Pembrolizumab

Pembrolizumab (Keytruda®) is a type of immunotherapy. It takes the “brakes” off of the immune system and activates tumor-killing immune cells. Pembrolizumab is FDA-approved for the treatment of all solid tumors, including prostate cancer, that have certain types or numbers of mutations. Specifically, these characteristics are: microsatellite instability-high (MSI-H), mismatch repair deficient (dMMR), or high tumor mutational burden (TMB-H).

Your doctor will order tests of your biopsies or tumor material from your prostate surgery. Studies suggest that approximately 3%–5% of patients with metastatic prostate cancer have the specific mutations in their tumor. Patients who qualify for this therapy must have progressed on prior treatment and have no satisfactory alternative treatment options.

Pembrolizumab is delivered intravenously once every 3 weeks. Because it works by modifying the immune system, there are rare but serious side effects related to overactive immune responses. These are typically treated by stopping the drug and, in some cases, starting steroids or other immune-suppressive medications.

Last Reviewed: 12/2023