Prostate cancer is a type of cancer that develops in the prostate gland, which is a small walnut-shaped gland in men that produces the seminal fluid that nourishes and transports sperm. It is the second most common cancer in men worldwide, and it is estimated that over 248,000 new cases of prostate cancer were diagnosed in the United States in 2021 alone.
The risk of developing prostate cancer increases with age, and it is more common in African American men and those with a family history of the disease. Early detection and treatment of prostate cancer are crucial for a better prognosis, and regular screening tests such as a digital rectal exam and prostate-specific antigen (PSA) test are recommended for men at risk.
A clinical trial has shown that the PD-L1 inhibitor avelumab, in combination with stereotactic ablative body radiotherapy (SABR), may be a promising treatment option for men with metastatic castration-resistant prostate cancer (mCRPC) who have progressed after at least one prior androgen receptor-directed therapy. The trial enrolled 31 men with a median age of 71 years.
The primary objective of the study was to evaluate the efficacy and safety of the combination therapy in mCRPC patients. The patients were administered avelumab 10mg/kg intravenously every two weeks for 24 weeks (12 cycles) along with a single fraction of SABR (20 Gy) within five days before the first and second avelumab treatments.
The primary endpoint of the study was the disease control rate (DCR), which was defined as a confirmed complete or partial response of any duration or stable disease/non-complete response/non-progressive disease for ≥6 months. The secondary endpoints were the objective response rate (ORR), radiographic progression-free survival, overall survival, and safety.
The study found that 15 out of 31 patients (48%) had a disease control rate (DCR) of complete or partial response or stable disease for at least 6 months. Out of 16 patients, 5 (31%) had an objective response rate (ORR). Among patients who did not receive radiation therapy, 4 out of 12 (33%) had an ORR. The median radiographic progression-free survival was 8.4 months, and the median overall survival was 14.1 months. The study also found that changes in plasma androgen receptor levels were linked to a lower DCR (22% vs. 71%).
The study's findings suggest that the combination therapy of avelumab with SABR is a promising treatment option for men with mCRPC who have progressed after at least one prior androgen receptor-directed therapy. The study also found that the therapy was well-tolerated, with only 16% of patients experiencing grade 3-4 treatment-related adverse events, and only 10% requiring high-dose corticosteroid therapy.
The results of this clinical trial demonstrate that avelumab with SABR is a promising treatment option for men with mCRPC who have progressed after at least one prior androgen receptor-directed therapy. The combination therapy demonstrated encouraging activity and acceptable toxicity and warrants further investigation.