Cancer Treatment Today

The oral PARP inhibitor olaparib is approved for the treatment of patients with recurrent ovarian cancer and a BRCA mutation, and it has been shown to provide clinically meaningful benefit among such patients. Olaparib has also been shown to have promising activity in patients with metastatic breast cancer and a germline BRCA mutation. The OlympiAD trial was designed to compare the efficacy and safety of olaparib with the efficacy and safety of standard therapy with single-agent chemotherapy of the physician’s choice among patients with HER2-negative metastatic breast cancer and a germline BRCA mutation. This study was a randomized, open-label, phase 3 trial in which olaparib monotherapy was compared with standard therapy in patients with a germline BRCA mutation and human epidermal growth factor receptor type 2 (HER2)negative metastatic breast cancer who had received no more than two previous chemotherapy regimens for metastatic disease.

Among patients with HER2-negative metastatic breast cancer and a germline BRCA mutation, olaparib monotherapy provided a significant benefit over standard therapy; median progression-free survival was 2.8

“Background: The Belgian Precision initiative aims to maximize the implementation of tumor-agnostic next-generation sequencing in patients with advanced cancer and enhance access to molecularly guided treatment options. Academic tumor-agnostic basket phase II studies are part of this initiative. The current investigator-driven trial aimed to investigate the efficacy of olaparib in advanced cancers with a (likely) pathogenic mutation (germline or somatic) in a gene that plays a role in homologous recombination (HR).

Patients and methods: This open-label, multi-cohort, phase II study examines the efficacy of olaparib in patients with an HR gene mutation in their tumor and disease progression on standard of care. Patients with a somatic or germline mutation in the same gene define a cohort. For each cohort, a Simon minimax two-stage design was used. If a response was observed in the first 13 patients, 14 additional patients were included. Here, we report the results on four completed cohorts: patients with a BRCA1, BRCA2, CHEK2 or ATM mutation.

Results: The overall objective response rate across different tumor types was 11% in the BRCA1-mutated (n = 27) and 21% in the BRCA2-mutated (n = 27) cohorts. Partial responses were seen in pancreatic cancer, gallbladder cancer, endocrine carcinoma of the pancreas and parathyroid cancer. One patient with a BRCA2 germline-mutated colon cancer has an ongoing complete response with 19+ months on treatment. Median progression-free survival in responding patients was 14+ months (5-34+ months). The clinical benefit rate was 63% in the BRCA1-mutated and 46% in the BRCA2-mutated cohorts. No clinical activity was observed in the ATM (n = 13) and CHEK2 (n = 14) cohorts.

Conclusion: Olaparib showed efficacy in different cancer types harboring somatic or germline mutations in the BRCA1/2 genes but not in ATM and CHEK2. Patients with any cancer type harboring BRCA1/2 mutations should have access to olaparib.” (Joris, S., et al. 2023).

A small study by George, et al. “a subgroup analysis in those with somatic not germline BRCA mutations indicated a comparable benefit.”

“Background: Poly(adenosine diphosphate-ribose) polymerase inhibitors target cancers with defects in homologous recombination repair by synthetic lethality. New therapies are needed to reduce recurrence in patients with BRCA1 or BRCA2 germline mutation-associated early breast cancer.

Methods: We conducted a phase 3, double-blind, randomized trial involving patients with human epidermal growth factor receptor 2 (HER2)-negative early breast cancer with BRCA1 or BRCA2 germline pathogenic or likely pathogenic variants and high-risk clinicopathological factors who had received local treatment and neoadjuvant or adjuvant chemotherapy. Patients were randomly assigned (in a 1:1 ratio) to 1 year of oral olaparib or placebo. The primary end point was invasive disease-free survival.

Results: A total of 1836 patients underwent randomization. At a prespecified event-driven interim analysis with a median follow-up of 2.5 years, the 3-year invasive disease-free survival was 85.9% in the olaparib group and 77.1% in the placebo group (difference, 8.8 percentage points; 95% confidence interval [CI], 4.5 to 13.0; hazard ratio for invasive disease or death, 0.58; 99.5% CI, 0.41 to 0.82; P<0.001). The 3-year distant disease-free survival was 87.5% in the olaparib group and 80.4% in the placebo group (difference, 7.1 percentage points; 95% CI, 3.0 to 11.1; hazard ratio for distant disease or death, 0.57; 99.5% CI, 0.39 to 0.83; P<0.001). Olaparib was associated with fewer deaths than placebo (59 and 86, respectively) (hazard ratio, 0.68; 99% CI, 0.44 to 1.05; P = 0.02); however, the between-group difference was not significant at an interim-analysis boundary of a P value of less than 0.01. Safety data were consistent with known side effects of olaparib, with no excess serious adverse events or adverse events of special interest.

