Wearing-Off Effect Reports in People With Multiple Sclerosis Receiving Ocrelizumab

Background: A wearing-off effect has been reported in people with multiple sclerosis (MS) receiving ocrelizumab and other monoclonal antibodies. We sought to describe the real-world occurrence of wearing-off effect among people with MS in Canada treated with ocrelizumab. Methods: Canadian self-reports coded to the Medical Dictionary for Regulatory Activities preferred term therapeutic response shortened (which included reports using the terms wearing-off, crap gap, wore off, or end-of-cycle phenomenon) between November 5, 2008, and March 15, 2023, were identified from the Roche Global Safety Database. Cases were then linked to patient-level data from the Canadian Roche Patient Support Program (COMPASS). Only people with MS who had received 3 or more doses of ocrelizumab were included. Results: A total of 10,055 people with MS in Canada received 3 or more doses of ocrelizumab within COMPASS. Therapeutic response shortened was reported 140 times among 138 unique cases (1.3%) over an average of 7.4 infusions. Discontinuation of ocrelizumab was generally uncommon. In the overall COMPASS population, 11.4% (1143 of 10,055) discontinued ocrelizumab. Among those who reported therapeutic response shortened, 15.9% (22 of 138) discontinued while the majority (116 of 138; 84.1%) continued ocrelizumab treatment. Of individuals reporting the adverse event of interest, those with relapsing-remitting MS more frequently remained on therapy (98 of 112; 87.5%) compared with those with primary progressive MS (18 of 26; 69.2%). Conclusions: A wearing-off effect was infrequently reported and was not treatment limiting among people with MS in the real-world COMPASS patient support program.