Drug levels, anti-drug antibodies and B-cell counts were not predictive of response in rheumatoid arthritis patients on low dose rituximab

Should complete B cell depletion be maintained in patients treated long-term with rituximab for rheumatoid arthritis?

OBJECTIVE

To determine whether persistent complete B cell (BC) depletion was associated with a better clinical response in rheumatoid arthritis (RA) patients long-term treated with rituximab (RTX).

METHODS

We conducted a retrospective study including RA patients admitted for a new infusion between 2019 and 2021. The primary endpoint was the comparison of the mean disease activity score based on 28 joints (DAS28)-CRP at each of the four last infusion visits between patients with persistent complete BC depletion (mean CD19 counts <18/µl at each of the last four visits) or without persistent complete BC depletion (mean CD19 counts of the last four visits ≥18/µl). Secondary endpoints included DAS28, pain/fatigue visual analogue scale, CRP, gammaglobulins and the frequency of self-reported RA flares.

RESULTS

Of the 126 patients in maintenance therapy with RTX [exposure period: 76 (5) months, 14 (7) infusions received], 43 (34%) had persistent complete BC depletion at each of the four last infusions. The mean DAS28-CRP calculated at each of the four last infusion visits did not significantly differ according to persistence or not of complete BC depletion. This result remained unchanged after adjusting for antibody status, number of previous therapies, number of RTX infusion and cumulative RTX dose. All secondary outcomes were also not significantly different between the two groups.

CONCLUSION

Maintaining complete BC depletion does not appear to be a therapeutic target to achieve in RA patients in long-term maintenance therapy with RTX. There is a limited benefit of monitoring CD19 in RA patients long-term treated with RTX and having achieved low disease activity/remission.

Patients' and rheumatologists' perceptions on dose reduction of rituximab in rheumatoid arthritis

OBJECTIVE

The recommended dose of a rituximab course for the treatment of Rheumatoid Arthritis (RA) consists of two infusions of 1000 mg with a 2-week interval. Evidence is growing that a lower dose could be as effective. We aimed to investigate patients' and rheumatologists' perceptions on dose reduction of rituximab.

METHODS

Patients with RA treated with rituximab, and rheumatologists were invited for a qualitative study via individual semi-structured interviews. Participants were recruited based on purposive sampling to ensure diversity. Interviews were analysed according to the principles of grounded theory and the constant comparative method.

RESULTS

Sixteen patients and 13 rheumatologists were interviewed. Patients and rheumatologists perceived the benefits of rituximab dose reduction for reasons of safety and societal costs. Furthermore, available evidence for the effectiveness of lower doses was mentioned as an argument in favour, in addition to the possibility to tailor the dose based on the patients' clinical manifestations. However, patients and rheumatologists had concerns about the potential loss of effectiveness and quality of life. Moreover, some rheumatologists felt uncomfortable with dose reduction due to insufficient experience with rituximab in general. Patients and rheumatologists emphasised the importance of shared decision-making, underscoring the pivotal role of physicians in this process by explaining the reasoning behind dose reduction.

CONCLUSION

Although some concerns on effectiveness were perceived, both patients and rheumatologists saw potential benefits of dose reduction in terms of safety, societal costs, and application of a personalised approach. As a result, most rheumatologists and patients showed a willingness to consider dose reduction strategies.

Infection incidence, timing and dose dependency in rheumatoid arthritis patients treated with rituximab: a retrospective cohort study

OBJECTIVES

Rituximab (RTX) is a safe and effective treatment for RA. However, there are some concerns about infection risk and preliminary data suggest dose and time dependency. This study aims to determine the infection incidence in a large real-life population of RA patients using RTX, with special focus on (ultra-)low dosing and time since last infusion.

METHODS

RA patients treated with 1000, 500 or 200 mg RTX per cycle between 2012 and 2021 at the Sint Maartenskliniek were included in a retrospective cohort study. Patient-, disease-, treatment- and infection characteristics were retrieved from electronic health records. Infection incidence rates, dose and time relations with RTX infusion were analysed using mixed-effects Poisson regression.

RESULTS

Among 490 patients, we identified 819 infections in 1254 patient years. Most infections were mild and respiratory tract infections were most common. Infection incidence rates were 41, 54 and 71 per 100 patient years for doses of 200, 500 and 1000 mg. Incidence rate ratio (IRR) was significantly lower for 200 mg compared with 1000 mg (adjusted IRR 0.35, 95% CI 0.17, 0.72, P = 0.004). In patients receiving 1000 or 500 mg RTX, infections seemed to occur more frequently within the first two months after infusion compared with later on in the treatment cycle, suggesting an association with peak concentration.

CONCLUSION

Ultra-low dosing (200 mg) of RTX is associated with a lower risk of infections in RA. Future interventions focusing on ultra-low dosing and slow release of RTX (e.g. by subcutaneous administration) may lower infection risk.

Identification of Covariates Modulating B-Cell Repopulation Kinetics in Subjects Receiving Rituximab Treatment

OBJECTIVE

B-cell depletion using the anti-CD20 monoclonal antibody rituximab is a cornerstone in the therapeutic concept of multiple autoimmune diseases. B-cell depletion is associated with a higher risk for severe infections, and the time span of B-cell repopulation differs greatly between individuals. Data on factors influencing B-cell repopulation kinetics are limited. This study aims to identify patient-specific and therapy-associated covariates that modulate B-cell repopulation.

