Christina Washington

Effectiveness of PARP Inhibitor Maintenance Therapy in Ovarian Cancer by BRCA1/2 and a Scar-Based HRD Signature in Real-World Practice

Abstract Purpose: The purpose of the study was to compare the effectiveness of PARP inhibitor maintenance therapy (mPARPi) in real-world practice by biomarker status [BRCA1/2 alterations (BRCAalt) and a homologous recombination deficiency signature (HRDsig)] in advanced ovarian cancer. Experimental Design: Patients with ovarian cancer receiving first-line platinum-based chemotherapy and either mPARPi or no maintenance were included. Patient data were obtained by a US-based de-identified ovarian cancer Clinico-Genomic Database, from ∼280 US cancer clinics (01/2015–03/2023). Real-world progression-free survival (rwPFS) and overall survival (rwOS) were compared by biomarker status using Cox models, weighted by propensity scores. Results: Of 673 patients, 160 received mPARPi [31.2% BRCAalt and 51.9% HRDsig(+)] and 513 no maintenance [15.6% BRCAalt and 34.1% HRDsig(+)]. BRCAalt patients receiving mPARPi versus no maintenance had favorable rwPFS [HR, 0.48; 95% confidence interval (CI), 0.26–0.87; P = 0.0154], as did BRCA wild-type (WT; HR, 0.76; 95% CI, 0.57–1.01; P = 0.0595). Favorable rwOS was not observed with mPARPi for BRCAalt or BRCA-WT. HRDsig(+) patients receiving mPARPi versus no maintenance had favorable rwPFS (HR, 0.36; 95% CI, 0.24–0.55; P < 0.001) and numerically favorable rwOS (HR, 0.46; 95% CI, 0.21–1.02; P = 0.0561). No differences were observed for HRDsig(−). mPARPi treatment interaction was observed for HRDsig(+) versus HRDsig(−) (rwPFS P < 0.001/rwOS P = 0.016) but not for BRCAalt versus BRCA-WT. Patients with BRCA-WT/HRDsig(+) receiving mPARPi had favorable rwPFS (HR, 0.40; 95% CI, 0.22–0.72; P = 0.003), whereas no difference was observed for BRCA-WT/HRDsig(−). Conclusions: HRDsig predicted benefit of mPARPi better than BRCAalt. Patients with HRDsig(+) status experienced favorable outcomes, even if they had BRCA-WT status. In contrast, patients with HRDsig(−) status did not show significant benefit from mPARPi treatment. HRDsig might predict benefit from mPARPi regardless of BRCAalt status.

Comparing Durvalumab, Olaparib, and Cediranib Monotherapy, Combination Therapy, or Chemotherapy in Patients with Platinum-Resistant Ovarian Cancer with Prior Bevacizumab: The Phase II NRG-GY023 Trial

Abstract Purpose: We assessed the efficacy of anti–PD-L1 durvalumab in combination with olaparib and cediranib (DOC), compared with the standard-of-care chemotherapy (SOC) in patients with platinum-resistant ovarian cancer (PROC), who had prior bevacizumab. Patients and Methods: NRG-GY023 was the first randomized four-arm superiority phase II trial enrolling patients with high-grade serous/endometrioid or clear-cell PROC with prior bevacizumab exposure. Patients were randomized 1:2:2:2 to SOC (weekly paclitaxel, topotecan, or pegylated liposomal doxorubicin), DOC, durvalumab + cediranib (DC), or olaparib + cediranib (OC). The primary endpoint was progression-free survival (PFS). The secondary endpoints included overall survival, overall response rate, and safety. The design had 80% power to detect an HR of 0.5 using a one-sided, α = 0.1-level test for each comparison with the SOC with a preplanned interim analysis. Experimental arms with HR estimates (vs. SOC) >0.87 could be discontinued. Results: A total of 153 patients were enrolled between April 4, 2021, and February 1, 2023. Accrual was permanently closed on February 1, 2023, due to futility. With a data cutoff of September 9, 2024, the median PFS was 3.4, 2.9, 2.5, and 2.8 months, and median overall survival was 7.5, 8.3, 5.7, and 10.2 months for SOC, DOC, DC, and OC, respectively. The overall response rate was 4.3% [95% confidence interval (CI), 0.00–0.19], 15.9% (95% CI, 0.07–0.29), 11.9% (95% CI, 0.05–0.24), and 9.1% (95% CI, 0.03–0.20) for SOC, DOC, DC, and OC, respectively. Compared with SOC, the PFS HR estimates were 1.003 (95% CI, 0.56–1.80), 1.108 (95% CI, 0.63–1.96), and 1.021 (95% CI, 0.57–1.82) for DOC, DC, and OC, respectively. No new safety signals were observed. Conclusions: In patients with PROC with prior bevacizumab, all experimental arms failed to reach the primary objective of improving PFS compared with SOC.

Resistance to Poly (ADP-Ribose) Polymerase Inhibitors (PARPi): Mechanisms and Potential to Reverse

This review will focus on the most common mechanisms for poly (ADP-ribose) polymerase inhibitors' (PARPi) resistance and the main strategies for overcoming acquired or de novo PARPi resistance. Initial approvals for PARPi as part of treatment for advanced epithelial ovarian cancer (EOC) started in 2014 with patient with recurrent cancer characterized by BRCA mutations in the 3rd and 4th line and now have approvals for front-line maintenance in both the BRCA mutated and BRCAwt populations. As with all therapies, patients will eventually develop resistance to treatment. The most common mechanisms for PARPi resistance include reversion mutations, methylation events, and restoration of homologous recombination deficiency (HRD) through combinations and targeting replication stress. As more and more patients receive initial treatment (and potential retreatment with PARPi), we need to better understand the mechanisms in which tumors acquire PARPi resistance.