Objective: To investigate the clinical effect of chronic myelocytic leukemia (CML) patients treated with imatinib (IM) and interferon (IFN)-α.
Methods: One hundred and fifty five CML patients at chronic phase were included in the study. All patients were divided into two groups according to treatment regimen: IM + IFN group and IM group. Complete cytogenetic response (CCyR) rate, major molecular response (MMR) rate, complete molecular response (CMR) rate, overall survival (OS) and progression free survival (PFS) were observed and compared in both groups.
Results: The CCyR rate was higher in the IM + IFN group than that in the IM group at 6 months (60.6% vs 41.6%, P < 0.05), but no difference was observed later on. The MMR + CMR rate was higher in the IM + IFN group than that in the IM group at 6 months and 12 months (71.2% vs 34.8%, 77.3% vs 52.8%, respectively, P < 0.05), but no difference after that. After stratification according to Sokal risk, the CCyR rate of low- and intermediate-risk patients was higher in the IM + IFN group than that in the IM group at 6 months (77.8% vs 52.6%, 75.0% vs 46.7%, P < 0.05), but not from 12 months on; the MMR + CMR rate of low- and intermediate-risk patients was higher in the IM + IFN group than that in the IM group at 6 months and 12 months (85.2% vs 36.8%, 90.0% vs 36.7%, P < 0.05; 88.9% vs 57.9%, 90.0% vs 56.7%, P < 0.05), but not from 24 months on. There was no significant difference in high-risk patients. OS in IM and IM + IFN group at 6, 12, 24 and 36 months was 100%, 100%, 96.8% and 90.0%, and 100%, 100%, 97.9% and 93.1%, respectively. PFS in IM and IM + IFN group at 6, 12, 24 and 36 months was 97.8%, 95.5%, 91.9% and 85.5%, and 98.5%, 95.5%, 91.5% and 86.2%, respectively. There was no significant difference in OS (u = 0.427, P = 0.514) or PFS (u = 0.556, P = 0.456). The side effects in both groups included pancytopenia, edema, weight gain, ostalgia, rash and muscle spasm. In addition, patients in the IM + IFN group suffered from flu-like symptoms, impaired liver function, abnormal thyroid function and extremity sensory disturbance. It seemed that grade III or IV pancytopenia occurred more commonly in the patients in the IM + IFN group, however, there was no statistically significance.
Conclusions: The response to IM + IFN is more rapid than that to IM alone, especially for the low- and intermediate-risk patients. It seems no benefit of the addition of IFN to treatment of high-risk patients. During the period of 36 months, survival rate in the IM + IFN group is not higher than that in IM group, and it is possible to increase the side effects of pharmaceutical drugs.