Phase I and pharmacokinetic study of oral irinotecan given once daily for 5 days every 3 weeks in combination with capecitabine in patients with solid tumors.

Purpose: To assess the maximum tolerated dose, dose-limiting toxicity, pharmacokinetics, and preliminary antitumor activity of oral irinotecan given in combination with capecitabine to patients with advanced, refractory solid tumors.

Patients And Methods: Patients were treated from day 1 with irinotecan capsules given once daily for 5 consecutive days (50 to 60 mg/m2/d) concomitantly with capecitabine given twice daily for 14 consecutive days (800 to 1,000 mg/m2); cycles were repeated every 21 days.

Results: Twenty-eight patients were enrolled and received 155 cycles of therapy (median, five cycles; range, one to 18 cycles). With irinotecan 60 mg/m2/d and capecitabine 2 x 800 mg/m2/d, grade 3 delayed diarrhea in combination with grade 2 nausea (despite maximal antiemetic support) and grade 3 anorexia and colitis, were the first-cycle dose-limiting toxicities in two of six patients, respectively. At the recommended doses (irinotecan 50 mg/m2/d; capecitabine 2 x 1,000 mg/m2/d), side effects were mostly mild to moderate and uniformly reversible. Pharmacokinetic analysis showed that there was no interaction between oral irinotecan and capecitabine, and that body-surface area was not significantly contributing to the observed pharmacokinetic variability. Confirmed partial responses were observed in two patients with gallbladder carcinoma and in one patient with melanoma. Disease stabilization was noted in 16 patients.

Conclusion: The recommended phase II doses for oral irinotecan and capecitabine are 50 mg/m2/d for 5 consecutive days, and 2 x 1,000 mg/m2/d for 14 consecutive days repeated every 3 weeks, respectively.