388TiPAlpelisib (ALP) + endocrine therapy (ET) by last prior therapy in patients (pts) with PIK3CA-mutated hormone-receptor positive (HR+) human epidermal growth factor receptor-2-Negative (HER2 –) advanced breast cancer (ABC): Additional study cohort in BYLieve

AbstractBackgroundApproximately 40% of pts with HR+, HER2 – ABC have mutations (mut) in PIK3CA, which encodes α-PI3K and leads to PI3K pathway hyperactivation and potentially ET resistance. ALP is a selective inhibitor of α-PI3K that, in combination with fulvestrant (FUL), significantly improved median progression-free survival (PFS) vs placebo + FUL i n pts with PIK3CA-mut, HR+ HER2– ABC in the phase 3 SOLAR-1 trial (11.0 vs 5.7 mo, respectively; HR 0.65; 95% CI, 0.50-0.85; P <  0.001). BYLieve is an ongoing phase 2, multicenter, open-label, noncomparative study assessing ALP + ET (FUL or letrozole [LET]) in pts with PIK3CA-mut HR+, HER2– ABC who progressed on/after prior treatments (tx).Trial designBYLieve includes women (any menopausal status) and men with PIK3CA-mut, HR+, HER2 – ABC and evidence of tumor progression on prior tx. Cohorts A and B comprise pts who received a cyclin-dependent kinase 4/6 inhibitor (CDK4/6i) + ET as their last tx. With the adoption of Amendment 3, a new cohort (C) enrolls pts who had systemic chemotherapy or ET as last prior tx and who failed aromatase inhibitor (AI) in the adjuvant or metastatic setting. In the advanced setting, ≤2 anticancer tx (including ≤1 chemotherapy) are allowed. Pts must have ≥1 measurable lesion per RECIST criteria or ≥ 1 predominantly lytic bone lesion. Key exclusion criteria include prior PI3Ki tx and type 1 or uncontrolled type 2 diabetes. Study tx comprises: Cohort A (prior CDK 4/6i +...
Source: Annals of Oncology - Category: Cancer & Oncology Source Type: research