Table 4. Clinical studies of PARP inhibitors in mCRPC with HRR mutations.

Study	Agent	Patients Enrolled	Key Findings
TOPARP-A [5]	Olaparib	Olaparib 49	Overall RR: 33% (16/49) RR in HRR positive subgroup: 88% (14/16) PFS: HRR+ve: 9.8 vs. HRR-ve: 2.7 months; P < 0.001 OS: HRR+ve: 13.8 vs. HRR-ve: 7.5 months; P = 0.05
TOPARP-B [20]	Olaparib 400 mg vs. Olaparib 300 mg (randomized 1:1)	Olaparib 400: 49 Olaparib 300: 49	RR: Olaparib 400 mg group: 54.3% vs. olaparib 300 mg group: 39.1% PFS: Olaparib 400 mg 5.5 months vs. olaparib 300 mg 5.4 months OS: Olaparib 400 mg 14.3 vs. olaparib 300 mg 10.1 months
PROFOUND [6]	Olaparib 300 mg vs. enzalutamide or Abi (pcNHA; randomized 2:1)	Cohort A+B: Olaparib: 256 vs. pcNHA: 131 Cohort A: Olaparib: 162 vs. pcNHA: 83	Cohort A+B RR: olaparib 22.0% vs. ADT 4.0% PFS: olaparib 5.8 vs. ADT 3.5 months OS: olaparib 17.5 vs. ADT 14.3 months Cohort A RR: olaparib 33.0% vs. ADT 2.0% PFS: olaparib 7.4 vs. ADT 3.6 months OS: olaparib 18.5 vs. ADT 15.1 months
TRITON2 (preliminary results) [19]	Rucaparib 600 mg	136	RR: 44% in patients with BRCA1/2 mutations Confirmed PSA response in 51.1% patients in BRCA1/2 group, 1 patient with a CDK12 alteration, 1 patient with a BRIP1 alteration, and 1 patient with a FANCA alteration
GALAHAD (preliminary results) [23]	Niraparib 300 mg	Total: 81; BRCA ½: 46 non-BRCA: 35	RR: BRCA ½ 41% vs. Non-BRCA 9% PFS: BRCA ½ 8.2 vs. Non-BRCA 5.3 months OS: BRCA ½ 12.6 vs. Non-BRCA 14
Clarke et al. 2018 [64]	Abi with Olaparib 300 mg or placebo (randomized 1:1)	Abi+Olaparib: 71 Abi+placebo: 71	RR: Abi+Olaparib 27% vs. Abi+placebo 32% PFS: Abi+Olaparib 13.8 vs. Abi+placebo 8.2 months OS: Abi+Olaparib 22.7 Abi+placebo 20.9 months

Abbreviations: Abi: abiraterone; HRR: homologous recombination repair; OS: overall survival; pcNHA: physician choice novel hormonal agent (abiraterone or enzalutamide); PFS: progression-free survival; RR: response rate.