Abstract PR06: ARIEL3: A phase 3, randomized, double-blind study of rucaparib vs placebo following response to platinum-based chemotherapy for recurrent ovarian cancer (OC)

Background: Rucaparib, a poly(ADP-ribose) polymerase (PARP) inhibitor, is approved in the United States for treatment of women with deleterious BRCA mutation (germline and/or somatic) associated advanced OC who have been treated with two or more chemotherapies. Rucaparib has also demonstrated antitumor activity in the treatment setting in patients (pts) with BRCA wild-type associated recurrent OC whose tumor has high genomic loss of heterozygosity (LOH). ARIEL3 evaluated rucaparib vs placebo as maintenance treatment in pts with recurrent platinum-sensitive OC. Methods: Eligible pts received ≥2 prior platinum-based therapies, had platinum-sensitive OC (disease progression ≥6 mo after penultimate platinum), and achieved a complete response (RECIST v1.1) or partial response (RECIST v1.1 or Gynecologic Cancer InterGroup CA-125 criteria) to their most recent platinum. All pts were required to have CA-125 less than the upper limit of normal. Pts were randomized 2:1 to receive oral rucaparib 600 mg BID or placebo. Investigator-assessed progression-free survival (PFS) (primary endpoint) was assessed in a step-down procedure for 3 nested cohorts: (1) BRCA mutant (deleterious germline or somatic BRCA mutation); (2) homologous recombination deficient (HRD) (BRCA mutant or BRCA wild type/LOH high); and (3) intent-to-treat (ITT) population. PFS was also assessed by blinded independent central review (BICR) (secondary endpoint) and LOH status in pts with BRCA wild type OC (exploratory endpoint). Adverse events (AEs) were summarized descriptively. Results: ARIEL3 enrolled 564 pts (375, rucaparib; 189, placebo). Nearly 200 pts (n=196) had BRCA mutation-associated OC. Of these pts, 130 had a germline BRCA mutation (82 [21.9%], rucaparib; 48 [25.4%], placebo), 56 had a somatic BRCA mutation (40 [10.7%], rucaparib; 16 [8.5%], placebo), and 10 pts had tumors with germline and/or somatic BRCA status unknown (8 [2.1%], rucaparib; 2 [1.1%], placebo). Median investigator-assessed PFS in the BRCA-mutant cohort (130, rucaparib; 66 placebo) was 16.6 mo vs 5.4 mo (hazard ratio [HR], 0.23; 95% confidence interval [CI], 0.16-0.34; P