CAPTURE: A phase II trial evaluating alpelisib fulvestrant vs capecitabine in advanced breast cancer patients with PIK3CA-mutant circulating DNA following CDK4/6 inhibition.

Abstract

1064Background: PIK3CA mutations are a key therapeutic target in ER+ advanced breast cancer (ABC) readily detectable through circulating tumor DNA (ctDNA). The PI3Kα inhibitor alpelisib is approved in ER+ HER2- ABC but it remains unclear when to incorporate it into the current treatment algorithm. To address this, we conducted a phase II study assessing superiority of alpelisib + fulvestrant vs capecitabine in ABC pts with detectable PIK3CA mutant ctDNA following CDK4/6i plus aromatase inhibition (AI). Methods: Eligible pts had ER+ HER2- ABC, prior progression on CDK4/6i+AI and PIK3CA mutations detected via ctDNA ddPCR. Pts were randomized 1:1 to receive alpelisib (300mg daily) + fulvestrant..