Cox regression analysis.
Results
155 patients were analyzed (Median age 53.0, IQR 43-61.75). 39.4% (61) presented PIK3CA mutation. De novo metastatic patients covered 23.9% (37) of the sample. 74.8% (116) received CDK inhibitors added to hormone therapy (CDKi-HT) in the first-line (1L) setting. In second-line (2L) setting, 48% (48) received a combination of HT and other molecules (CDKi, Alpelisib, Everolimus), 40% (40) chemotherapy and 12% (12) HT. With a median follow-up of 42.1 months (IQR 26.9-63.8), OS analysis showed no difference according to PIK3CA status (HR 0.76. CI95% 0.40-1.47, p=0.4). 1L PFS was 23.0 months vs 22.1 months for patients with WT and PI3KCA mutated tumors, respectively (HR 0.97; CI95% 0.65-1.44; p=0.9). The observed 2L PFS was 10.6 months vs 11.1 months (HR 0.96; CI95% 0.60-1.53; p=0.9). After adjusting results by other prognostic variables, no difference was observed in survival results.
Conclusions
In our real-world study, no difference was observed in OS and PFS according to PIK3CA mutation presence, highlighting its lack of prognostic value. Local data from Latin America is important to uncover tumor characteristics in these populations.
Legal entity responsible for the study
The authors.
Funding
Has not received any funding.
Disclosure
All authors have declared no conflicts of interest.