Recombinant human granulocyte-macrophage colony-stimulating factor and low-dose cytosine arabinoside in patients with myelodysplastic syndrome. A pilot study.

In a pilot study, five patients with myelodysplastic syndromes with an excess of blast cells were treated with a combination of recombinant human granulocyte-macrophage colony-stimulating factor (rhGM-CSF) and low-dose cytosine-arabinoside (ara-C) in an attempt to selectively kill the leukemic blast cells and thereby to restore normal hemopoiesis. The treatment schedule consisted of three 14-day-cycles of 250 micrograms/m2 rhGM-CSF and 20 mg/m2 ara-C given daily s.c. with four-week treatment-free intervals. In all four evaluable patients the percentage of bone marrow blast cells decreased significantly with an increase in the mature myeloid cells but without bone marrow aplasia. Toxic side effects attributable to the drugs were minor with fever, mild bone pain, erythema and itching at the site of subcutaneous injection of rhGM-CSF. In conclusion, the combined therapy of rhGM-CSF and low-dose ara-C appears to be effective in the short-term control of the leukemic cell population.