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Rituximab efficacious in patients with inadequate response to TNF inhibitors in repeated courses

Wednesday, December 12 2007 | Comments

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What's This? Repeated courses of rituximab appear to produce sustained efficacy among patients with active rheumatoid arthritis who have had an inadequate response to tumor necrosis factor inhibitors, according to Dr. Edward Keystone, a professor of rheumatology at the University of Toronto.

Dr. Keystone presented updated interim efficacy data from an ongoing, open-label extension study designed to evaluate the long-term efficacy of repeated courses of rituximab, a selective B cell targeted therapy, in patients who had experienced toxicity or had an inadequate response to >=1 TNF inhibitors, >=1 disease-modifying antirheumatic drugs, and methotrexate.

Patients who received 1 course of rituximab treatment in Phase II and Phase III trials were eligible for the extension study. The current analysis was based on data from 97 patients who had completed 3 courses of rituximab therapy and had >=24 weeks of follow-up after the third course. Each course of treatment consisted of 2 infusions of rituximab 2 weeks apart in addition to premedication with glucocorticoids and steroids. The patients also continued to receive methotrexate.

The median time between treatment courses was 37.9 weeks between courses 1 and 2 and 42.1 weeks between courses 2 and 3.

The primary efficacy assessments were the changes from baseline of the original studies to 24 weeks after the start of each treatment course in American College of Rheumatology (ACR) response, European League Against Rheumatism (EULAR) response, and 28-item Disease Activity Scores (DAS28).

From the first to the second course, there was an increase in the rate of ACR 20, ACR 50, and ACR 70 responses. From the second to third course, ACR 20, ACR 50 responses were relatively stable, and ACR 70 responses increased.

Specifically, 69% of the patients had achieved an ACR 20 response 24 weeks after course 1, 76% had done so after course 2, and 77% had done so after course 3. Further, 36% of the patients had achieved an ACR 50 response 24 weeks after course 1 and 48% of the patients had done so after courses 2 and 3; 11% of the patients had achieved an ACR 70 response 24 weeks after course 1, 19% had done so after course 2, and 25% had done so after course 3.

Relative to the baseline for each course, there was stability in ACR 20 and ACR 50 responses and an increase in ACR 70 responses.

By the second and third courses, approximately 90% of the patients had a moderate/good EULAR response, and 29% of the patients had a good EULAR response by course 3.

Based on DAS28, the percentage of patients with low disease activity increased from course 1 (11%) to course 2 (26%) and was steady for course 3 (29%). The respective percentages of patients who met DAS28 remission criteria after each course were 6%, 14%, and 12%.

The mean change in DAS28 from the original baseline was -2.39 for course 1, -2.94 for course 2, and -3.10 for course 3.

"[R]epeat courses of rituximab in patients with active RA who have an inadequate response to a TNF inhibitor have a sustained outcome, or at least certainly a sustained response, relative to the original baseline," Dr. Keystone concluded. (Abstract 2088.)

This information concerns a use that has not been approved by the Food and Drug Administration.

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