Salvage Therapy With Oral Metronomic Cyclophosphamide and Methotrexate for Castration refractory Metastatic Adenocarcinoma of the Prostate Resistant to Docetaxel

OBJECTIVE To investigate the activity and toxicity of metronomic chemotherapy with low-dose oral cyclophosphamide (CTX) and methotrexate (MTX) in patients with metastatic CRPC that progresses after docetaxel. Patients with castration-resistant prostate cancer (CRPC) that progresses after docetaxel may benefit from receiving further chemotherapy. METHODS Patients were treated with CTX 50 mg/d p.o. plus MTX 2.4 mg p.o. twice per week without rest periods. All patients received simultaneous luteinizing hormone-releasing hormone analogue. Prostate-specific antigen (PSA) response was defined as a 50% reduction on 2 evaluations at least 4 weeks apart. Objective response was measured according to the RECIST criteria. Pain relief was analyzed with the McGill-Melzack Pain Questionnaire. Simon’s 2-stage design for phase II study was used. Time to progression and progression-free and overall survival were computed. Toxicity was recorded according to the CTC-NCCN criteria. RESULTS A PSA decrease 50% was recorded in 15 of 58 evaluable patients (25%), and objective partial response in 3 (18%) and stable disease in 4 (24%) of 17 patients with measurable disease. Disease in 10 patients (59%) progressed. Pain intensity decreased in 16 (30%), increased in 18 (33%), and remained stable in 18 (33%) patients. Five patients discontinued narcotic analgesics for a mean duration of 12 weeks. Transitory grade 3 leukopenia was observed in 4 cases (7%), grade 3 thrombocytopenia in 2 (3%), and grade 2 anemia in 4 (7%). CONCLUSION This study demonstrates the feasibility, activity, and tolerability of oral low-dose CTX and MTX given on a metronomic schedule in patients with CRPC progressing after docetaxel-based chemotherapy.