A pharmacodynamic study of docetaxel in combination with the P-glycoprotein antagonist tariquidar (XR9576) in patients with lung, ovarian, and cervical cancer

Ronan J. Kelly, Deborah Draper, Clara C. Chen, Robert W. Robey, William D. Figg, Richard L. Piekarz, Xiaohong Chen, Erin R. Gardner, Frank M. Balis, Aradhana M. Venkatesan, Seth M. Steinberg, Tito Fojo, Susan E. Bates

Research output: Contribution to journalArticlepeer-review

Abstract

Purpose: P-glycoprotein (Pgp) antagonists have been difficult to develop because of complex pharmacokinetic interactions and a failure to show meaningful results. Here we report the results of a pharmacokinetic and pharmacodynamic trial using a third-generation, potent, noncompetitive inhibitor of Pgp, tariquidar (XR9576), in combination with docetaxel. Experimental Design: In the first treatment cycle, the pharmacokinetics of docetaxel (40 mg/m2) were evaluated after day 1 and day 8 doses, which were administered with or without tariquidar (150 mg). 99mTc-sestamibi scanning and CD56 + mononuclear cell rhodamine efflux assays were conducted to assess Pgp inhibition. In subsequent cycles, 75 mg/m2 docetaxel was administered with 150 mg tariquidar every 3 weeks. Results: Forty-eight patients were enrolled onto the trial. Nonhematologic grade 3/4 toxicities in 235 cycles were minimal. Tariquidar inhibited Pgp-mediated rhodamine efflux from CD56 + cells and reduced 99mTc-sestamibi clearance from the liver. There was striking variability in basal sestamibi uptake; a 12% to 24% increase in visible lesions was noted in 8 of 10 patients with lung cancer. No significant difference in docetaxel disposition was observed in pairwise comparison with and without tariquidar. Four partial responses (PR) were seen (4/48); 3 in the non-small cell lung cancer (NSCLC) cohort, measuring 40%, 57%, and 67% by RECIST, and 1 PR in a patient with ovarian cancer. Conclusions: Tariquidar is well tolerated, with less observed systemic pharmacokinetic interaction than previous Pgp antagonists. Variable effects of tariquidar on retention of sestamibi in imageable lung cancers suggest that follow-up studies assessing tumor drug uptake in this patient population would be worthwhile.

Original languageEnglish (US)
Pages (from-to)569-580
Number of pages12
JournalClinical Cancer Research
Volume17
Issue number3
DOIs
StatePublished - Feb 1 2011
Externally publishedYes

ASJC Scopus subject areas

  • Oncology
  • Cancer Research

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