Association of location of BRCA1 and BRCA2 mutations with benefit from olaparib and bevacizumab maintenance in high-grade ovarian cancer: phase III PAOLA-1/ENGOT-ov25 trial subgroup exploratory analysis

BACKGROUND

In the phase III PAOLA-1 study, the addition of maintenance olaparib to bevacizumab in patients with newly diagnosed high-grade ovarian cancer (HGOC) resulted in prolonged progression-free survival (PFS), particularly for homologous recombination deficiency-positive tumors, including those with a BRCA mutation (BRCAm). The magnitude of benefit from olaparib and bevacizumab according to the location of mutation in BRCA1/BRCA2 remains to be explored.

PATIENTS AND METHODS

Patients with advanced-stage HGOC responding after platinum-based chemotherapy + bevacizumab received maintenance therapy bevacizumab (15 mg/kg q3w for 15 months) + either olaparib (300 mg b.i.d. for 24 months) or placebo. PFS was analyzed in the subgroup of patients with BRCA1m/BRCA2m according to mutation location in the functional domains of BRCA1 [Really Interesting Gene (RING), DNA-binding domain (DBD), or C-terminal domain of BRCA1 (BRCT)] and BRCA2 [RAD51-binding domain (RAD51-BD); DBD].

RESULTS

From 806 randomized patients, 159 harbored BRCA1m (19.7%) and 74 BRCA2m (9.2%). BRCA1m in RING, DBD, and BRCT domains was detected in 18, 40, and 33 patients, and BRCA2m in RAD51-BD and DBD in 36 and 13 patients, respectively. After a median follow-up of 25.5 months, benefit from maintenance olaparib + bevacizumab was observed irrespective of location of BRCAm. The benefit was particularly high for those with BRCA1m located in the DBD, with 24-month PFS estimated to be 89% and 15% [olaparib + bevacizumab versus placebo + bevacizumab hazard ratio = 0.08 (95% confidence interval 0.02-0.28); interaction P = 0.03]. In BRCA2m patients, 24-month PFS rates for those with mutations located in the DBD were 90% and 100% (olaparib + bevacizumab versus placebo + bevacizumab), respectively.

CONCLUSIONS

Advanced-stage BRCA-mutated HGOC patients reported PFS benefit from maintenance olaparib and bevacizumab regardless of mutation location. The benefit is particularly high for patients with mutations located in the DBD of BRCA1. Mutations located in the DBD of BRCA2 are also associated with excellent outcome.

Feasibility Study of a Network Meta-Analysis and Unanchored Population-Adjusted Indirect Treatment Comparison of Niraparib, Olaparib, and Bevacizumab as Maintenance Therapies in Patients with Newly Diagnosed Advanced Ovarian Cancer

Selecting a first-line (1L) maintenance option for ovarian cancer is challenging given the variety of therapies, differing trials, and the lack of head-to-head data for angiogenesis and poly(ADP-ribose) polymerase (PARP) inhibitors. Thus, indirect treatment comparisons (ITCs) can aid treatment decision making. This study assessed the feasibility of two ITCs, a network meta-analysis (NMA) and a population-adjusted ITC (PAIC), comparing the efficacy of the PARP inhibitor niraparib in the PRIMA trial (NCT02655016) with other 1L maintenance treatments. A systematic literature review was conducted to identify trials using the Cochrane Handbook for Systematic Reviews of Interventions to assess differences in trial design, population characteristics, treatment arms, and outcome measures. All 12 trials identified were excluded from the NMA due to the absence of a common comparator and differences in survival measures and/or inclusion criteria. The PAIC comparing PRIMA and PAOLA-1 trials was also not feasible due to differences in inclusion criteria, survival measures, and the previous receipt of chemotherapy/bevacizumab. Neither ITC met recommended guidelines for analysis; the results of such comparisons would not be considered appropriate evidence when selecting 1L maintenance options in ovarian cancer. ITCs in this setting should be performed cautiously, as many factors can preclude objective trial comparisons.

The forefront of ovarian cancer therapy: update on PARP inhibitors

BACKGROUND

In recurrent ovarian cancer, poly(ADP-ribose) polymerase (PARP)-inhibiting agents have transformed the treatment of platinum-sensitive disease. New data support use of PARP inhibitors earlier in the treatment algorithm.

DESIGN

We review results from recent phase III trials evaluating PARP inhibitors as treatment and/or maintenance therapy for patients with newly diagnosed ovarian cancer. We discuss the efficacy and safety of these agents in the all-comer and biomarker-selected populations studied in clinical trials, and compare the strengths and limitations of the various trial designs. We also consider priorities for future research, with a particular focus on patient selection and future regimens for populations with high unmet need.

RESULTS

Four phase III trials (SOLO-1, PAOLA-1/ENGOT-OV25, PRIMA/ENGOT-OV26 and VELIA/GOG-3005) demonstrated remarkable improvements in progression-free survival with PARP inhibitor therapy (olaparib, niraparib or veliparib) for newly diagnosed ovarian cancer. Differences in trial design (treatment and/or maintenance setting; single agent or combination; bevacizumab or no bevacizumab), patient selection (surgical outcome, biomarker eligibility, prognosis) and primary analysis population (intention-to-treat, BRCA mutated or homologous recombination deficiency positive) affect the conclusions that can be drawn from these trials. Overall survival data are pending and there is limited experience regarding long-term safety.

CONCLUSIONS

PARP inhibitors play a pivotal role in the management of newly diagnosed ovarian cancer, which will affect subsequent treatment choices. Refinement of testing for patient selection and identification of regimens to treat populations that appear to benefit less from PARP inhibitors are a priority.