Kinase Inhibitors (ibrutinib or idelalisib) in the Management of Chronic Lymphocytic Leukemia-Associated Autoimmune Cytopenia: A Retrospective Study of the French Innovative Leukemia Organization (FILO)

Background

Autoimmune cytopenia (AIC) are well-known complications of chronic lymphocytic leukemia, occurring in approximately 4 to 10% of patients. The management of CLL-associated AIC is not consensual and patient with uncontrolled AIC are systematically excluded from clinical trials. Few data evaluating the efficacy of BCR inhibitors on CLL-related AIC are available. If some preliminary data focusing on patients included in clinical trials with controlled AIC suggested that ibrutinib was able to control AIC, the duration of responses were unknown. Moreover, no data regarding the ability of idelalisib to control AIC have been currently reported. The aim of this study was to retrospectively analyze the outcome of CLL patients suffering from autoimmune hemolytic anemia (AIHA), immune thrombocytopenia (ITP), Evans syndrome or pure red cell anemia (PRCA) and treated with ibrutinib or idelalisib.

Results

Forty-four patients from 15 FILO centers were included in this study. First kinase inhibitor (KI) was ibrutinib for 25 patients and idelalisib for 19 patients. Among the ibrutinib treated patients, diagnosis of AIC was AIHA for 16 patients (64%), ITP for 5 patients (20%), Evans syndrome for 3 patients (12%) and PRCA for one patient (4%). In the idelalisib group, 12 patients were treated for AIHA (63%), 6 patients for ITP (32%) and one patient for an Evans syndrome (5%). Most patients presented with adverse prognostic factors such as 11q or 17p deletion by FISH and unmutated IgHV. Most patients had previously been treated either for CLL progression, autoimmune cytopenia or both and median number of prior therapies was 1 (0 to 6). Before starting ibrutinib or idelalisib, 34 patients (77%) had a history of AIC and had previously received corticosteroid monotherapy (N=15), rituximab monotherapy (N=15), a combination of rituximab, cyclophosphamide and dexamethasone (N=23) or rituximab and bendamustine (N=15). At the time of KI initiation, 66% of patients were receiving concomitant AIC therapy, consisting in corticosteroids in 26 patients (59%) or TPO (thrombopoietin) receptor agonists in 3 patients (7%).

Overall response rates (ORRs) to ibrutinib and idelalisib on AIC were 92% and 95% respectively, and were not correlated to the AIC type. On ibrutinib therapy, 87.5% of patients with AIHA and 100% of patients with ITP or Evans syndrome achieved at least partial response (PR). In the idelalisib group, the ORR was 92% for AIHA patients and 100% for patients with ITP or PRCA. Considering CLL, Ibrutinib ORR and bone marrow unconfirmed complete response (CR) were 100% and 24% respectively. ORR and BM unconfirmed CR on CLL were 95% and 37% respectively the idelalisib group. KI therapy allowed discontinuing corticosteroids in 86% of ibrutinib patients and in 67% of idelalisib patients.

Fifteen patients (34%) of the whole cohort experienced progression of CLL, CAI or both during the follow-up. Among them, nine (20%) experienced relapses of the CAI, and all of them were AIHA. In the ibrutinib arm, 1 patient withdrew ibrutinib shortly after initiation because of uncontrolled AIHA and 2 patients experienced relapse of AIHA while on therapy. In the idelalisib group, treatment failed to control AIHA in one case, but for responding patients, no AIHA relapse was described during idelalisib treatment. Five patients experienced relapse of AIHA after idelalisib discontinuation. With a median follow-up of the entire cohort of 26.8 months, the estimated two years overall survival (2y-OS) of the whole cohort was 88%, while the estimated two years progression free survival (2y-PFS) were 75.3% for CLL and 65.1% for AIC. In the ibrutinib cohort, 2y-OS was 95% and 2y-PFS were 81% for AIC and 94.4% for CLL. In the idelalisib arm, 2y-OS was 80%. Median PFS was 19 months for AIC and 25.7 months for CLL.

Conclusion

Our results demonstrate that kinase inhibitors are able to induce long-term control of both AIC and CLL and represent new therapeutics options for patients with AIC associated with CLL.