The PARP inhibitor olaparib has efficacy and meaningful long-term survival benefit in patients with germline BRCA-mutated, HER2-negative metastatic breast cancer, as shown by the OlympiAD extended follow-up study recently published on the European Journal of Cancer.
Adjuvant olaparib has already shown efficacy, with a significantly longer survival free of invasive or distant disease than placebo, among patients with high-risk, HER2-negative early breast cancer and germline BRCA1/2 mutations in the phase 3 OlympiA study; it also significantly prolonged progression-free survival versus chemotherapy treatment of physician’s choice in patients with germline BRCA-mutated, HER2-negative metastatic breast cancer, as shown in OlympiAD study. In this new extended follow-up OlympiAD study patients who had received ≤2 lines of chemotherapy for metastatic disease were randomized 2:1 to olaparib or chemotherapy treatment of physician’s choice; overall survival was then analyzed every 6 months. In the overall population of 302 patients, median overall survival was 19.3 months for olaparib and 17.1 months for chemotherapy and three-year survival was 27.9% versus 21.2% respectively; in first-line metastatic breast cancer, median overall survival was longer for olaparib than chemotherapy (22.6 vs 14.7 months) and three-year survival was 40.8% versus 12.8% respectively, with no new serious adverse events related to olaparib. «A subset (8.8%) of patients received treatment with olaparib for at least 3 years: these findings are consistent with evidence of prolonged responses to olaparib in the treatment of ovarian cancer», authors note. «The finding that 40.8% of olaparib-treated patients who had not previously received chemotherapy for metastatic breast cancer were alive at 3 years, compared with 12.8% in the chemotherapy-treated arm, raises the possibility of a meaningful overall survival benefit for some patients receiving olaparib in the first-line setting for metastatic breast cancer. These exploratory findings should be investigated in further studies, including those employing real-world data», authors conclude.