Pembrolizumab in men with metastatic castrate-resistant prostate cancer

This study aimed to investigate the use of pembrolizumab (Keytruda) for prostate cancer (PCa). This study found that pembrolizumab was associated with a decline in prostate-specific antigen (PSA; a tumor marker for PCa). 

Pembrolizumab is a type of immunotherapy. It works by triggering your body’s immune system to fight the cancer cells. It belongs to a group of drugs called monoclonal antibodies. These drugs are sometimes called targeted therapies because they target specific proteins on the surface of cells. It has been approved for the treatment of several types of advanced cancer. However, its safety and effectiveness in patients with advanced prostate cancer (PCa) are still under investigation. 

This study included 48 men with advanced PCa who had at least 1 cycle of pembrolizumab. All men had been heavily treated before. Patients had progressive disease despite hormonal therapy (castrate-resistant). The PSA blood level was used to monitor how effective pembrolizumab was. 

17% (8/48) of the patients' PSA levels dropped by more than 50%. Another 9% of the patients had a PSA decline of more than 90%. The average progression-free survival was 1.8 months. 31% of patients stayed on pembrolizumab at 7.1 months. The duration of response ranged from 3.1 to 16.3 months.

This study found that pembrolizumab was associated with a decline in tumor marker for PCa in certain patients with advanced disease. 

This study included a very small number of participants. Also, the results were based on medical records. Some information might have been missing. Further studies are needed.