Färkkilä, Anniina

PURPOSE The multicenter, open-label, randomized phase 2 NCI-9944 study ( NCT02595892 ) demonstrated that addition of ATR inhibitor (ATRi) berzosertib to gemcitabine increased progression-free survival (PFS) compared to gemcitabine alone (hazard ratio [HR]=0.57, one-sided log-rank P = .044, which met the one-sided significance level of 0.1 used for sample size calculation). METHODS We report here the final overall survival (OS) analysis and biomarker correlations (ATM expression by immunohistochemistry, mutational signature 3 and a genomic biomarker of replication stress) along with post-hoc exploratory analyses to adjust for crossover from gemcitabine to gemcitabine/berzosertib. RESULTS At the data cutoff of January 27, 2023 (>30 months of additional follow-up from the primary analysis), median OS was 59.4 weeks with gemcitabine/berzosertib versus 43.0 weeks with gemcitabine alone (HR 0.79, 90% CI 0.52 to 1.2, one-sided log-rank P = .18). An OS benefit with addition of berzosertib to gemcitabine was suggested in patients stratified into the platinum-free interval ≤3 months (N = 26) subgroup (HR, 0.48, 90% CI 0.22 to 1.01, one-sided log-rank P =.04) and in patients with ATM-negative/low (N = 24) tumors (HR, 0.50, 90% CI 0.23 to 1.08, one-sided log-rank P = .06). CONCLUSION The results of this follow-up analysis continue to support the promise of combined gemcitabine/ATRi therapy in platinum resistant ovarian cancer, an active area of investigation with several ongoing clinical trials.

5512 Background: The multicenter, open-label, randomized phase 2 NCI-9944 study (NCT02595892) demonstrated that addition of ATR inhibitor (ATRi) berzosertib to gemcitabine increased progression-free survival (PFS) compared to gemcitabine alone (HR = 0.57, one-sided log-rank p = 0.044, which met the one-sided significance level of 0.1 used for sample size calculation). Final overall survival (OS) and corresponding biomarker analyses are reported here. Methods: Patients (pts) with platinum-resistant high-grade serous ovarian cancer and unlimited previous lines of cytotoxic therapy in the platinum-sensitive setting but no more than one line of cytotoxic therapy in the platinum-resistant setting, were randomized 1:1 to gemcitabine/berzosertib versus gemcitabine alone. Randomization was stratified based on platinum free interval (PFI), PFI≤3 months versus > 3 months. Crossover from gemcitabine to gemcitabine/berzosertib was allowed upon disease progression by RECIST 1.1. OS was a secondary endpoint while preplanned exploratory correlative studies included assessment of DNA repair pathways and replication stress (RS) alterations by targeted gene sequencing and/or immunohistochemistry (IHC). Results: Seventy pts were randomly assigned to treatment with gemcitabine/berzosertib (34 pts) or gemcitabine alone (36 pts); 15 pts crossed over from gemcitabine to gemcitabine/berzosertib. At the final OS analysis (92.9% maturity), median follow-up was 53.2 weeks in the gemcitabine/berzosertib and 43 weeks in the gemcitabine alone groups. Median OS in the intent-to-treat (ITT) population was 59.4 weeks in the gemcitabine/berzosertib group versus 43.0 weeks in the gemcitabine alone group (HR 0.79, 90% CI 0.52-1.2, one-sided p = 0.18). However, when patients who crossed over to gemcitabine/berzosertib were excluded from analysis, a significant OS benefit was observed with gemcitabine/berzosertib (HR 0.60, 90%CI 0.37−0.97); HR was 0.26 (90% CI 0.1−0.7) in pts with PFI≤3 months and 0.89 (90%CI 0.50−1.59) in pts with PFI > 3 months. Furthermore, significant OS benefit was observed in pts with RS-low tumors (HR 0.39, 90%CI 0.17−0.91, defined as tumors harboring no genomic RS alterations related to loss of RB pathway regulation and/or oncogene-induced RS) but not in pts with RS-high tumors (HR 0.74, 90%CI 0.35−1.56). Additional targeted gene sequencing and IHC analyses as well as analyses adjusting for patient crossover will be reported at the meeting. Conclusions: In the ITT population, gemcitabine/berzosertib did not significantly improve OS versus gemcitabine alone. Pts with PFI≤3 months and pts with RS-low tumors may derive a survival advantage from addition of berzosertib to gemcitabine in the platinum-resistant setting. Clinical trial information: NCT02595892 .

