Pre-existing and treatment-emergent autoimmune cytopenias in patients with CLL treated with targeted drugs

Autoimmune cytopenias (AIC) affect 5-9% of patients with chronic lymphocytic leukemia (CLL). Targeted drugs - ibrutinib, idelalisib and venetoclax - have a prominent role in the treatment of CLL, but their impact on CLL-associated AIC is largely unknown. In this study, we evaluated the characteristics and outcome of pre-existing AIC, and described the incidence, quality and management of treatment-emergent AIC during therapy with targeted drugs in patients with CLL. We collected data from 572 patients treated with ibrutinib (9% in combination with an anti-CD20 monoclonal antibody), 143 treated with idelalisib-rituximab and 100 treated with venetoclax (12% in combination with an anti-CD20 monoclonal antibody). A history of pre-existing AIC was reported in 104/815 patients (13%). Interestingly, 80% of patients whose AIC was not resolved at the time of targeted drug start experienced an improvement or a resolution during therapy. Treatment-emergent AIC occurred in 1% of patients during ibrutinib therapy, in 0.9% during idelalisib and in 7% during venetoclax, with an estimated incidence rate of 5, 6 and 69 episodes per 1000 patients per year of exposure in the three treatment groups, respectively. The vast majority of patients who developed treatment-emergent AIC carried unfavorable biological features such as an unmutated IGHV, and a del(17p) and/or TP53 mutation. Notably, despite AIC, 83% of patients were able to continue the targeted drug, in some cases in combination with additional immunosuppressive agents. Overall, treatment with ibrutinib, idelalisib and venetoclax appears to have a beneficial impact on CLL-associated AIC, inducing an improvement or even a resolution of pre-existing AIC in most cases and eliciting treatment-emergent AIC in a negligible portion of patients.