LAUSR

Background Mogamulizumab (Moga) is a C—C chemokine receptor-4 antibody approved in the United States for relapsed /refractory mycosis fungoides and Sézary syndrome. Few cases reported an increased risk of hepatitis B reactivation and cytomegalovirus (CMV) related infection post-Moga. However, literature is limited to mainly case reports and series, while no study has used the Food and Drug Administration adverse events reporting system (FARES) database to investigate the relationship. Methods Using United States Food and Drug Administration adverse events reporting system database, we collected all cases of hepatitis B reactivation and CMV related infection between January 1, 2011, and December 31, 2019, for Moga and other drugs. The reporting odds ratio (ROR) was calculated, which was considered significant when the lower limit of 95% confidence interval (CI) >1. Findings Three hundred and thirty-eight total adverse cases were reported for Moga during the study period, with 261 cases reported indication for use, including cutaneous T cell lymphoma (47.04%), and adult T cell leukemia/lymphoma (30.18%). Eight cases were reported for hepatitis B reactivation with Moga use, compared to 2290 cases with other medications. The ROR is 143.67 (p<0.001, 95% CI, 71.17–290.04). CMV related infection was noted in 17 cases using Moga, while 12,849 cases with others. The ROR is 55.89 (p<0.001, 95% CI, 34.31–91.06). In the Moga group, five deaths occurred in hepatitis B reactivation patients and nine deaths with CMV cases. Interpretation A signal has been identified between Moga exposure and hepatitis B reactivation as well as CMV related infection. A consideration in future studies should be placed on determining the relationship and investigating the need for pre-treatment screening, close monitoring, and utilization of prophylaxis in this population-based on pre-treatment risks. Funding None.