Phase 2 trial of weekly intravenous 1,25 dihydroxy cholecalciferol (calcitriol) in combination with dexamethasone for castration-resistant prostate cancer.

BACKGROUND: Preclinical data indicate that there is substantial antitumor activity and synergy between calcitriol and dexamethasone. On the basis of these data, the authors conducted a phase 2 trial of intravenous (iv) calcitriol at a dose of 74 microg weekly (based on a recent phase 1 trial) and dexamethasone in patients with castration-resistant prostate cancer (CRPC). METHODS: A 2-stage Kepner-Chang design was used. Oral dexamethasone at a dose of 4 mg was given weekly on Days 1 and 2, and iv calcitriol (74 microg over 1 hour) was administered weekly on Day 2 from 4 to 8 hours after the dexamethasone dose in patients with CRPC. Laboratory data were monitored weekly, and renal sonograms, computed tomography scans, and bone scans were obtained every 3 months. Disease response was assessed by using the Response Evaluation Criteria in Solid Tumors (RECIST) and standard criteria for prostate-specific antigen (PSA) response. The calcitriol dose was delineated by from the authors' recent phase 1 trial. RESULTS: Of 18 evaluable patients, 15 patients were Caucasian (83%). No patients had a complete or partial response by either RECIST or PSA response criteria. Fourteen patients had progressive disease, 2 patients refused to continue treatment (after 64 days and 266 days), and 2 patients remain on the trial (for 306 days and 412 days).The median time to disease progression was 106 days (95% confidence interval, 80-182 days). Fourteen episodes of grade 3 or 4 toxicity were noted in 7 patients (hyperglycemia, hypocalemia, chest pain, dyspnea, hypercalcemia, hypophosphatemia, cardiac arrhythmia, and pain). Only 1 episode of grade 3/ 4 toxicity was related definitely to calcitriol (hypercalcemia). No treatment-related deaths were noted. CONCLUSIONS: High-dose, iv calcitriol at a dose of 74 microg weekly in combination with dexamethasone was well tolerated but failed to produce a clinical or PSA response in men with CRPC.

Phase II study of fulvestrant (Faslodex) in castration resistant prostate cancer.

BACKGROUND: Preclinical evidence supports the role of estrogen receptor signaling in prostate cancer. In this trial we investigated the tolerability and efficacy of fulvestrant, a pure estrogen receptor antagonist, in the treatment of castration resistant prostate cancer (CRPC). METHODS: Patients with CRPC were enrolled after written informed consent. Fulvestrant was administered by intramuscular injection at a dose of 500 mg on day 0, then 250 mg on day 14, day 28 and monthly thereafter. History, physical examination, serum prostate specific antigen (PSA) levels and toxicity was evaluated monthly. Radiographic studies were repeated every 3 months to assess disease. Treatment was continued until disease progression, unacceptable toxicity, non-compliance or consent withdrawal. RESULTS: Twenty patients were enrolled over a period of six months. All patients were Caucasians with median age of 69.5 years [range: 47-85 years]. Sixteen patients (80%) had radiological evidence of metastasis and four patients (20%) had rising PSA as the only evidence of progressive disease. Patients received a median of three treatment cycles of fulvestrant [range: 1-11]. Median time to progression was 4.3 months (95% confidence interval of 3-5.7 months) and median overall survival was 19.4 months (range: 9.9-19.4 months) after a median follow-up of 16 months. No patient showed >or=50% reduction in PSA or radiologic improvement. Few adverse events were noted, none of which were attributed directly to fulvestrant. CONCLUSION: Fulvestrant was well tolerated but failed to produce clinical or PSA response in men with CRPC.