Comparison of Combination Therapy of Imatinib with Trisenox Versus Imatinib Monotherapy for Chronic Myeloid Leukemia Patients in Chronic Phase.

Targeted therapy with the Bcr-Abl tyrosine kinase inhibitor Imatinib Mesylate can induce high response rates in chronic myelogenous leukemia (CML) patients. However, evidences that discontinuation of imatinib mesylate inevitably exerts rapid loss of response and some patients with imatinib mesylate monotherapy virtually occur potential relapse suggest that the modification of treatment strategy is critical. We have previously demonstrated that the combination of trisenox (arsenic trioxide) with the tyrosine kinase inhibitor imatinib mesylate or genistein appears to induce markedly more cell apoptosis than imatinib mesylate alone through downregulating Bcl-X_L and Bcr-Abl in Bcr-Abl gene transfected HL-60 cells. We here report the preliminary results of a pilot study comparing imatinib mesylate plus trisenox with imatinib mesylate alone for frontline treatment of CML patients.

Up to date 56 patients were enrolled in this clinical trail. All patients (required to be 18 years or older with Bcr-Abl positive CML in chronic phase within three month of diagnosis) were divided into two groups, i.e., monotherapy group and combined therapy group. 42 patients entering monotherapy received imatinib mesylate 400mg daily and 14 patients entering combined therapy imatinib mesylate 400mg daily plus trisenox 10mg daily for one week and then twice a week. We compared treatment results of both groups including complete hematologic response(CHR), major/complete cytogenetic response(MCR/CCR),--defined as 1–35% Ph⁺ and 0% Ph⁺ metaphases respectively and major/complete molecular response(MMR/CMR),--defined as ≥ 3 log reduction and negative expression in Bcr-Abl transcript numbers assayed by RQ-PCR respectively. The median follow-up for patients in both groups lasted 36 months. In the combined therapy group, the median age of patients is 42 years old (range, 22–61), the CHR, MCR, CCR, MMR and CMR is 92.8%, 64.3%, 42.9%, 35.7% and 21.4%, respectively. While in the imatinib mesylate monotherapy group, the median age of patients is 46 years old (range, 23–65), the CHR, MCR, CCR, MMR and CMR is 85.7%, 59.5%, 40.5%, 33.3% and 19%, respectively.

Although combination therapy of imatinib with trisenox is not significantly superior to imatinib mesylate monotherapy in efficacy, no resistance case happens in the combination therapy group, in the imatinib mesylate monotherapy group, imatinib resistance occurs in 4 patients. In addition, the safety and tolerability of a combination of imatinib mesylate and trisenox is good. This result indicates that the combination of imatinib and trisenox to treat chronic myeloid leukemia may be promising in avoiding the occur of imatinib resistance.