Lenalidomide monotherapy in chemotherapy-naive, castration-resistant prostate cancer patients: final results of a phase II study.

BACKGROUND: We investigated the activity of lenalidomide, which has antiangiogenic, antineoplastic, and immunomodulatory properties, in chemotherapy-naive, castration-resistant prostate cancer (CRPC) patients.

PATIENTS: Patients received 25 mg/d lenalidomide for 21 days in 28-day cycles, until disease progression or unacceptable toxicity developed. Endpoints included overall response rate and clinical benefit (overall response + stable disease), toxicity, time to radiographic progression, and time to prostate-specific antigen (PSA) progression, overall survival, and quality of life.

RESULTS: Thirty-two patients were enrolled in the study; of these, 77% (n = 25) had Gleason scores ≥ 7. The median age was 74 years (58-89 y), the median PSA level was 66 ng/mL (2-919 ng/mL), and 5 of 32 patients (17%) had liver or lung involvement. The median number of lenalidomide cycles was 3 (1-16 cycles). Stable disease was seen in 20 patients, for a clinical benefit rate of 63%. The median time to radiographic progression was 4 months (2-16 mo); the median overall survival was 20 months. Of 27 PSA-evaluable patients, 13 (48%) had a decline in PSA level; 3 (11%) had > 50% PSA decrease; the median time to PSA progression was 3 months (2-9 mo). Grade 3/4 hematologic toxicities were the most common adverse events without adverse impact on quality of life. Serious adverse events occurred in 14 patients (44%), including 1 patient (3%) with a rash definitely related to lenalidomide.

CONCLUSION: Lenalidomide monotherapy demonstrates modest activity in chemotherapy-naive CRPC.