Merck & Co – known as MSD outside the US and Canada – has shared positive overall survival (OS) results from a late-stage study of its Keytruda (pembrolizumab) regimen in early-stage breast cancer.
The phase 3 KEYNOTE-522 trial has been evaluating Keytruda in combination with chemotherapy as a neoadjuvant treatment before surgery, followed by the anti-PD-1 therapy as a single agent adjuvant treatment after surgery, in patients with high-risk early-stage triple-negative breast cancer (TNBC).
Results presented at this year’s European Society for Medical Oncology Congress and simultaneously published in the New England Journal of Medicine demonstrated that the Keytruda regimen reduced the risk of death by 34% compared to a chemotherapy/placebo regimen after a median follow-up of 75.1 months.
The five-year OS rate was 86.6% for patients randomised to receive the Keytruda regimen versus 81.7% for those in the chemotherapy/placebo cohort, with median OS not reached in either group.
Merck added that exploratory analyses showed that the OS benefit of the Keytruda regimen was consistent across pre-specified subgroups, including those defined by tumour size and PD-L1 expression, and the safety profile of the drug was consistent with that observed in previous studies.
Approximately 56,800 people are diagnosed with breast cancer in the UK every year and TNBC, the most aggressive form of the disease, accounts for up to 15% of all cases.
Keytruda works by increasing the ability of the body’s immune system to help detect and fight tumour cells, and is already authorised to treat certain cases of breast cancer, including high-risk early-stage TNBC.
Gursel Aktan, vice president, global clinical development, Merck Research Laboratories, outlined that Keytruda is now the “first and only immunotherapy-based regimen to show a statistically significant and clinically meaningful improvement in OS compared to chemotherapy alone” in this patient population.
Beyond breast cancer, Keytruda holds approvals to treat a wide range of cancers, including specific cases of cervical cancer, bladder cancer, biliary tract cancer, non-small cell lung cancer and renal cell carcinoma.
There are also currently more than 1,600 trials studying the therapy, including one evaluating it in combination with Merck and Moderna’s investigational skin cancer vaccine.