Treatment of philadelphia chromosome-positive early chronic phase chronic myelogenous leukemia with daily doses of interferon alpha and low- dose cytarabine

Purpose: To evaluate the efficacy of the combination of interferon alpha (IFN-α) and daily low-dose cytarabine (ara-C) in the treatment of patients with early chronic-phase chronic myelogenous leukemia (CML) (within 1 year of diagnosis). Improving the degree of hematologic and cytogenetic response in patients with Philadelphia chromosome (Ph)-positive CML may improve prognosis. Bath IFN-α and ara-C induce cytogenetic responses as single- agent therapy in CML. Patients and Methods: One hundred forty patients with Ph-positive early chronic-phase CML received subcutaneous injections of IFN- α 5 megaunits/m² daily and ara-C 10 mg daily. Their median age was 46 years; 53% had good-risk disease, 33% had intermediate-risk disease, and 14% had poor-risk disease. Their results were compared with those of patients receiving IFN-α with or without intermittent ara-C (7 days/mo). Results: A complete hematologic response (CHR) was achieved in 92% of patients. A cytogenetic response was seen in 74%: it was major in 50% (Ph-positive < 35%) and complete in 31% (Ph-positive 0%). With a median follow-up of 42 months, the 4-year estimated survival rate was 70% (95% confidence interval, 61% to 79%). Significant side effects included fatigue (43%; grade 3/4, 11%), weight loss (19%; grade 3/4, 11%), muscle and bone aches (20%; grade 3/4, 7%), oral ulcers (4%), diarrhea (6%), and neurologic changes (27%, grade 3/4, 6%). The median dose of IFN-α was 3.7 megaunits/m² daily, mainly because of reductions for myelosuppression (70% of cases); the median ara-C dose was 7.5 mg daily. Prognostic risk groups were predictive for response to the IFN-α plus ara-C combination. The incidence of CHR was higher with IFN-α plus daily ara-C compared with IFN-α plus intermittent ara-C and IFN-α alone (no ara-C) (92% v 84% v 80%, P = .01), as were the incidences of cytogenetic response (74% v 73% v 58%; P = .003) and major cytogenetic response (50% v 38% v 38%; P = .06). The median time to achievement of major cytogenetic response was significantly shorter than that for previous IFN-α regimens (7 v 10 v 12 months; P < .01). However, with the present follow-up, the survival and time to blastic transformation were similar. Conclusion: The combination of IFN-α plus daily low-dose ara-C seems to be promising for the treatment of CML. High rates of CHR and cytogenetic response were observed with acceptable toxicity and a lower daily dose of IFN-α compared with our previous studies.