Astellas and Pfizer announced positive topline results from the Phase 3 EMBARK trial, which evaluated the effectiveness of Xtandi (enzalutamide) in men with high-risk biochemical recurrence (BCR) non-metastatic hormone-sensitive prostate cancer (nmHSPC). Patients in the study were randomly assigned to one of three groups: Xtandi plus leuprolide, placebo plus leuprolide, or Xtandi alone.
The trial's primary endpoint was metastasis-free survival (MFS). There was significant MFS improvement in patients treated with Xtandi plus leuprolide compared to those who received placebo plus leuprolide.
While the secondary endpoint data were not yet mature at the time of analysis, there was a positive trend in the overall survival (OS), which will be further evaluated as patients in the trial are followed. In addition to meeting the primary endpoint, the study achieved a statistically significant and clinically meaningful improvement in MFS for patients treated with Xtandi alone versus placebo plus leuprolide.
Several other key secondary endpoints, including time to prostate-specific antigen (PSA) progression and time to first use of new antineoplastic therapy, also showed statistical significance, while other secondary endpoints are currently being analyzed.
Notably, no new safety concerns were observed during the preliminary safety analysis, which aligns with the established safety profile of Xtandi.
Merck has provided an update on KEYNOTE-641 Phase 3 clinical trial, evaluating the efficacy of Keytruda (pembrolizumab) in combination with enzalutamide and androgen deprivation therapy (ADT) in patients with metastatic castration-resistant prostate cancer (mCRPC).
Keytruda has not shown improvement in radiographic progression-free survival (rPFS) or overall survival (OS) versus placebo.
The safety profile was consistent with the existing safety profile of Keytruda.
Merck announced that it is stopping the Phase-3 KEYNOTE-991 trial, evaluating the combination of Keytruda (pembrolizumab), enzalutamide, and androgen deprivation therapy in patients with metastatic hormone-sensitive prostate cancer.
The recommendation was based on the independent Data Monitoring Committee, as the combination has not demonstrated improvement in overall survival (OS) or radiographic progression-free survival (rPFS).
The combination had a higher incidence of Grade 3-5 adverse events than the control arm. Merck announced it would inform the patients of the decision and suggest they speak to their physicians regarding treatment.