A phase I study of the vitamin D 3 analogue ILX23-7553 administered orally to Patients with advanced solid tumors

Rajul K. Jain, Donald L. Trump, Merrill J. Egorin, Manuel Fernandez, Candace S. Johnson, Ramesh K. Ramanathan

Research output: Contribution to journalArticlepeer-review

13 Scopus citations


Purpose: ILX23-7553 (1,25-dihydroxy-16-ene-23-yne vitamin D3) is a vitamin D analogue that was developed to avoid the hypercalcemia that may limit the use of vitamin D as an anti-cancer agent. We performed a phase I study of ILX23-7553 to determine its side-effect profile, pharmacokinetics, and to document any observed antitumor activity. Patients and Methods: Adult patients with refractory solid tumors were enrolled. A modified Fibonacci dose escalation scheme was employed. ILX23-7553 was administered orally daily for three consecutive days, and repeated in 7-day cycles. Plasma drug concentrations were assayed by radioimmunoassay and radioreceptor assay. Results: Sixteen patients were enrolled to 10 dose levels ranging from 1.7 to 37.3 μg/m 2/day. The maximum tested dose was six times higher than the maximally-tolerated dose (MTD) in dogs. Dose-limiting toxicity was not observed. ILX23-7553 concentrations on cycle 1 day 1 of treatment were comparable to concentrations on cycle 2 day 1, suggesting limited accumulation. One patient with adrenal cortical cancer had stable disease for 23 weeks, but no objective responses were observed. Conclusions: ILX23-7553 was well tolerated at the doses tested, with no evidence of hypercalcemia. The plasma concentrations achieved were approximately 100-fold lower than those associated with tumor growth inhibition in vitro, limiting use of this formulation.

Original languageEnglish (US)
Pages (from-to)1420-1425
Number of pages6
JournalInvestigational New Drugs
Issue number6
StatePublished - Dec 2011


  • Calcitriol
  • Cancer
  • Oncology
  • Phase I
  • Vitamin D

ASJC Scopus subject areas

  • Oncology
  • Pharmacology
  • Pharmacology (medical)


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