Inavolisib for PIK3CA-mutated advanced endometrial cancer: a multicentric, phase II, MITO END-4 trial.

Abstract

BACKGROUND: The phosphatase and tensin homolog-phosphoinositide 3-kinase (PI3K)-protein kinase B (AKT) pathway is frequently altered in gynecological tumors, notably in endometrial cancer where PIK3CA mutations are found in nearly half of patients. Despite this, evidence of clinical activity of PI3K inhibitors in endometrial cancer is poor and limited. Alpelisib, an oral PI3K alpha-selective inhibitor, showed encouraging preliminary activity in advanced gynecological tumors harboring PIK3CA alterations. Inavolisib is a highly potent and selective PI3K inhibitor. PRIMARY OBJECTIVE(S): The MITO END-4 trial aims to assess the efficacy and safety of inavolisib in patients with endometrial cancer who have received platinum-based chemotherapy and immunotherapy. The primary objective is to determine the anti-tumor activity (assessed by objective response rate) of inavolisib in patients with advanced endometrial cancer with PIK3CA mutated tumors. STUDY HYPOTHESIS: The study tests the hypothesis that inavolisib has superior anti-tumor activity compared to historically available standard therapies in previously treated patients with advanced endometrial cancer harboring a PIK3CA mutation. TRIAL DESIGN: This is a phase II, single-arm, multicenter trial in which advanced endometrial cancer patients whose tumors harbor a pathogenic PIK3CA mutation will receive inavolisib. MAJOR INCLUSION/EXCLUSION CRITERIA: Patients aged 18 years and older with documented evidence of PIK3CA mutated advanced endometrial cancer (endometrioid, serous, clear cell, carcinosarcoma or mixed histology) will be enrolled. Patients have previously received at least 1 platinum-based chemotherapy in any setting (adjuvant or advanced) with or without immune checkpoint inhibitor, alone or in combination. Not more than 4 lines of therapy are allowed. Key exclusion criteria include uterine sarcoma and prior treatment with any PI3K, AKT, or mechanistic target of rapamycin (mTOR) inhibitor. PRIMARY ENDPOINT(S): Objective response rate defined as a complete response or partial response by the Investigator using RECIST v1.1 criteria over the whole treatment period. SAMPLE SIZE: 48 patients. ESTIMATED DATES FOR COMPLETING ACCRUAL: May 2028. TRIAL REGISTRATION: MITO END-4; EU-CT NUMBER: 2025-522981-61-00; NCT07522697.