Optimal tolerability and high efficacy of a modified schedule of lapatinib-capecitabine in advanced breast cancer patients.

Purpose: Diarrhea in relation to the lapatinib-capecitabine regimen is a common and debilitating side effect which may interfere with optimal treatment delivery. We performed a post hoc analysis in human epidermal growth factor receptor 2-positive advanced breast cancer patients treated with a modified schedule in its administration, aimed primarily to evaluate grade (G) ≥ 2 diarrhea incidence and, secondarily, treatment efficacy.

Patients And Methods: Treatment schedule consisted of lapatinib 1,250 mg daily for the first 10 days, then in combination with capecitabine, 2,000 mg/m(2), starting day 11 for the first cycle, and thereafter from day 8, for 14 days of a 21-day cycle, in 3 daily administrations. Lapatinib was dissolved in water, and cholestyramine was continuously given twice a day.

Results: Among 38 patients treated and analyzed, the incidence of G ≥ 2 diarrhea was 13.2 %. In 28 patients diarrhea was not observed, while G1-2 diarrhea was reported in 9 (23.7 %) patients; a single episode of G3 diarrhea was observed in 1 (2.6 %) patient. Overall response rate was 34.2 %, clinical benefit 55.3 %, and median progression-free survival 10 months.

Conclusion: The results of the present post hoc analysis are very encouraging, both in terms of tolerability and treatment efficacy, and all data compare favorably with previous reports of "conventional" administration of the lapatinib-capecitabine regimen.