Background: In ARIEL3, pts were randomized 2:1 (oral rucaparib 600 mg or placebo). Rucaparib significantly improved progression-free survival (PFS) vs placebo in all primary analysis groups (Coleman et al. Lancet. 2017;390:1949-61). An exploratory subgroup analysis of ARIEL3 pts with or without bulky residual disease ( > 2 cm per blinded independent central review [BICR]) at baseline is reported. Methods: Pts were assigned to 2 analysis subgroups: with or without bulky residual disease at baseline. PFS was assessed in 3 predefined cohorts: BRCA mutant; homologous recombination deficient (HRD) (BRCA mutant or BRCA wild type/high loss of heterozygosity); and intent-to-treat (ITT) population. Results: PFS data for each subgroup (visit cutoff date 15 Apr 2017) by status of bulky disease at baseline are summarized in the Table. Safety data were consistent with data reported previously. In the rucaparib arm, the most common grade ≥3 treatment-emergent adverse event in pts with and pts without bulky disease was anemia (20.0% and 18.5%, respectively). Clinical trial information: NCT01968213  Conclusions: Rucaparib improved PFS vs placebo in all 3 predefined cohorts for both pts with and without bulky residual disease. PFS benefit with rucaparib was largest in pts with BRCA-mutant rOC.

*Stratified log-rank P value.