Concurrent radiation with irinotecan and carboplatin in intermediate- and high-risk rhabdomyosarcoma: A report on toxicity and efficacy from a prospective pilot phase II study

Background: Irinotecan is highly active against rhabdomyosarcoma (RMS), yet its tolerability and efficacy in combination with radiation is unknown. We examined local control and toxicities in RMS patients treated with radiotherapy (RT) in combination with radiosensitizing agents irinotecan+carboplatin (I+C). Procedure: From 11/2003 to 1/2011, 60 patients were enrolled on a pilot phase II protocol with newly diagnosed intermediate- or high-risk RMS at Memorial Sloan-Kettering Cancer Center. Induction therapy consisted of two cycles of I+C followed by three cycles of vincristine, doxorubicin, and cyclophosphamide. At week 13, 47 patients received definitive primary-site RT or post-operative RT with two concurrent cycles of I+C. Median RT dose was 50.4Gy (range 30.6-50.4Gy). Radiation-related toxicities were evaluated according to the Common Terminology Criteria for Adverse Events, version 3.0. Results: Median age of the cohort was 9 years. With median follow-up of 32 months, 2.5 year actuarial local control was 89%. Among all patients, grades 3 and 4 dermatitis were observed in 11% and 4%, respectively. Among parameningeal, orbit, and other head/neck sites, rates of grades 3 and 4 mucositis were 20% and 10%, respectively. Among abdomen/pelvis sites, 12% developed grade 3 diarrhea and 6% developed grade 3 cystitis. No treatment breaks were necessary. Conclusions: Preliminary results of irinotecan and carboplatin administered with concurrent RT in intermediate- and high-risk RMS demonstrated favorable tolerability, efficacy, and local control. Reduced rates of acute grades 3-4 mucositis were observed when compared with historical results.