Keytruda Fails to Improve Overall Survival of Patients with Triple-Negative Breast Cancer, Phase 3 Trial Shows

Keytruda (pembrolizumab), Merck‘s anti-PD-1 checkpoint blockade immunotherapy, failed to prolong the overall survival of patients with metastatic triple-negative breast cancer (TNBC) beyond that provided by chemotherapy agents, a Phase 3 trial shows.

Checkpoint blockade immunotherapies are based on the principle of removing the “brakes” of our immune system and using its power to fight cancer faster and more effectively.

Keytruda works by targeting and inhibiting the activity of PD-1, a receptor found on the surface of immune T-cells, so that cancer cells are not able to evade being targeted and destroyed by T-cells.

After being approved by the U.S. Food and Drug Administration for the treatment of melanoma, non-small cell lung cancer, head and neck squamous cell carcinoma, classical Hodgkin lymphoma (cHL), and bladder cancer, Keytruda is now being tested for other indications, including breast cancer.

According to the latest updates provided by Merck, when administered alone as a second- or third-line treatment, Keytruda failed to improve the overall survival of women with metastatic TNBC, compared with conventional chemotherapy. This was the primary objective of a randomized, open-label Phase 3 trial (NCT02555657) called KEYNOTE-119.

The study was designed to assess the safety and efficacy of Keytruda administered intravenously (into the vein), at a dose of 200 mg every three weeks for up to two years, compared with single chemotherapy agents — Xeloda (capecitabine), Halaven (eribulin), Gemzar (gemcitabine), or Navelbine (vinorelbine) — in patients with advanced TNBC.

Other trial objectives, including patients’ progression-free survival (the time patients lived without their disease worsening), overall response rate, disease control rate, and duration of response, were not formally assessed, because the primary goal was not reached.

Keytruda’s safety profile in the trial was consistent with what had been reported in previous studies. No new safety concerns were found over the course of the study. Merck is planning to present the findings of KEYNOTE-119 in an upcoming meeting.

“Metastatic triple-negative breast cancer is an aggressive and challenging disease to treat, especially after progression on initial standard-of-care treatment,” Roy Baynes, senior vice president and head of global clinical development, chief medical officer of Merck Research Laboratories, said in a press release.

“While we are disappointed by the outcome of this monotherapy trial, we are continuing to study Keytruda in earlier stages of the disease and in combination with chemotherapy to address the unmet medical need of patients with triple negative breast cancer. We are grateful to the patients and investigators for their participation in this important study,” he added.

Other Phase 3 trials, including KEYNOTE-355 (NCT02819518) and KEYNOTE-522 (NCT03036488), examining the therapeutic potential of Keytruda in combination with chemotherapy agents for TNBC, are currently underway.