Ultra-Low Dose Rituximab for RA Correlated With Reduced Infection Risk

Treatment with ultra-low dose rituximab (RTX) for rheumatoid arthritis (RA) is associated with reduced infection risk. Future interventions, such as subcutaneous administration with slow-release RTX, could further lower the risk for infection, according to study results published in Rheumatology (Oxford).

Researchers conducted a retrospective cohort study including a large, real-life population of patients with RA treated with ultra-low-dose RTX. They analyzed the incidence rates (IRs) of infections and the relationship between dose and time of RTX infusion as predictors of infection.

Patients with RA received different doses of RTX (1000 mg, 500 mg, or 200 mg per cycle) between 2012 and 2021. They were monitored from the time of inclusion until February 2022 or until they were lost to follow-up, switched to another biologic or targeted synthetic disease-modifying antirheumatic drug, reported RTX treatment interruption, or received another immunosuppressive treatment.

A total of 490 patients met the inclusion criteria and were enrolled in the study, resulting in a cumulative follow-up of 1254 patient-years (PYs; median follow-up, 2 years).

A total of 819 cases of infection were reported, with IRs of 65 and 7.4 per 100 PYs for overall infections and serious infections, respectively. The majority of infections were mild, with respiratory tract infections being the most prevalent.

The infection risk was observed to be much lower among patients with RA who received treatment with ultra-low dose (200 mg) RTX compared with the standard low-dose of 1000 mg (adjusted incidence rate ratio, 0.35; 95% CI, 0.17-0.72; P =.004).

The IR for overall infection was 72 per 100 PYs during the first 2 months following RTX initiation, 61 per 100 PYs from months 2 to 4, and 63 per 100 PYs from months 4 to 6. 

Patients who received either 1000 mg or 500 mg of RTX were associated with a higher incidence of infection during the initial 2 months following infusion compared with later in the treatment cycle. The investigators note this data suggests a possible correlation with peak concentration.

This study is limited by its retrospective design, which may have led to underestimation of infections due to underreporting by rheumatologists or patients’ self-recall. Additionally, sample sizes for certain types of infections may be underpowered and exact RTX infusion initiation dates were often missing.

“In conclusion, this study shows that treatment with ultralow RTX doses reduces overall infection risk in RA patients. This adds to other benefits which include better vaccination response as seen for SARS-CoV-2, reduced infusion time, and lower costs,” the study authors stated.

Disclosures: One or more study author declared affiliations with biotech, pharmaceutical, and/or device companies. Please see the original reference for a full list of disclosures.