Phase II trial of celecoxib in prostate-specific antigen recurrent prostate cancer after definitive radiation therapy or radical prostatectomy

Objectives: Recent evidence has shown that cyclooxygenase-2 (COX-2) inhibitors have potent antitumor activity in prostate cancer both in vitro and in vivo. However, human trials are absent. This study evaluated the efficacy of the COX-2 inhibitor celecoxib in prostate-specific antigen (PSA) recurrent prostate cancer after radiation therapy (X-ray therapy or XRT) or radical prostatectomy. Methods: Forty patients who had biochemical relapse after XRT or radical prostatectomy were treated with celecoxib 400 mg twice per day. Follow-up PSA levels were obtained at 3, 6,12, and 18 months and subsequently every 6 months thereafter. Data were evaluated by calculating PSA doubling times and by calculating the slope of the curve of log (PSA) versus time to assess rate of PSA increase before and after celecoxib treatment for each patient. Results: Thirty-six of 40 (90%) patients had a slowing effect on their rate of PSA after 3 months, including 11 of 40 with a decline and 8 of 40 with stabilization of PSA. Short-term responses at 3 months continued at 6, 12, 18 months Comparison of rate of PSA increase before versus after celecoxib treatment showed significant flattening of slope of log(PSA) versus time from pretreatment for each of the time points. There was no significant change in testosterone levels, suggesting an androgen-independent mechanism. Conclusions: COX-2 inhibitors may have an effect on serum PSA levels in patients with biochemical progression after XRT or radical prostatectomy. These results suggest that COX-2 inhibitors may help delay or prevent disease progression in these patients and thereby help extend the time until androgen deprivation therapy.