Efficacy and prognostic factors of imatinib plus CALLG2008 protocol in adult patients with newly diagnosed Philadelphia chromosome-positive acute lymphoblastic leukemia

A CALLG2008 protocol was developed by the Chinese Acute Lymphoblastic Leukemia Cooperative Group for adult acute lymphoblastic leukemia (ALL). We retrospectively analyzed 153 newly diagnosed adult patients with Philadelphia chromosome (Ph)-positive ALL enrolled into imatinib (400 mg/d) plus CALLG2008 regimen between 2009 and 2015. The median age was 40 years (range, 18-68 years), with 81 (52.3%) males. The overall hematologic complete remission (CR) rate was 96.7% after induction. With a median follow-up of 24.2 months, the estimated 3-year overall survival (OS) and event-free survival (EFS) rates were 49.5%(95% confidence interval (CI): 38.5%-59.5%) and 49.2% (95% CI: 38.3%-59.2%), respectively. Fifty-eight (36 with haploidentical donor) patients underwent allogeneic hematopoietic stem cell transplantation (allo-HSCT) in first CR. Among the patients in CR1 after induction, both the 3-year OS and EFS were significantly better in the allo-HSCT group than in the without allo-HSCT group (73.2%, 95% CI: 58.3%-83.5% vs. 22.2%, 95% CI: 8.7%-39.6% and 66.5%, 95% CI: 50.7%-78.2% vs. 16.1%, 95% CI: 5.1%-32.7%, respectively). Multivariate analysis showed that allo-HSCT and achievement of major molecular response were associated with favorable OS or EFS independently. Interestingly, in the allo-HSCT cohort, the donor type (haploidentical versus matched donors) had no significant impact on EFS or OS. All these results suggested that imatinib plus CALLG2008 was an effective protocol for Ph-positive ALL. Haploidentical donors can also be a reasonable alternative expedient donor pool.