Tracking Secondary Immune Deficiencies in Pediatric BCP-ALL Patients: A Prospective Study from Single Center

Introduction Leukemias are the most common pediatric neoplastic diseases, with approximately 80% classified as B cell precursor acute lymphoblastic leukemia (BCP-ALL). Its treatment often leads to secondary immunodeficiency. The LLA-GATLA-ALLIC2022 protocol includes assessment of the impact of immunotherapy targeting CD20 in patients with CD20+ blast at day (D)15. We describe the immune status of pediatric BCP-ALL patients throughout the course of their treatment. Methods Prospective study of 35 BCP-ALL patients [1-14 years] were evaluated, intra-induction/pre-rituximab (D22), preconsolidation (D78), and intra-maintenance (D360). Patients (p) were classified into two groups based on their randomization to receive rituximab (G1) (n = 5) or not (G2) (n = 30). Serum immunoglobulin levels, complete blood count, and lymphocyte subset counts were evaluated. ANOVA test was performed. Results At diagnosis, none of the patients exhibited hypogammaglobulinemia of any isotype. During treatment, both groups experienced reduction in IgG and IgM levels; however, patients in G1 showed significantly lower IgG and IgM levels at D78 (p < 0.001). At D22, 24/35p (69%) developed neutropenia (p < 0.001); G2, 0.04% (p < 0.001). G2 maintained a significant reduction in B lymphocyte (mean: 2.7%, p < 0.001) at D360. Natural killer cell mean counts (%) (D78: G1: 3.4; G2: 7.9, D360: G1: 7.8; G2: 6.5) remained low throughout the first year of treatment compared to D22. Conclusion This study serves as a crucial starting point, providing guidance for a wider patient cohort and establishing follow-up protocols to assess the immune status during BCP-ALL treatment. This will allow earlier detection of secondary deficiencies and the implementation of prophylaxis and specific treatments.