CLO19-025: Treatment Discontinuation Due to Adverse Events and the Risk of Gastrointestinal Toxicities in Patients With Hematologic Malignancies Treated With Ibrutinib

Abstract

Background: Ibrutinib targets Bruton’s tyrosine kinase, a kinase involved in signaling of B-cell and chemokine receptors, which are implicated in the pathogenesis of hematologic malignancies. Ibrutinib has been shown to improve survival in hematologic malignancies, and yet the tolerability has not been elucidated. We undertook systematic review and pooled analysis of randomized controlled trials (RTCs) to determine the risk of gastrointestinal toxicities and the rate of treatment discontinuation due to adverse events. Methods: We performed a comprehensive literature search using MEDLINE, EMBASE databases and meeting abstracts through September 2018. Phase 3 RCTs that mention gastrointestinal toxicities and the rate of treatment discontinuation due to adverse events were incorporated in the analysis. Mantel-Haenszel method was used to calculate the estimated pooled risk ratio with 95% CI. Random effects model was applied. Results: 6 phase III RCTs with a total of 1,811 patients with chronic lymphocytic leukemia/small lymphocytic lymphoma, mantle cell lymphoma, and Waldenstrom’s macroglobulinemia were included. Studies comparing ibrutinib vs ofatumumab, ibrutinib vs chlorambucil, ibrutinib + bendamustine + rituximab vs placebo + bendamustine + rituximab, ibrutinib vs temsirolimus, and ibrutinib vs rituximab were included in the analysis. The incidence of treatment discontinuation due to adverse events was 9.30% in the ibrutinib group vs 13.13% in the control arm. The relative risk (RR) for treatment discontinuation was 0.740 (95% CI: 0.385–1.423; P=.367). The pooled RR of all-grade side effects were as follows: diarrhea, 1.955 (95% CI: 1.304–2.933; P=.001); nausea, 1.038 (95% CI: 0.702–1.534; P=.852); vomiting, 1.048 (95% CI: 0.547–2.007; P=.888); and stomatitis, 1.262 (95% CI: 0.112–14.173; P=.850). The RR of high-grade adverse effects were as follows: diarrhea, 1.749 (95% CI: 0.866–3.530; P=.119); nausea, 2.237 (95% CI: 0.478–10.471; P=.306); vomiting, 0.429 (95% CI: 0.111–1.659; P=.220); and stomatitis, 0.309 (95% CI: 0.028–3.440; P=.340). Conclusion: Our study demonstrated that patients on ibrutinib arm noted increased risk of all-grade diarrhea. Nevertheless, other GI toxicities as well as treatment discontinuation due to adverse events were not statistically significant in the ibrutinib group compared with the control arm.