[A phase II study of N4-palmitoyl-1-beta-D-arabinofuranosylcytosine (PL-AC) in patients with acute leukemia and myelodysplastic syndromes. Cooperative Study Group for PL-AC].

N4-Palmitoyl-1-beta-D-arabinofuranosylcytosine (PL-AC) was administered p.o. to 199 patients with acute leukemia, myelodysplastic syndromes (MDS) and myeloproliferative disorders (MPD). Of 76 patients with AML, 11 achieved complete remission (CR) and 7 achieved partial remission (PR). Of 8 patients with ALL, 2 achieved CR and 1 achieved PR. Of 3 patients with blast crisis of MPD, 1 achieved CR. CR was reached with PL-AC at 100-900 mg/day after 5-98 (median 26) days. Of 50 patients with MDS, 2 achieved CR, 2 showed good response and 7 partial response. Response was reached with 100-400 mg/day after 13-122 (median 32) days. Improvement of polycythemia vera was observed in 6 of 13 patients, and reduction of thrombocytosis was observed in 20 of 23 patients with essential thrombocythemia and myelofibrosis. Of 18 patients with CML, 1 achieved CR. Major side effects were GI toxicities and myelosuppression. In spite of the disadvantages of the oral form of the drug, such as unpredictable absorption, PL-AC may be useful in the treatment of acute leukemia, especially that of the aged, a condition for which intensive chemotherapy is not always indicated, and MDS, which do not necessarily require admission to a hospital.