Long-term clinical and radiological effectiveness and safety of ultralow doses of rituximab in rheumatoid arthritis: observational extension of the REDO trial.

BACKGROUND: The REDO trial (REtreatment with Rituximab in RhEmatoid arthritis: Disease Outcome after Dose Optimisation) showed similar disease activity for retreatment with ultralow doses (200 mg and 500 mg per 6 months) compared with standard low-dose rituximab (RTX, 1000 mg per 6 months). We performed an observational extension study of the REDO trial to assess long-term effectiveness. METHODS: Patients from the REDO trial were followed from start of the trial to censoring in April 2021. RTX use was at the discretion of patient and rheumatologist using treat to target. The primary outcome was disease activity (disease activity score in 28 joints C-reactive protein (DAS28-CRP)), analysed using a longitudinal mixed model by original randomisation and time-varying RTX dose. The original DAS28-CRP non-inferiority (NI) margin of 0.6 was used. RTX dose and persistence, safety and radiological outcomes were also assessed. FINDINGS: Data from 126 of 142 REDO patients was collected from 15 December 2016, up to 30 April 2021. Drop-outs continued treatment elsewhere (n=3) or did not consent (n=13).Disease activity did not differ by original randomisation group: 1000 mg mean DAS28-CRP (95% CI) of 2.2 (2.0 to 2.5), 500 mg 2.3 (2.1 to 2.4) and 200 mg 2.4 (2.2 to 2.5). Lower time-varying RTX dose was associated with higher DAS28-CRP (0.22 (95% CI 0.05 to 0.40) higher for 200 mg/6 months compared with 1000 mg/6 months), but remained within the NI-margin. RTX persistence was 93%. Median RTX dose was 978 mg (IQR 684-1413) per year, and no association was found between RTX dose and adverse events or radiological damage. INTERPRETATION: Long-term use of ultralow doses of RTX is effective in patients with rheumatoid arthritis responding to standard dose RTX.

Rituximab dose-dependent infection risk in rheumatoid arthritis is not mediated through circulating immunoglobulins, neutrophils or B cells.

OBJECTIVES: Rituximab (RTX) is a safe and effective treatment for RA. A dose-dependent infection risk was found in the REDO trial. Some studies associate RTX use with higher infection risks, possibly explained by low immunoglobulin levels and/or neutropenia. Additionally, a higher infection risk shortly after RTX infusion is reported. The objectives of this study were (i) to compare incidence rates of infections between doses and over time, and (ii) to assess B-cell counts, immunoglobulin levels, neutrophil counts and corticosteroid/disease modifying rheumatic drug use as mediating factors between RTX study dose and infection risk. METHODS: Post hoc analyses of the REDO trial were performed. Infection incidence rates between RTX dosing groups and between time periods were compared using Poisson regression. A step-wise mediation analysis was performed to investigate if any of the factors mentioned above act as a mediator in the observed dose-dependent difference in infection risk. RESULTS: The potential mediators that were investigated (circulating B-cell counts, immunoglobulin levels, neutrophil counts and drug use) did not explain the dose-dependent infection risk observed in the REDO trial. Additionally, a trend towards a time-dependent infection risk was found, with higher infection rates shortly after RTX infusion. CONCLUSIONS: These secondary analyses of the REDO trial confirmed the observed dose-dependent infection risk. Additionally, we found that infection risks were higher shortly after RTX infusion. However, a mediating pathway was not found.

Efficacious transition from reference infliximab to biosimilar infliximab in clinical practice.

OBJECTIVES: To evaluate the transition from reference infliximab Remicade to biosimilar Remsima in patients with rheumatoid arthritis (RA) or psoriatic arthritis (PsA). METHODS: Patients were informed through a letter about the transition to a biosimilar and were subsequently contacted for possible additional questions and whether they agreed upon the transition. Once agreed, Remsima was administered at the same dosage and interval as previous treatment with Remicade. Data on the transition were analyzed in January 2018. The primary outcome was the percentage of patients continuing treatment with Remsima and secondary outcome was the change in disease activity measured with the Disease Activity Score in 28 joints using erythrocyte sedimentation rate (DAS28-ESR). In addition, the reasons for discontinuation with infliximab or restarting Remicade were recorded. RESULTS: In total 47 patients were approached, 45 patients switched from Remicade to Remsima, two patients disagreed upon transition and continued Remicade. At the end of the follow-up period of 2 years, 39 patients (87%) continued with Remsima, three patients (7%) restarted Remicade due to inefficacy according to the patient (this was not objectified by the rheumatologist) 2 (4%) patients switched to another biological due to lack of effect and in one patient (2%) infliximab was stopped because of lung malignancy. Furthermore, the DAS28-ESR remained comparable before and after the switch, with a mean (SD) of 2.34 (±1.02) and 2.31 (±1.11) respectively. CONCLUSION: In our population, 87% of patients continued Remsima during the follow-up period of approximately 2 years. Three patients restarted Remicade, while retaining stable DAS28-ESR.

