Long‐term immune changes in patients with relapsed/refractory chronic lymphocytic leukemia following treatment with venetoclax plus rituximab

Abstract

Abstract Immune dysregulation is a hallmark of chronic lymphocytic leukemia (CLL). Anti‐CD20 antibodies (e.g., rituximab [R]) can be combined with venetoclax (Ven) to treat CLL. However, anti‐CD20 antibodies can increase hypogammaglobulinemia risk, while the effects of Ven on immune dysregulation are still uncertain. We report long‐term immune changes in VenR‐ and bendamustine‐R (BR)‐treated patients with relapsed/refractory CLL in the MURANO trial (NCT02005471). Patients were randomized to fixed‐duration VenR (2 years Ven; VenR for the first 6 months) or BR (6 months). Immune cell levels were evaluated at the end of combination treatment (EOCT), end of treatment (EOT; VenR arm only), and 12 and 24 months post‐EOCT. Overall, 130/194 VenR‐ and 134/195 BR‐treated patients completed treatment without progressive disease. In patients who completed VenR combination therapy, median immunoglobulin (Ig)G and IgM levels decreased from baseline to EOT (p ≤ 0.01 and p ≤ 0.0001, respectively); by 24 months, post‐EOT IgG had returned to baseline level and IgM had increased from baseline (p ≤ 0.001). Median IgA levels increased from baseline to 12 (p ≤ 0.0001) and 24 months post‐EOT (p ≤ 0.0001). In BR‐treated patients, changes in IgG, IgA, and IgM levels across the assessed time points were not significant, and by 24 months, post‐EOCT IgG, IgA, and IgM were above baseline levels. Grade ≥3 infection rates on treatment were low. Overall, immune recovery was observed with VenR and BR, with stabilization of Ig levels after treatment. Post‐treatment infection rates were generally low, making these very tolerable therapies for CLL.