Phase II trial of recombinant human interferon alpha in myelodysplastic syndromes.

Twenty patients with myelodysplastic syndromes were treated with daily subcutaneous injections of interferon alpha 2a, at the initial dose of 3 x 10(6) U/m2. Hemogram, chemistry profile, natural killer (NK) cell activity and lymphokine-activated killer (LAK) cell cytotoxicity were monitored serially. Bone marrow with cytogenetic analysis was done before therapy and every three months afterwards. Normalization to the complete blood count, and wherever applicable, decrease in blast count of 5% or less were defined as a complete response. Improvement in hemoglobin level to 12 g/dl, neutrophil count to 1000/mm3 and platelets to 100,000/mm3 was considered a partial response. The median age was 71 (range 59-83) years and 16 of the patients were males. Two patients withdrew from the treatment in the first week and were considered ineligible. Among the other 18, two had refractory anemia, two refractory anemia with ringed sideroblasts, four chronic myelomonocytic leukemia, eight refractory anemia with excess blasts, and two refractory anemia with excess blasts in transformation to acute leukemia. Twelve patients were treated for six months, the other six were taken off the treatment after six to eight weeks because of disease progression. Only one patient with chronic myelomonocytic leukemia had a partial response for two months. NK cell activity remained unchanged before (18.3 +/- 4.6 lytic units) and during interferon therapy (19.6 +/- 5.3 lytic units). LAK cytotoxicity was not detected in any patient before therapy and was seen in only one patient (not the responder) during therapy (5.7 lytic units). The toxicity of the interferon therapy was substantial. Seventeen patients required a dose reduction and fifteen lost greater than 10% of body weight. Eleven patients (61%) developed infections requiring antibiotic therapy, and eight (44%) required hospitalization. Seven patients developed neurologic toxicity. Interferon alpha 2a is an ineffective but toxic therapy in these elderly patients with myelodysplastic syndromes.