Improved prognosis in mice with advanced myeloid leukemia following administration of GM-CSF and cytosine arabinoside.

Acute myeloid leukemia (AML) was induced in C57Bl mice through the i.v. innoculation of C-1498 cell line. One week later, i.e. at mid-term disease, the leukemic mice received an i.p. injection of 200 ng rmGM-CSF and 24 h later, two consecutive i.p. cytosine arabinoside (ara-C) injections at 6 h intervals (2 x 200 mg/kg). The leukemic mice received 3-4 weekly courses of combined therapy and survived 4-5 weeks following leukemia induction. Control mice received ara-C only and survived 2-3 weeks. Moreover, leukemic mice administered both GM-CSF and ara-C had a lower marrow leukemic load than mice treated with ara-C only. From these findings, we conclude that therapy of murine AML with combined rmGM-CSF and ara-C is more effective than ara-C only. Leukemic mice treated with GM-CSF and ara-C had a longer life expectancy and a smaller leukemic load than mice administered ara-C only.