Objective:To investigate the clinical effect and safety of dasatinib combined with Chinese Children's Leukemia Group-acute lymphoblastic leukemia (CCLG-ALL) 2008 protocol in treatment of childhood Philadelphia chromosome-positive (Ph⁺) acute lymphoblastic leukemia (ALL).

Methods:The clinical data of 22 patients with Ph⁺ ALL who were newly diagnosed at the age of less than 15 years old in Fujian Medical University Union Hospital from January 2014 to December 2018 were retrospectively analyzed. All patients were treated with dasatinib combined with CCLG-ALL2008 protocol (high-risk group). The patients were assigned to two groups according to different starting times of oral dasatinib: the dasatinib-induced group (starting from day 15 of induction chemotherapy) and the dasatinib-consolidated group (starting with early consolidated chemotherapy). The early treatment response and 5-year event-free survival (EFS) rate were compared between the two groups.

Results:The differences of clinical characteristics and early efficacy of chemotherapy before treatment of dasatinib between the two groups were not statistically significant (both P > 0.05). The complete remission (CR) rate on day 33 of induction chemotherapy was higher in the dasatinib-induced group than that in the dasatinib-consolidated group [100% (10/10) vs. 75% (9/12)], but the difference was not statistically significant (χ ²= 2.895, P= 0.221). The rate of minimal residual disease (MRD) turned negative (<0.01%) on day 33 of induction chemotherapy in the dasatinib-induced group was significantly higher than that in the dasatinib-consolidated group [70% (7/10) vs. 17% (2/12)], and the difference was statistically significant (χ ²= 6.418, P= 0.027). The 3-year EFS rate was higher in the dasatinib-induced group than that in the dasatinib-consolidated group (88.9% vs. 63.5%), but the difference was not statistically significant (P= 0.163). The incidence of grade 3-4 infection in the dashatinib-induced group was lower than that in the dasatinib-consolidated group, and the difference was statistically significant [60% (6/10) vs. 100% (12/12), P= 0.029]. the other grade 3-4 adverse reactions related to the chemotherapy drugs mainly included hematological toxicity, diarrhea, abnormal liver function, edema and pleural effusion, but there was no significant difference between the two groups (all P > 0.05).

Conclusions:Dasatinib combined with CCLG-ALL2008 protocol in the treatment of children with Ph⁺ ALL has good efficacy and safety. Furthermore, the early use of dasatinib on day 15 of induction chemotherapy can enable patients to achieve deeper remission earlier and improve long-term efficacy.