Andrew R Melville1,2, Md Yuzaiful Md Yusof1,2, John Fitton1,2, Leticia Garcia-Montoya1,2, Lynda Bailey3, Shouvik Dass1,2, Paul Emery1,2, Maya H Buch1,4, Benazir Saleem3. 1. Leeds Institute of Rheumatic and Musculoskeletal Medicine, University of Leeds, Chapel Allerton Hospital, Leeds, UK. 2. NIHR Leeds Biomedical Research Centre, Leeds Teaching Hospitals NHS Trust, Leeds, UK. 3. Rheumatology Department, Leeds Teaching Hospitals NHS Trust, Leeds, UK. 4. Centre for Musculoskeletal Research, School of Biological Sciences, Faculty of Biology, Medicine & Health, University of Manchester, Manchester, UK.
Abstract
OBJECTIVE: To evaluate the impact of non-medical switch from rituximab originator (RTX-O) to biosimilar (RTX-B) in patients with RA. METHODS: Between October 2017 and October 2019, all patients on RTX-O in our centre requiring re-treatment were switched to RTX-B unless declined by the patient or specified by the treating clinician. Switch strategy effectiveness was assessed retrospectively using DAS28-CRP(3) and RTX retention, with patients remaining on RTX-O as a comparator group. RESULTS: The number of patients switching to RTX-B was 255/337 (75.7%) while 82 (24.3%) remained on RTX-O. There was no difference in DAS28-CRP(3) 4 months post-RTX-B switch vs the same time point post-RTX-O previous cycle (paired data available in 60%). Eighteen-month retention estimates were 75.6% (95% CI: 69.4, 80.7%) for RTX-B group and 82.3% (95% CI: 70.4, 89.8%) for RTX-O [adjusted hazard ratio 1.52 (95% CI: 0.85, 2.73)]. The number of patients who discontinued RTX-B for loss of effectiveness (LOE) was 42/255 (16.5%), five (2.0%) for adverse effects (AEs). Risk of RTX-B discontinuation was associated with comorbidities and ≥2 previous biologic DMARDs. Risk of adverse outcome RTX cessation was associated with comorbidities, and reduced risk with number of previous RTX-O cycles and pre-switch cycle B cell depletion. The number of patients who switched back to RTX-O was 34/255 (13.3%) (LOE: 30, AEs: 4), while 13/255 (5.1%) started other biologic/targeted synthetic DMARDs. Of patients who switched back for LOE, 28/30 remained on RTX-O at a mean 7.7 months follow-up. CONCLUSION: Non-medical switch to RTX-B was largely effective. Factors associated with RTX-B discontinuation, including comorbidities, previous biologic DMARDs, and RTX-O treatment history, may inform switch decisions. Most patients who switched back to RTX-O for LOE remained on treatment at short-term follow-up.
OBJECTIVE: To evaluate the impact of non-medical switch from rituximab originator (RTX-O) to biosimilar (RTX-B) in patients with RA. METHODS: Between October 2017 and October 2019, all patients on RTX-O in our centre requiring re-treatment were switched to RTX-B unless declined by the patient or specified by the treating clinician. Switch strategy effectiveness was assessed retrospectively using DAS28-CRP(3) and RTX retention, with patients remaining on RTX-O as a comparator group. RESULTS: The number of patients switching to RTX-B was 255/337 (75.7%) while 82 (24.3%) remained on RTX-O. There was no difference in DAS28-CRP(3) 4 months post-RTX-B switch vs the same time point post-RTX-O previous cycle (paired data available in 60%). Eighteen-month retention estimates were 75.6% (95% CI: 69.4, 80.7%) for RTX-B group and 82.3% (95% CI: 70.4, 89.8%) for RTX-O [adjusted hazard ratio 1.52 (95% CI: 0.85, 2.73)]. The number of patients who discontinued RTX-B for loss of effectiveness (LOE) was 42/255 (16.5%), five (2.0%) for adverse effects (AEs). Risk of RTX-B discontinuation was associated with comorbidities and ≥2 previous biologic DMARDs. Risk of adverse outcome RTX cessation was associated with comorbidities, and reduced risk with number of previous RTX-O cycles and pre-switch cycle B cell depletion. The number of patients who switched back to RTX-O was 34/255 (13.3%) (LOE: 30, AEs: 4), while 13/255 (5.1%) started other biologic/targeted synthetic DMARDs. Of patients who switched back for LOE, 28/30 remained on RTX-O at a mean 7.7 months follow-up. CONCLUSION: Non-medical switch to RTX-B was largely effective. Factors associated with RTX-B discontinuation, including comorbidities, previous biologic DMARDs, and RTX-O treatment history, may inform switch decisions. Most patients who switched back to RTX-O for LOE remained on treatment at short-term follow-up.