Safety and efficacy of an indigenous recombinant interferonalpha-2b in patients with chronic myelogenous leukaemia: results of a multicentre trial from India

Abstract

Background: Compared to hydroxyurea, treatment with interferon-α (IFN-α) is known to prolong survival in patients with chronic phase of chronic myelogenous leukaemia (CML) and was considered as first-line therapy till recently. We conducted a multicentre trial using an indigenous recombinant IFN-α-2b to evaluate its efficacy and toxicity in chronic phase CML. Methods: Between September 2000 and August 2001, patients with chronic phase CML were recruited within 8 weeks of diagnosis at 7 centres in India. The study was approved by the Ethics Committee of each participating Institute and Informed, written consent was obtained from all patients. All patients were given the study drug in a dose of 5 million units daily subcutaneously. Response and survival analyses were done with intent-to-treat analysis. Results: One hundred and fourteen patients (75 men and 39 women) were included in the study. Their ages ranged from 18 to 62 years (median 37 years). Fifty-seven per cent of patients had a haematological response; complete response in 31.6% and partial response in 25.4%. The median time to achieve complete haematological response was 6 months (range 3-12 months). Cytogenetic response was seen in 39.4% of patients; complete in 1.8%, partial in 28% and minimal in 9.6%. The median time to achieve partial and complete cytogenetic response was 6 and 12 months, respectively. Nineteen patients had progression (blast crisis n=15, accelerated phase n=4) while on treatment. Two patients refused further treatment after the initial 4 weeks due to IFN- α toxicity, mainly bone pains and fever. The major toxic effects of treatment were fever (78%), fatigue (25.4%) and myalgia (52%). No patient died of toxicity. Currently, 95 patients are alive, 91 in the chronic phase and 4 in the accelerated phase. Four patients were lost to follow up and all 15 patients with blast crisis died of progressive disease at a median Interval of 6.5 months (range 1-15 months). The Kaplan-Meier probability of survival at 36 months was 76%. Conclusions: This study confirms the efficacy of the indigenous recombinant IFN- α-2b in chronic phase CML. The drug has a toxicity profile similar to that of other preparations.