Abstract Background: PARP inhibitor (PARPi) monotherapy has previously demonstrated clinical activity only in patients with a germline BRCA mutation (BRCAmut), while single-agent anti-programmed cell death protein 1 (PD-1) therapy has achieved response rates of only 5–20% in advanced triple negative breast cancer (TNBC). In preclinical studies, PARP inhibition enhanced anti-tumor immunity, increased infiltration of proliferating CD8+ T cells, and synergized with anti-PD-1 agents in BRCA wildtype (wt) tumors. TOPACIO is a fully enrolled, phase I/II trial of niraparib + pembrolizumab (pembro) in advanced TNBC. This combination achieved 28% objective response rate (ORR) and 50% disease control rate (DCR) in evaluable patients. Although activity was highest in patients with BRCAmut (ORR=60%; DCR=80%), durable clinical benefit was also observed in patients without BRCA mutations. In this study, we conducted exploratory biomarker analyses to evaluate their potential correlation with durable clinical benefit (any complete response [CR] or partial response [PR] regardless of duration or stable disease [SD] for ≥16 weeks) beyond BRCA mutations. Method: ORR was assessed by RECIST v1.1. Duration of disease control (DDC) was defined as time from first dose of study treatment to radiologic disease progression or death. Tumor mutational status of homologous recombination repair (HRR) and other DNA damage repair (DDR) pathway genes was determined using an NGS panel. Immunoprofiling was conducted using NanoString IO360 panel complimented with 30 DNA repair spike-ins. Tumor immune micro-environment was characterized using multiplex immuno-fluorescence (CycIF). PD-L1 status was determined using the Agilent/DAKO 22C3 IHC clinical trial assay. Results: Of 46 evaluable patients, 20 achieved durable clinical benefit (any CR/PR or SD≥16 weeks) with niraparib + pembro combination, of which 8 were tumor BRCA wild type (wt), and 1 was BRCA unknown. Of the 9 BRCAwt/unknown patients, 5 had deleterious mutations in HRR/DDR pathway genes, whereas the remaining 4 had no mutations (HRR/DDR wt). Mutations that were associated with response include CHEK1 (CR; DDC=10.3 mos), ATR (CR; DDC=6.4 mos), PALB2 (PR; DDC=3.5 mos), BLM (SD; DDC=8.1 mos), and NBN/RAD51C (SD; DDC=3.7 mos). Of 4 patients that had no identified mutations (HRR/DDR wt), 1 patient had CR; DDC=10.3 mos, and the remaining 3 patients had SD with DDC ranging from ∼4-8 mos. Of note, all 4 HRR/DDR wt patients were also PD-L1-negative. Table:Durable clinical benefit in BRCAwt/unknown patientsHRR/DRR MutationsPD-L1 StatusBest ResponseDDC (Months)CHEK1+CR10.3†ATR+CR6.4PALB2*UnknownPR3.5BLM-SD8.1NBN/RAD51C+SD3.7None-CR10.3†None-SD8.2None-SD4.2None-SD3.9*BRCA status unknown; †Treatment is ongoing. Conclusion: Patients with mutations beyond BRCA achieved durable clinical benefit with niraparib + pembro treatment; five of these patients had DDC >6 mos. Mutations in genes that are associated with the HRR/DDR pathway appear to confer sensitivity to niraparib + anti-PD1. Additional translational analyses, including immunoprofiling and CycIF, will be presented. Funding: TESARO, Inc., Waltham, MA, USA sponsored the study. Citation Format: Vinayak S, Tolaney SM, Schwartzberg L, Mita M, McCann G, Tan AR, Wahner Hendrickson A, Forero A, Anders C, Wulf G, Dillon P, Lynce F, Zarwan C, Erban J, Färkkilä A, Zhou Y, Buerstatte N, Graham JR, Arora S, Dezube B, Telli ML. Durability of clinical benefit with niraparib + pembrolizumab in patients with advanced triple-negative breast cancer beyond BRCA: (TOPACIO/Keynote-162) [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr PD5-02.