AstraZeneca and Merck (NYSE: MRK), known as MSD outside of the United States and Canada, announced long-term results from the OlympiA Phase 3 trial which showed LYNPARZA (olaparib) demonstrated sustained, clinically meaningful improvements in overall survival (OS), invasive disease-free survival (IDFS) and distant disease-free survival (DDFS) for people with germline BRCA-mutated (gBRCAm) HER2-negative high-risk early breast cancer.

These results were presented today at the 2024 San Antonio Breast Cancer Symposium (#GS1-09) and were consistent with positive primary results published in The New England Journal of Medicine .

Judy E. Garber, Chief of the Division of Cancer Genetics and Prevention at Dana-Farber Cancer Institute and co-principal investigator of the trial said, “These exciting long-term data from OlympiA confirm that adjuvant treatment with olaparib for one year continues to deliver clinically meaningful survival benefit for patients with germline BRCA-mutated high-risk HER2-negative early breast cancer even after six years, with benefit persisting in all subgroups and with toxicity and pregnancy data reassuring for this generally younger group. These data reinforce the importance of germline BRCA testing at the time of diagnosis, so we can identify all eligible patients who may benefit from treatment with olaparib as early as possible.”

Breast cancer is the second most diagnosed cancer worldwide, with an estimated 2.3 million patients diagnosed in 2022. About 63% of all breast cancer patients are diagnosed at an early stage of disease and BRCA mutations are found in approximately 5-10% of patients.

Susan Galbraith, Executive Vice President, Oncology R&D, AstraZeneca, said: “Two years ago, LYNPARZA became the first and only PARP inhibitor to demonstrate a survival benefit in germline BRCA - mutated, HER2-negative and high-risk early-stage breast cancer. To see this benefit continue after six years of follow-up is tremendous for patients and reinforces how LYNPARZA is continuing to transform the treatment of BRCA - mutated early-stage breast cancer.”

Dr. Eliav Barr, senior vice president, head of global clinical development and chief medical officer, Merck Research Laboratories, said: “The durable long-term efficacy seen in the OlympiA study reinforces LYNPARZA as an important treatment option for those living with this truly challenging, very aggressive form of breast cancer.”

At a median follow-up of 6.1 years (maximum 9.6 years) in eligible patients, who had completed local treatment and standard neoadjuvant or adjuvant chemotherapy, LYNPARZA reduced the risk of death by 28% (hazard ratio [HR] 0.72; 95% confidence interval [CI] 0.56-0.93) versus placebo. In addition, 87.5% of patients treated with LYNPARZA remained alive versus 83.2% of those on placebo.

LYNPARZA also demonstrated sustained and clinically meaningful improvements in the primary and secondary endpoints of IDFS and DDFS. LYNPARZA reduced the risk of invasive breast cancer recurrence, second cancers or death by 35% (HR 0.65; 95% CI; 0.53-0.78) and reduced the risk of distant disease recurrence or death by 35% (HR 0.65; 95% CI; 0.53-0.81) versus placebo. The benefit with LYNPARZA was consistent across all key subgroups, including patients with high-risk, hormone-receptor-positive disease.