Merck and Co Inc (MRK)

[DewDiligence]

Keytruda fails again in prostate cancer—one of the few cancer indications where it has not seen a positive outcome:

https://www.businesswire.com/news/home/20230124006084/en/Merck-Announces-KEYNOTE-991-Trial-Evaluating-KEYTRUDA%C2%AE-pembrolizumab-Plus-Enzalutamide-and-Androgen-Deprivation-Therapy-in-Patients-With-Metastatic-Hormone-Sensitive-Prostate-Cancer-to-Stop-for-Futility

Merck…today announced that it will stop the Phase 3 KEYNOTE-991 trial investigating KEYTRUDA…in combination with enzalutamide and androgen deprivation therapy (ADT) for the treatment of patients with metastatic hormone-sensitive prostate cancer (mHSPC).

…At the interim analysis, KEYTRUDA in combination with enzalutamide [Xtandi] and ADT did not demonstrate an improvement in overall survival (OS) or radiographic progression-free survival (rPFS), the trial’s dual primary endpoints, compared to placebo plus enzalutamide and ADT.

This is Keytruda’s third recent phase-3 in prostate cancer. In the KEYNOTE-921 trial, which reported results in Aug 2021, Keytruda failed to show a statsig benefit when added to chemo in CRPC (#msg-169574792). In the KEYLINK-010 study, which reported results in Mar 2022, the combination of Keytruda and Lynparza (a PARP inhibitor) failed to show a statisig benefit compared to Xtandi or Zytiga in mCPRC refractory to chemo and either of Xtandi or Zytiga (https://www.clinicaltrials.gov/ct2/show/NCT03834519 ).

Keytruda is a great drug, but it’s not invincible.