METHODS

This single-center retrospective observational study presents data of 839 subjects receiving 2,017 courses of rituximab for autoimmune diseases. Assessed covariates are patient-specific factors (sex, age, kidney function, and underlying disease) and co-immunosuppression with common agents (azathioprine, cyclosporine A, cyclophosphamide, hydroxychloroquine, methotrexate, mycophenolate mofetil, tacrolimus, and corticosteroids). The primary end point is the time to B-cell repopulation (≥5/μl). The secondary end point is the time to B-cell reconstitution (≥50/μl). Multivariate time-to-event analysis and logistic regression models were applied to estimate the influence of covariates.

RESULTS

Age over 60 years (hazard ratio [HR] 0.71 for repopulation, P = 0.008), impaired kidney function (HR 0.72, P = 0.001), antineutrophil cytoplasmic antibody-associated vasculitis (HR 0.61, P < 0.001), solid organ transplantation (HR 0.4, P < 0.001), and co-immunosuppression with corticosteroids (HR 0.64, P < 0.001) or azathioprine (HR 0.49, P < 0.001) were associated with impaired B-cell repopulation and reconstitution. Effects of corticosteroids (P = 0.043) and azathioprine (P = 0.025) were dose dependent.

CONCLUSION

Prolonged rituximab dosing intervals may be effective to achieve B-cell depletion and reduce risk of infection in advanced age or patients with impaired kidney function. Co-medication with corticosteroids or azathioprine prolongs B-cell recovery, which may increase therapeutic effects but also the rate of adverse events.

Low dose versus standard dose rituximab for the treatment of antiphospholipid syndrome: A pilot study from a tertiary medical center

BACKGROUND

To investigate the therapeutic effects and safety of low-dose and standard-dose rituximab (RTX) in the treatment of antiphospholipid syndrome (APS).

METHODS

In this real-world study, we included 22 consecutive patients with APS who received RTX. Standard dose (SD) was defined as an overall dosage of RTX ≥ 1000mg in the induction period, and low dose (LD) was defined as an overall dosage of RTX <1000mg.

RESULTS

Of included patients, 1 patients died, 2 patients withdrew and 19 patients completed 6-month follow-up. Nine patients received SD-RTX and 13 patients received LD-RTX, and elder patients [LD-RTX vs. SD-RTX: (49.1 ± 15.5) vs. (35.8 ± 12.3) years, p = 0.044] and patients with later-onset [LD-RTX vs. SD-RTX: (46.8 ± 16.3) vs. (31.3 ± 13.6) years, p = 0.029] were more frequently included in LD-RTX than SD-RTX. Following 6 month RTX treatment, 8 patients (42.1%) achieved complete remission, 8 patients (42.1%) achieved partial remission and 3 patients (15.8%) showed no remission. The titers of anticardiolipin antibodies [baseline vs. 6 months: 30.8 (10.7, 90) vs. 19.5 (2.45, 69.10) U/L, p = 0.023] and the levels of erythrocyte sedimentation rate [baseline vs. 6 months: 29 (6, 63) vs. '6 (3, 14) mm/h, p = 0.021] exhibited a significantly decrease in all APS patients. Remission rate and titers of anti-β2-glycoprotein I and lupus anticoagulant did not differ significantly between two groups.

CONCLUSION

RTX might be a safe and effective option for patients with APS, and low dose confers equal efficacy as standard dose. Further cohort studies are needed to confirm our findings.

Seroconversion after a third COVID-19 vaccine is affected by rituximab dose but persistence is not in patients with rheumatoid arthritis

Objectives

In patients with rheumatoid arthritis (RA) treated with (ultra-)low dose rituximab (RTX), we investigated (1) the association of dosing and timing of rituximab (RTX) on seroconversion after third COVID-19 vaccination, and (2) persistence of humoral response after two-dose vaccination.

Methods

In this monocentre observational study, patients from the COVAC-cohort were included in the third vaccine analysis if humoral response was obtained 2-6 weeks after third vaccination in previous non-responders, and in the persistence analysis if a follow-up humoral response was obtained before third vaccination in previous responders. Dichotomization between ‘positive’ and ‘negative’ response was based on the assay cut-off. The association between latest RTX dose before first vaccination, timing between latest rituximab and vaccination, and response was analysed with univariable logistic regression.

Results

Of the 196 patients in the cohort, 98 were included in the third vaccine analysis and 23 in the persistence analysis. Third vaccination response was 19/98 (19%) and higher for 200 mg RTX users (5/13, 38%) than 500 and 1000 mg (7/37, 19% and 7/48, 15%). Non-significant trends were seen for higher response with lower dosing (200 versus 1000 mg: OR 3.66, 95% CI 0.93-14.0) and later timing (per month since infusion: OR 1.16, 0.97-1.35). Humoral response persisted in 96% (22/23) and in 89% (8/9) of patients who received RTX between the two measurements.

Conclusion

Repeated vaccination as late as possible after the lowest RTX dose possible seems the best vaccination strategy. A once positive humoral response after COVID-19 vaccination persists irrespective of intercurrent rituximab infusion.

Trial registration

Netherlands Trial Register, https://www.trialregister.nl/, NL9342