Alliance A092104: A randomized phase 2/3 study of olaparib plus temozolomide versus investigator’s choice for the treatment of patients with advanced uterine leiomyosarcoma after progression on prior chemotherapy.

Abstract

11507 Background: Advanced uterine leiomyosarcoma (uLMS) is an aggressive malignancy with poor prognosis. Standard-of-care treatments, including trabectedin (Tb) or pazopanib (P), provide median progression-free survival (PFS) of 3-4 months (mo) and objective response rates (ORR) of ~11%. Homologous recombination deficiency (HRD) in a subset of uLMS supports the use of PARP inhibitors combined with DNA-damaging agents. Preclinical studies demonstrated synergistic activity of olaparib and temozolomide (T+O), and a prior single-arm Phase II study of T+O showed promising efficacy independent of an established biomarker, warranting further investigation in a randomized setting. Methods: Alliance A092104 is a Phase II/III trial evaluating olaparib (200 mg BID) plus temozolomide (75 mg/m² daily, days 1-7, every 21 days) versus investigator’s choice of Tb or P in patients (pts) with advanced uLMS who progressed on ≥2 prior systemic therapies. Stratification factors included ECOG (0-1 vs. 2) and prior lines (2 vs. ≥3). The Phase II (Phase III) primary endpoint was PFS (OS), with a planned suspension of accrual at the end of Phase II. A total of 70 evaluable pts (58 PFS events) were needed to detect an improvement in PFS from 4 vs. 8 mo with power of 90% and 1-sided type I error of 10%, with futility assessed after 29 PFS events. Upon meeting the Phase II futility threshold for PFS, the trial was permanently closed. Data were released from the data and safety monitoring board. Pts continue to be followed for outcomes. Results: 74 pts enrolled (Arm 1: T+O, n = 37; Arm 2: investigator’s choice, n = 37 (Tb, 18; P, 13; 6 pts did not start treatment). The arms were balanced for baseline demographics except race, with the T+O arm having a higher proportion of black/African American (29.7% vs. 16.2%). 21 pts remain on treatment. Hematologic adverse events (AEs) were more frequent in the T+O arm, with Grade 4 neutropenia (19.5%) and thrombocytopenia (8.3%) both managed by dose reductions. Non-hematologic Grade 3 AEs were higher in the investigator’s choice arm (45.2% vs. 13.9%). No Grade 5 AEs were reported. In the first 70 pts, with a median follow-up of 5.9 mo, and 39 total PFS events, the median PFS was 3.2 mo (95% CI: 2.0-NE) for T+O versus 5.6 mo (95% CI: 2.8-NE) for investigator’s choice (HR = 1.00; 95% CI: 0.60-2.17; 1-sided stratified log rank p = 0.50). Within Arm 2, the median PFS for Tb and P were respectively 5.6 (95% CI: 3.1-NE) and 3.8 (95% CI: 1.5-NE) mo. 3 pts in the T+0 arm and 1 patient in the investigator’s choice arm (Tb) had a confirmed partial response. Conclusions: The trial did not meet its primary endpoint of PFS in Phase II. This suggests that a biomarker may be needed before there is further exploration of PARP inhibitor-based regimens in uLMS. Overall survival and analysis of tissue-based biomarkers will be presented. Clinical trial information: NCT05432791 .