Acute lymphoblastic leukemia in children with Down syndrome: comparative analysis of treatment results according to ALL-MB 2008 and ALL-MB 2015 protocols

Introduction. Down syndrome (DS) is one of the most common chromosomal abnormalities. Children with DS have an increased risk of developing acute lymphoblastic leukemia (ALL). Standard therapy is usually used to treat ALL in children with Down syndrome, but the outcome is worse than in the general population. The high toxicity of therapy is a particular problem.The purpose of the study – in this study we presents a comparative analysis of the results of therapy for children with DS and ALL (DS-ALL) who received therapy according to the ALL-MB 2008 and ALL-MB 2015 protocols.Materials and methods. The analysis included primary ALL patients, aged 1 to 18 years, who received therapy in Russian and Belarusian clinics participating in the Moscow–Berlin study from January 2008 to December 2020. To analyze the treatment results of DS-ALL patients, a “comparison group” was formed from all patients with ALL registered in the database, using the matched-pair method. Survival was calculated using the Kaplan–Meier method, toxicity analysis and clinical-genetic parameters were investigated using nonparametric statistical methods.Results. The results of therapy both among patients with DS-ALL who received therapy according to ALL-MB 2008 and ALL-MB 2015 in comparison with “sporadic” ALL (non-DS-ALL) are unsatisfactory. The event-free survival rate of patients with DS-ALL in the ALL-MB 2008 group was 61 ± 7 % versus 85 ± 4 % among non-DS-ALL (p = 0.001), in the ALL-MB 2015 group – 67 ± 7 % versus 84 ± 4 % respectively. Overall survival in the ALL-MB 2008 group was 70 ± 7 % in children with DS versus 88 ± 4 % in non-DS (p < 0.001), in the ALL-MB 2015 group – 78 ± 6 % versus 92 ± 3 % respectively (p < 0.001). The risk of therapy-related death was higher in patients with DS: 20.6 ± 6.1 % versus 4.6 ± 2.2 %; p < 0.001 in the ALL-MB 2008 group and 18 ± 4.1 % versus 3.3 ± 1.3 %; p < 0.001 in the ALL-MB 2015 group, without a significant increase in the risk of relapse. The effectiveness of induction therapy among patients with DS treated according to ALL-MB 2008 versus children with DS-ALL treated according to ALL-MB 2015 was 80 % versus 92 % respectively (p = 0.018). The probability of achieving continuous complete remission was also lower in the ALL-MB 2008 group compared to ALL-MB 2015 – 57 % versus 75 %; p < 0.001 respectively. Thus, the results of treatment of DS-ALL according to the ALL-MB 2015 protocol were better than those according to the ALL-MB 2008.Conclusion. The results of therapy for patients with DS-ALL are still unsatisfactory today, this circumstance dictates the need for new approaches to optimize therapy. The main problem for these patients remains the high toxicity of therapy and the associated lethality. Further progress in the treatment of DS-ALL may be associated with the development of new approaches to concomitant therapy, the use of molecular-targeted drugs and immunotherapy, as well as with the study of the molecular genetic characteristics of this subgroup of patients.