Risk of Serious Adverse Events, Infection and Sepsis in Patients with Relapsed and Refractory Chronic Lymphocytic Leukemia/ Small Lymphocytic Lymphoma Treated with Idelalisib

Introduction:

Idelalisib is a first-in-class potent, oral, selective small-molecule inhibitor of δ isoform of phosphatidylinositol 3-kinase (PI3Kδ), which involves in the signaling of B-cell receptor pathways via activation of downstream serine threonine kinases AKT and mammalian target of rapamycin (mTOR), and has been implicated in the pathogenesis of chronic lymphocytic leukemia/ small lymphocytic lymphoma (CLL/SLL). Yet, there are considerable safety concerns. We undertook a systematic review and combined analysis of phase 3 randomized controlled trials to determine the risk of serious adverse events, infection and sepsis in patients with relapsed/ refractory CLL/SLL treated with idelalisib.

Methods:

We systematically conducted a comprehensive literature search using MEDLINE, EMBASE databases and meeting abstracts from inception through June 2019. Phase 3 RCTs utilizing idelalisib in patients with relapsed and refractory CLL/SLL that mention serious adverse events, infection and sepsis as adverse effects were incorporated in the analysis. Mantel-Haenszel (MH) method was used to calculate the estimated pooled risk ratio (RR) with 95% confidence interval (CI). Heterogeneity was assessed with Cochran's Q- statistic. Random effects model was applied.

Results:

Three phase 3 RCTs with a total of 892 patients with relapsed and refractory CLL/SLL were eligible for analysis. Studies compared ofatumumab vs idelalisib+ofatumumab, rituximab vs idelalisib+rituximab, bendamustine+ rituximab vs idelalisib+bendamustine+rituximab and ofatumumab vs duvelisib. The randomization ratio was 2:1 in Jones et al. study and 1:1 in other studies. The I² statistic for heterogeneity was 83, suggesting moderate heterogeneity among RCTs. The incidence of serious adverse events was 341 (69.59%) in study group vs 177 (44.03%) in control group with RR of 1.50 (95% CI: 1.28-1.75; p < 0.0001). Pneumonitis was noted in 14 (2.86%) vs 1 (0.25%) in control group (RR, 5.42; 95% CI: 1.22-24.13; p = 0.03). The incidence of any-grade pneumonia was 78 (15.92%) in study group vs 45 (11.19%) in control group (RR, 1.38; 95% CI: 0.98 - 1.96; P = 0.07). High-grade pneumonia was reported in 59 (12.04%) in idelalisib arm versus 33 (8.21%) in control group with RR of 1.36 (95% CI: 0.82 - 2.27; P = 0.23). Pneumocystis jiroveci (PJP) pneumonia rate was 2.56% higher in study group compared to control arm (RR, 4.25; 95% CI: 1.10 - 16.34; P = 0.04). Febrile neutropenia was noted in 13.47% in study group versus 4.73% in control arm (RR, 2.39; 95% CI: 0.90-6.34; p = 0.08). Sepsis rate was 3.36% higher in idelalisib group compared to control arm and the pooled RR was statistically significant at 2.64 (95% CI 1.10-6.30; p = 0.03). Treatment-related deaths were 45 (6.92%) in idelalisib arm vs 21 (3.74%) in control arm according to analysis of 2 trials. The pooled RR was not statistically significant at 1.64 (95% CI: 0.99 -2.71; P = 0.06).

Conclusion:

Patients on idelalisib experienced higher risk of serious adverse events, pneumonitis, PJP pneumonia, and sepsis, with RR of 1.50 for serious adverse events, RR of 5.42 for pneumonitis, RR of 4.25 for PJP pneumonia and RR of 2.64 for sepsis respectively. Nevertheless, there was no significant increase in treatment-related deaths due to TRAE in the idelalisib group, compared to control arm. Preemptive measures with proper supportive care are required to reduce those toxicities which can ultimately improve patients' quality of life and may probably affect patients' compliance.