Keytruda Misses Outcomes in Two Clinical Trials

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One of the trials investigating Keytruda has been discontinued because the drug did not significantly improve outcomes in patients with prostate cancer.

Two clinical trials evaluating Keytruda (pembrolizumab) in different tumor types have failed to meet their main goals, and one of the trials is being discontinued according to a press release from Merck, the manufacturer of the immunotherapy agent.

The first was the phase 3 KEYNOTE-641 clinical trial evaluating Keytruda combined with Xtandi (enzalutamide) and androgen-deprivation therapy in patients with metastatic castration-resistant prostate cancer — which has since been discontinued.

At the interim analysis, the Keytruda combination did not improve radiographic progression-free survival (time during and after treatment when the patient lives without disease progression) or overall survival (time from diagnosis or treatment start when patients are alive) — the main goals of the trial — compared to a placebo combination.

Additionally, the phase 3 KEYNOTE-789 clinical trial, which evaluated Keytruda plus pemetrexed plus platinum-based chemotherapy, did not meet the primary endpoint of overall survival. The trial was investigating the combination in patients with metastatic nonsquamous non-small cell lung cancer with epidermal growth factor receptor (EGFR)-genomic tumor mutations, who have previously progressed on a tyrosine kinase inhibitor (TKI), including Tagrisso (osimertinib).

At the final analysis, there was an improvement in overall survival with the Keytruda combination, however it was not statistically significant. And a similar trend was observed with progression-free survival.

In both the KEYNOTE-641 and KEYNOTE-789 clinical trials, side effects from Keytruda were consistent of that which were previously reported. Of note, in KEYNOTE-641 the combination was associated with a greater risk of sever or worse side effects.

“Throughout the clinical development of Keytruda, we have asked the tough questions in an effort to fully explore the potential of this breakthrough immunotherapy and determine how we could help as many patients as possible,” said Dr. Eliav Barr, senior vice president and head of global clinical development, chief medical officer, Merck Research Laboratories. “Science is rarely a straight line, and while we are disappointed in these study results, our research to investigate Keytruda in many difficult-to-treat types of cancer continues in earnest. We are extremely grateful to all the investigators and patients for their participation in these studies.”

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