Conclusions: Among patients with high-risk, HER2-negative early breast cancer and germline BRCA1 or BRCA2 pathogenic or likely pathogenic variants, adjuvant olaparib after completion of local treatment and neoadjuvant or adjuvant chemotherapy was associated with significantly longer survival free of invasive or distant disease than was placebo. Olaparib had limited effects on global patient-reported quality of life.” (Tutt, A. N. J., et al. 2021).

“In the primary analysis of the phase III OlympiAD trial, olaparib significantly prolonged progression-free survival (PFS) vs chemotherapy treatment of physician’s choice (TPC) in patients with germline BRCA-mutated (gBRCAm), HER2-negative metastatic breast cancer (mBC). We report subgroup analyses for the final analysis at a median OS follow-up of 18.9 months (olaparib) and 15.5 months (TPC). Patients (N = 302) with gBRCAm, HER2-negative mBC and <=2 previous lines of chemotherapy for mBC were randomized 2:1 to open-label olaparib (300 mg twice daily) or TPC. All subgroup analyses were prespecified except site of metastases. Investigator-assessed median PFS was 8.0 months (95% confidence interval [CI] 5.8-8.4; 176/205 events) for olaparib and 3.8 months (95% CI 2.8-4.2; 83/97 events) for TPC (hazard ratio 0.51, 95% CI 0.39-0.66). In subgroup analyses, median PFS hazard ratios (95% CI) favored olaparib: hormone receptor status (triple-negative: 0.47, 0.32-0.69; hormone receptor-positive: 0.52, 0.36-0.75); gBRCAm (BRCA1: 0.49, 0.35-0.71; BRCA2: 0.49, 0.33-0.74); site of metastases (visceral/CNS: 0.53, 0.40-0.71; non-visceral: 0.45, 0.23-0.98); prior chemotherapy for mBC (yes: 0.51, 0.38-0.70; no: 0.49, 0.30-0.82); prior platinum-based chemotherapy for BC (yes: 0.49, 0.30-0.83; no: 0.50, 0.37-0.69); progressive disease at randomization (yes: 0.48, 0.35-0.65; no: 0.61, 0.36-1.07). Investigator-assessed objective response rates were higher across all subgroups with olaparib (35-68%) vs TPC (5-40%). Global health status/health-related quality of life increased in all subgroups with olaparib vs decreased/no change with TPC. These data confirm the consistency of olaparib benefit across patient subgroups in OlympiAD.” (Senkus, E., et al. 2023).
George, A., Banerjee, S., & Kaye, S. (2017). Olaparib and somatic BRCA mutations. Oncotarget, 8(27), 43598–43599. https://doi.org/10.18632/oncotarget.18419

Joris, S., Denys, H., Collignon, J., Rasschaert, M., T’Kint de Roodenbeke, D., Duhoux, F. P., Canon, J. L., Tejpar, S., Mebis, J., Decoster, L., Aftimos, P., & De Grève, J. (2023). Efficacy of olaparib in advanced cancers with germline or somatic mutations in BRCA1, BRCA2, CHEK2 and ATM, a Belgian Precision tumor-agnostic phase II study. ESMO open, 8(6), 102041. https://doi.org/10.1016/j.esmoop.2023.102041

Senkus, E., Delaloge, S., Domchek, S. M., Conte, P., Im, S. A., Xu, B., Armstrong, A., Masuda, N., Fielding, A., Robson, M., & Tung, N. (2023). Olaparib efficacy in patients with germline BRCA-mutated, HER2-negative metastatic breast cancer: Subgroup analyses from the phase III OlympiAD trial. International journal of cancer, 153(4), 803–814. https://doi.org/10.1002/ijc.34525

Tutt, A. N. J., Garber, J. E., Kaufman, B., Viale, G., Fumagalli, D., Rastogi, P., Gelber, R. D., de Azambuja, E., Fielding, A., Balmaña, J., Domchek, S. M., Gelmon, K. A., Hollingsworth, S. J., Korde, L. A., Linderholm, B., Bandos, H., Senkus, E., Suga, J. M., Shao, Z., Pippas, A. W., OlympiA Clinical Trial Steering Committee and Investigators (2021). Adjuvant Olaparib for Patients with BRCA1- or BRCA2-Mutated Breast Cancer. The New England journal of medicine, 384(25), 2394–2405. https://doi.org/10.1056/NEJMoa2105215