ATHENA-MONO (GOG-3020/ENGOT-ov45): A randomized, double-blind, phase 3 trial evaluating rucaparib monotherapy versus placebo as maintenance treatment following response to first-line platinum-based chemotherapy in ovarian cancer

LBA5500 Background: While PARP inhibitors have shown efficacy as first-line (1L) maintenance treatment for patients (pts) with ovarian cancer (OC), questions remain about the pt population that may benefit from their use. ATHENA (NCT03522246) was designed to test if rucaparib may be effective as 1L maintenance treatment in a broad pt population, including those without BRCA mutations or other evidence of homologous recombination deficiency (HRD), or high-risk clinical characteristics such as residual disease. Here we report results from the ATHENA–MONO comparison of rucaparib vs placebo. Methods: Pts with stage III–IV high-grade OC who had completed cytoreductive surgery (R0 permitted) and 4–8 cycles of 1L platinum-doublet (bevacizumab allowed with chemotherapy) with a response were randomized 4:1 to oral rucaparib 600 mg BID or placebo. Pts were stratified by HRD status (as determined by FoundationOne CDx), residual disease status after chemotherapy, and timing of surgery. The primary endpoint of investigator-assessed PFS per RECIST was assessed in a step-down procedure first in the HRD population (BRCA mutant or BRCA wild-type/loss of heterozygosity [LOH] high carcinoma) and then in the intent-to-treat (ITT) population. Blinded independent central review (BICR)–assessed PFS was a stand-alone, secondary endpoint. PFS in BRCA mutant and HRD-negative pts (BRCA wild-type/LOH low) were exploratory endpoints. Results: As of Mar 23, 2022 (visit cutoff), 427 and 111 pts were randomized to rucaparib monotherapy or placebo (median time on treatment, 14.7 and 9.9 mo). PFS data are shown in the Table. Most common grade ≥3 TEAEs were anemia (rucaparib, 28.7% vs placebo, 0%), neutropenia (14.6% vs 0.9%), and ALT/AST increased (10.6% vs 0.9%). Rucaparib dose reduction, interruption, and discontinuation due to TEAEs occurred in 49.4%, 60.7%, and 11.8% of pts. Conclusions: Rucaparib monotherapy is effective as 1L maintenance with significant benefit vs placebo observed in the ITT and HRD populations, as well as the non-nested subgroup of pts without known HRD. Clinical trial information: NCT03522246. [Table: see text]