The therapeutic efficacy of pediatric ALL patients with MLL gene rearrangement treated with CCLG-ALL2008 protocol.

OBJECTIVE: In this study, we retrospectively evaluated the therapeutic efficacy of China Children Leukemia Group-ALL2008 (CCLG-ALL 2008) protocol in pediatric patients with mixed-lineage leukaemia (MLL) gene rearrangement of acute lymphoblastic leukemia (ALL) to identify the prognostic factors.

PATIENTS AND METHODS: Six hundred and thirty-four patients with ALL were enrolled in this study between June 2008 and Dec 2014. High-risk group (HR) consisted of 217 cases, of which 28 cases were MLL related positive (first group), 22 cases were BCR/ABL positive (second group), and 167 cases were negative with MLL related or BCR/ABL (third group). The therapeutic efficacy was evaluated at the time points of day 8 (TP1), day 15 (TP2), day 33 (TP3) and 12th week (TP4) with the protocol, respectively. Overall-survival (OS) and relapse-free-survival (RFS) and treatment-related mortality (TRD) were analyzed as well.

RESULTS: The first group accounted for 4.4% of all patients. Compared with the second and third group, the first group had more cases younger than 2 years, with initial leukocytes ≥50×109/L, and poor response on TP2. Moreover, patients older than 2 years old had a good 5 years OS (84% ± 9% vs. 37% ± 20%, p<0.05) and RFS (84% ± 9% vs. 29% ± 17%, p<0.05). There were no significant differences in the recurrence rate, TRD, 5 years OS and RFS among three groups. For the first group, compared with good response to prednisone, patients with poor response to prednisone had a poor 5 years RFS (41% ± 17% vs. 81% ± 10%, p<0.05). Multivariate Cox regression analysis identified that RFS and OS were influenced by such factors as age, MLL fusion partners, and prednisone response (p<0.05).

CONCLUSIONS: Such factors as younger age than 2 years old, MLL/AF4 fusion gene, poor response to prednisone, or no complete remission (CR) on TP3 were poor prognostic parameters in predicting the outcome in childhood ALL with MLL gene rearrangement treated with CCLG-ALL 2008 protocol.