Ultra-low doses of rituximab for continued treatment of rheumatoid arthritis (REDO study): a randomised controlled non-inferiority trial.

BACKGROUND: Rituximab is an effective treatment for rheumatoid arthritis, given as either two doses of 1000 mg (2 weeks apart) every 6 months (the dose recommended by the US Food and Drug Administration and European Medicines Agency) or two doses of 500 mg (2 weeks apart) or one dose of 1000 mg (a standard low dose) every 6 months. Findings of several small uncontrolled studies suggest that doses lower than the recommended dose or standard low dose might be sufficient for maintenance treatment, potentially improving safety and reducing costs. Therefore, we aimed to compare the efficacy of ultra-low doses of rituximab (one dose of 500 mg or 200 mg) with a standard low dose of rituximab (one dose of 1000 mg) for patients with rheumatoid arthritis who respond to standard doses of rituximab. METHODS: The REDO study is a randomised, double-blind, non-inferiority trial done at five centres in the Netherlands. Adults (aged ≥18 years) with rheumatoid arthritis responding well to rituximab were randomly allocated (1:2:2) to receive intravenous rituximab as one dose of either 1000 mg, 500 mg, or 200 mg, respectively. Volumes of all doses were equal to achieve masking. Randomisation lists were computer-generated and stratified by rheumatoid factor or anti-citrullinated protein antibody status (positive or negative) and concomitant use of conventional synthetic disease modifying antirheumatic drugs (yes or no). The primary analysis was a per-protocol hierarchical testing procedure comparing ultra-low doses with a standard low dose (500 mg vs 1000 mg at 3 months, followed by 500 mg vs 1000 mg at 6 months, 200 mg vs 1000 mg at 3 months, and 200 mg vs 1000 mg at 6 months), using a non-inferiority margin of 0·60 on change from baseline in the 28-joint disease activity score based on C-reactive protein levels (DAS28-CRP). The study is registered at www.trialregister.nl, NTR6117. FINDINGS: Between Dec 15, 2016, and Sept 20, 2018, 142 patients were randomly allocated to either 1000 mg rituximab (n=29), 500 mg rituximab (n=58), or 200 mg rituximab (n=55). The 500 mg dose was non-inferior to 1000 mg at 3 months (mean change from baseline in DAS28-CRP, -0·07, 95% CI -0·41 to 0·27) but not at 6 months (0·29, -0·08 to 0·65). Because of the hierarchical testing procedure, non-inferiority could not be tested for the 200 mg dose. 13 patients had serious adverse events, three (10%) in the 1000 mg group, six (10%) in the 500 mg group, and four (7%) in the 200 mg group. The most frequently reported serious adverse events were cardiovascular. No deaths occurred during the study. A significantly lower incidence of infections was seen in the ultra-low-dose groups compared with the standard dose group (1·10 infections per patient-year with the 1000 mg dose vs 0·52 per patient-year with the 500 mg dose and 0·51 per patient-year with the 200 mg dose; rate ratio 0·47, 95% CI 0·21-0·83; p=0·013 for 500 mg vs 1000 mg; 0·44, 0·22-0·88; p=0·019 for 200 mg vs 1000 mg). INTERPRETATION: Our study did not show non-inferiority of ultra-low doses of rituximab for continued treatment of patients with rheumatoid arthritis. Nonetheless, in clinical practice, a strategy with an ultra-low dose of rituximab might be considered after evaluation of risks and benefits, although further studies are needed to establish non-inferiority. Further analyses and a 2-year observational extension are ongoing and should provide further insight into efficacy and safety. FUNDING: Menzis and Centraal Ziekenfonds.

Myocardial infarction after rituximab treatment for rheumatoid arthritis: Is there a link?

Rituximab is an anti-CD20 monoclonal antibody often used in the treatment of rheumatoid arthritis (RA). Infusion reactions sometimes develop following rituximab administration. Delayed complications are rare. Acute coronary syndromes are listed as sideeffects of rituximab therapy. We report two cases of acute myocardial infarction following rituximab therapy for RA and review the literature regarding cardiac events in patients treated with rituximab. We would like to raise awareness of this possible complication in patients treated with rituximab.