Camptothecin schedule and timing of administration with irradiation

The camptothecins are a new class of chemotherapeutic radiation sensitizers , Clinical trials with camptothecins alone show higher toxicity than predic ted by preclinical models, which has created the challenge of finding new w ays to widen the therapeutic window, Camptothecin dose, schedule, and timin g with irradiation are important factors that need to be considered in the design of new studies with these S-phase agents, Data are reviewed from ear ly phase I and II chemoradiation trials, including a multicenter, phase II study planned by the Radiation Therapy Oncology Group (RTOG) in operable re ctal cancer using irinotecan (CPT-II, Camptosar), One novel approach (based on preclinical observations) with the potential to widen the therapeutic w indow may be the use of a chronomodulated camptothecin delivery schedule wi th irradiation.