Imatinib Mesylate (IM) Versus IM + Low Dose of Pegylated Interferon Alfa 2a (Peg-IFN 2a) In Newly-Diagnosed Chronic-Phase (CP) Chronic Myeloid Leukemia (CML).

Abstract

4497 Background: IM 400mg daily is the current standard of treatment of CP CML. Almost 70% of patients achieve complete cytogenetic response (CCR) at 12 months (mo) (IRIS Trial) and the rate of Major Molecular Response (MMR) is 40% with IM 400mg daily (TOPS Trial). On the other hand, low doses of Peg-IFN 2a has the same efficacy and lower toxicity profile and cost as high dose, mainly when it is combined with other drugs (MRC and Hovon groups, Blood 2004; 103:4408). Combination of IM + Peg-IFN 2a or Cytarabine could increase the rate of response in CML. Aims: To evaluate the rates of CCR and MMR at 12 mo in Mexican patients with newly-diagnosed CP-CML treated with IM versus IM + Peg-IFN 2a. Methods: Between 2006 and 2008, 10 patients were randomized 1:1 and stratified by Sokal and Hasford risk groups. Cytogenetic and Molecular assesments were available for all patients. In the arm A of the study IM 400 mg daily was delivered. In the Arm B IM + Peg-IFN 2a was delivered at 400 mg daily + 90 μ g per week respectively. Peg-IFN 2a was started in the 7th week of treatment (Hochhaus A, et al ASCO 2003. Abstract #2287). Results: For this initial report, 10 patients were analyzed, median age was 35 years (25-55), 50% males; Sokal score was: low risk 70%, and high risk 30%. Hasford score was: low risk 40%, intermediate 30% and high risk 30%. All patients are alive with a median follow-up of 41 mo (30-48). CCR at 12 mo was obtained in 80% in both arms of treatment. MMR was obtained in 10% in patients with IM alone and 30% in patients with IM + Peg-IFN 2a. Overall the rate of primary resistance was 10% and the rate of suboptimal response was 10%. IM 400 mg was well tolerated. Peg-IFN 2a was tolerated in most patients, but needed discontinuation because increased cytopenias or other non hematologic toxicities. The median time of duration of treatment with Peg-IFN 2a was 6 mo (3-12). Conclusions: IM 400 mg and IM 400 mg + Peg-IFN 2a obtained similar rates of CCR. IM 400 mg + Peg-IFN 2a obtained a higher rate of MMR. The combination of IM 400 mg + Peg-IFN 2a is feasible. There is a slight increase in toxicity with this combination. Further follow-up is warranted for these patients. Disclosures: No relevant conflicts of interest to declare.