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In line with the current licensing indications, rituximab (RTX), a monoclonal anti-CD20 antibody1 can be administered solely in combination with methotrexate (MTX).2 However, some patients are ineligible for this treatment due to contraindications to or intolerance of MTX, resulting in an unmet need for alternative treatment protocols.
The aim of our study was to determine the efficacy, safety and kinetics of B cell depletion3 following a single course of RTX as a monotherapy.
In total, 40 patients with active rheumatoid arthritis (RA) were followed. Twenty patients received rituximab as a monotherapy having previously failed or been intolerant of MTX and other disease modifying antirheumatic drugs (study group). Twenty patients received MTX at a stable dose for at least 6 months before randomisation, and continued to receive it throughout the study (control group). A single course of RTX was administered.4 Concomitant medication was maintained stable through week 24.
The baseline characteristics of the patients are outlined in table 1.
At week 16, there was no significant difference in the mean DAS28 score between the study and control group (4.53 vs 4.43 respectively). Ten per cent of the patients in the study group achieved a good and 85% a moderate EULAR response,5 as compared with 15% and 70% in the control group.
The mean absolute CD19+ B cell counts at week 16 were similar in both groups. The percentage of patients with re-population of CD19+ B cells at week 24 was slightly higher in the study group (20 vs 13%).
Patients in this group had a significantly higher number of previous anti-TNFs. A subanalysis within this arm comparing subjects with no previous exposure to TNF inhibitors to those receiving ⩾1 previous TNF blockers revealed no significant differences in the response rates (ΔDAS28: 1.78 vs 1.4). Similarly, there was no statistically significant difference in the response rates between rheumatoid factor positive and negative patients (ΔDAS28: 1.57 vs 1.55).
Acute infusion reactions were reported in two patients without and in three with concomitant MTX treatment. Two infections occurred in the former group (bronchitis and pneumonia) and one in the latter (neutropenia with septicaemia, which required hospitalisation). All events resolved without sequelae.
In summary, we demonstrated that rituximab is effective in patients with active RA in whom treatment with MTX is precluded due to intolerance or contraindications. In our study, RTX monotherapy resulted in good or moderate EULAR responses in the majority of patients. Furthermore, the lack of concomitant MTX did not affect the degree of B cell depletion nor the kinetics of B cell re-population, although there was a trend suggesting an earlier re-population in monotherapy patients.
Our data are in concordance with the study by Edwards et al, wherein neither the DAS28 score at week 24 nor the percentages of patients achieving a good-to-moderate EULAR response varied significantly between RTX arms.6 However, the percentages of patients achieving American College of Rheumatology criteria (ie, ACR50 and ACR70) responses or maintaining the response beyond week 48 were higher with concomitant MTX; this implies that this combination should be preferred in patients tolerating MTX.
Competing interests: None.
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