A phase I study of nolatrexed dihydrochloride in children with advanced cancer. A United Kingdom Children's Cancer Study Group Investigation

A phase I study of nolatrexed, administered as a continuous 5 day intraveno us infusion every 28 days, has been undertaken for children with advanced m alignancy. 16 patients were treated at 3 dose levels; 420, 640 and 768 mg/m (2) 24 h(-1), 8 patients were evaluable for toxicity. In the 6 patients tre ated at 768 mg/m(2) 24 h(-1), dose-limiting oral mucositis and myelosuppres sion were observed. Plasma nolatrexed concentrations and systemic exposure, measured in 14 patients, were dose related. with mean AUC values of 36 mg( -1) ml(-1) min(-1), 50 mg ml(-1) min(-1) and 80 mg ml(-1) min(-1) at the 3 dose levels studied. Whereas no toxicity was encountered ii the nolatrexed AUC was <45 mg ml(-1) min(-1), Grade 3 or 4 toxicity was observed with AUC values of >60 mg ml(-1) min(-1). Elevated plasma deoxyuridine levels, measu red as a surrogate marker of thymidylate synthase inhibition, were seen at all of the dose levels studied. One patient with a spinal primitive neuroec todermal tumour had stable disease for 11 cycles of therapy. and in two pat ients with acute lymphoblastic leukaemia a short-lived 50% reduction in per ipheral lymphoblast counts was observed. Nolatrexed can be safely administe red to children with cancer, and there is evidence of therapeutic activity as well as antiproliferative toxicity. Phase II studies of nolatrexed in ch ildren at the maximum tolerated dose of 640 mg/m2 24 h(-1) are warranted. ( C) 2001 Cancer Research Campaign http://www.bjcancer.com.