Merck’s Keytruda Falls Short In Two Trials

Keytruda may be Merck’s blockbuster drug for cancer, but it is not omnipotent. The company, known as MSD outside of the US and Canada, is discontinuing a Phase 3 trial evaluating the anti-PD-1 therapy in prostate cancer, while the drug missed the primary endpoint in another Phase 3 for non-small cell lung cancer (NSCLC).   

“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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Keytruda Showed No Improvement in Survival Endpoints in Prostate Cancer

In an interim analysis of Keynote-641 assessing a combination therapy containing Keytruda in metastatic castration-resistant prostate cancer (mCRPC), Keytruda in combination with enzalutamide and androgen deprivation therapy (ADT) did not show an improvement in radiographic progression-free survival (rPFS) or overall survival (OS) when compared to placebo. 

As the trial crossed a prespecified futility boundary for OS, Merck has discontinued the trial at the recommendation of an independent data monitoring committee. The company has advised patients in the study to speak to their physician regarding treatment. 

Keytruda Survival Benefit Seen but Not Statistically Significant in NSCLC 

In the case of the Keynote-789 trial evaluating a Keytruda combination in patients with metastatic non-squamous NSCLC with epidermal growth factor receptor (EGFR) mutations (whose cancers progressed despite tyrosine kinase inhibitor (TKI) including osimertinib), the trial failed to meet the two key primary endpoints in survival. 

While Keytruda in combination with permetrexed plus platinum-based chemotherapy showed improvements in PFS and OS compared to chemotherapy alone, the results did not reach statistical significance. 

On the safety front, Keytruda’s profile was consistent with that observed in previous studies and no new safety signals were found. However, a higher incidence of Grade 3-5 adverse events and serious side effects was associated with the Keytruda combination in Keynote-641. The results will be shared at future scientific congresses, said Merck. 

Related posts:

Merck Presents Positive News For Keytruda Combination in NSCLC Yet Another Feather in Merck’s Crown, Keytruda Meets Endpoint in Phase 3 Trial for Triple Negative Breast Cancer Merck’s Keytruda Bags FDA Approval for Early Kidney Cancer in Adjuvant Setting Merck, Eisai’s Keytruda-Lenvima Combo Fails in Melanoma and Colorectal Cancer Trials

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Joy Lin

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