[Phase II study of a new nitrosourea derivative, MCNU, in tablet form. Takai Blood Cancer Study Group]

A phase II study of the oral agent methyl 6-[3-(2-chloroethyl)-3-nitrosoureido]-6-deoxy-alpha-D-glucopyranoside (MCNU tablet) for myeloproliferative disorders was performed. Fifty-two patients were treated with MCNU tablets and 43 patients were evaluated for clinical effects and 45 for adverse effects. The standard regimen was as follows; oral administration of 50mg (one tablet)/body/day every 4-6 days was considered as one course, and this was repeated at 6-8-week intervals if possible, with certain modifications according to dosage, period of administration and dose interval wherever necessary. Of 16 patients with chronic myelogenous leukemia (CML) in the chronic phase, 13 achieved complete remission (CR), and 3 achieved partial remission (PR). The overall response ratio was 100%. Rapid reduction of leucocytes was detected within two weeks. One patient with CML in blast crisis achieved PR (100%). Of 15 patients with polycythemia vera, 13 showed an excellent effect (87%), and 1 a moderate effect (6.7%), the overall response ratio being 93%. In essential thrombocythemia, an excellent effect (70%) was obtained in 7 of 10 patients. One patient with myelofibrosis showed an excellent effect (100%). Nausea & vomiting (33%) and anorexia (13%) were major adverse effects, but these symptoms were observed only transiently. Liver dysfunction was also seen in 8.9% of patients, but no patient showed severe manifestations. Our study supports the contention that MCNU tablet is a useful agent against myeloproliferative disorders.