Oral administration of gemcitabine in patients with refractory tumors: a clinical and pharmacologic study

Clin Cancer Res. 2008 Jun 1;14(11):3477-86. doi: 10.1158/1078-0432.CCR-07-4521.


Purpose: To determine the toxicity, tolerability, pharmacokinetics, pharmacodynamics, and preliminary antitumor activity of oral gemcitabine (2',2'-difluorodeoxycytidine; dFdC) in patients with cancer.

Experimental design: Patients with advanced or metastatic cancer refractory to standard therapy were eligible. Gemcitabine was administered p.o. starting at 1 mg once daily using dose escalation with three patients per dose level. Patients received one of two dosing schemes: (a) once daily dosing for 14 days of a 21-day cycle or (b) every other day dosing for 21 days of a 28-day cycle. Pharmacokinetics were assessed by measuring concentrations of dFdC and 2',2'-difluorodeoxyuridine (dFdU) in plasma and gemcitabine triphosphate in peripheral blood mononuclear cells, and pharmacodynamics by measuring the effect on T-cell proliferation.

Results: Thirty patients entered the study. Oral gemcitabine was generally well-tolerated. The maximum tolerated dose was not reached. Mainly moderate gastrointestinal toxicities occurred except for one patient who died after experiencing grade 4 hepatic failure during cycle two. One patient with a leiomyosarcoma had stable disease during 2 years and 7 months. Systemic exposure to dFdC was low with an estimated bioavailability of 10%. dFdC was highly converted to dFdU, probably via first pass metabolism and dFdU had a long terminal half-life ( approximately 89 h). Concentrations of dFdCTP in peripheral blood mononuclear cells were low, but high levels of gemcitabine triphosphate, the phosphorylated metabolite of dFdU, were detected.

Conclusions: Systemic exposure to oral gemcitabine was low due to extensive first-pass metabolism to dFdU. Moderate toxicity combined with hints of activity warrant further investigation of the concept of prolonged exposure to gemcitabine.

Publication types

  • Clinical Trial, Phase I

MeSH terms

  • Administration, Oral
  • Adult
  • Aged
  • Antimetabolites, Antineoplastic / administration & dosage*
  • Antimetabolites, Antineoplastic / adverse effects
  • Antimetabolites, Antineoplastic / pharmacokinetics*
  • Area Under Curve
  • Cell Proliferation / drug effects
  • Deoxycytidine / administration & dosage
  • Deoxycytidine / adverse effects
  • Deoxycytidine / analogs & derivatives*
  • Deoxycytidine / pharmacokinetics
  • Drug Administration Schedule
  • Female
  • Gemcitabine
  • Humans
  • Male
  • Maximum Tolerated Dose
  • Middle Aged
  • Neoplasms / drug therapy*
  • T-Lymphocytes / drug effects


  • Antimetabolites, Antineoplastic
  • Deoxycytidine
  • Gemcitabine