Merck unveils positive phase 3 results for Keytruda in early breast cancer

Merck & Co, known as MSD outside the US and Canada, announced encouraging overall survival (OS) results from its phase 3 KEYNOTE-522 trial for Keytruda (pembrolizumab) in early-stage breast cancer. The KEYNOTE-522 study assessed Keytruda, combined with chemotherapy as a pre-surgery neoadjuvant treatment, followed by Keytruda alone as a post-surgery adjuvant treatment in patients with high-risk early-stage triple-negative breast cancer (TNBC).

At the European Society for Medical Oncology Congress and in the New England Journal of Medicine, data showed that the Keytruda regimen lowered 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 those receiving Keytruda, versus 81.7% for the chemotherapy/placebo group, with median OS not reached in either cohort.

These findings were consistent across various subgroups defined by tumor size and PD-L1 expression. The safety profile of Keytruda aligned with previous studies' observations. TNBC, a particularly aggressive breast cancer form, represents up to 15% of the roughly 56,800 annual breast cancer diagnoses in the UK.

Keytruda enhances the immune system’s capacity to identify and combat tumor cells and is already approved for treating certain breast cancer cases, including high-risk early-stage TNBC. Gursel Aktan, vice president of global clinical development at Merck Research Laboratories, noted 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” for this patient group.

Keytruda’s approvals extend beyond breast cancer, including treatments for cervical cancer, bladder cancer, biliary tract cancer, non-small cell lung cancer, and renal cell carcinoma. Currently, over 1,600 trials are investigating Keytruda, including studies on its combination with Merck and Moderna’s investigational skin cancer vaccine.