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Cancer. 2010 May 1;116(9):2132-9. doi: 10.1002/cncr.24973.

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

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Department of Medicine, Roswell Park Cancer Institute, Buffalo, New York 14263, USA.



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).


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.


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.


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.

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