Phase 2 Trial of Weekly Intravenous 1,25 Dihydroxy Cholecalciferol (Calcitriol) in Combination With Dexamethasone for Castration-Resistant Prostate Cancer

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

Abstract

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.

Publication types

  • Clinical Trial, Phase II

MeSH terms

  • Administration, Oral
  • Aged
  • Aged, 80 and over
  • Antineoplastic Combined Chemotherapy Protocols / adverse effects
  • Antineoplastic Combined Chemotherapy Protocols / therapeutic use*
  • Calcitriol / administration & dosage*
  • Calcium / blood
  • Creatinine / blood
  • Dexamethasone / administration & dosage*
  • Drug Administration Schedule
  • Humans
  • Injections, Intravenous
  • Male
  • Middle Aged
  • Prostate-Specific Antigen / blood
  • Prostatic Neoplasms / drug therapy*
  • Retreatment

Substances

  • Dexamethasone
  • Creatinine
  • Prostate-Specific Antigen
  • Calcitriol
  • Calcium