What is the success rate of Rituxan (rituximab) in rheumatoid arthritis?
Rituxan (rituximab) is a monoclonal antibody, which works by targeting the CD20 protein antigen displayed on the surface of B-cells. It is used in the treatment of rheumatoid arthritis and also for a number of other conditions including non-Hodgkin's lymphoma (NHL), chronic lymphocytic leukemia (CLL), granulomatosis with polyangiitis (GAP) and moderate to severe pemphigus.
Rituxan is used in combination with methotrexate in adults with moderately-to-severely-active rheumatoid arthritis who have inadequate response to one or more TNF (tumor necrosis factor) antagonist therapies.
Results from clinical trials show that treatment with Rituxan successfully improves patient outcomes including reducing symptoms, levels of fatigue and disability, and increasing health-related quality of life. It also slows the progression of structural damage in joints.
Rituxan plus methotrexate is better than methotrexate alone at improving symptoms
In clinical trials the ACR (American College of Rheumatology) response criteria measures how much a patient’s symptoms have improved between two set points in time. ACR20, ACR50 and ACR70 are commonly reported. Patients achieving ACR20, ACR50 and ACR70 show a ≥20%, ≥50% and ≥70% improvement in symptoms between the two set time points, respectively. The ACR criteria looks at the number of swollen and tender joints a patient has, c-reactive protein levels, erythrocyte sedimentation rates and other measures of pain, disability and disease activity.
Results from the phase III REFLEX (Randomized Evaluation of Long-Term Efficacy of Rituximab in RA) trial, showed that significantly more patients treated with Rituxan and methotrexate achieved ACR20 (51% vs 18%), ACR50 (27% va 5%) and ACR70 (12% vs 1%) compared with patients treated with placebo and methotrexate after 24 weeks of treatment (p<0.0001). Patients enrolled in the trial had active, longstanding rheumatoid arthritis and had had an inadequate response to treatment with an anti-TNF agent.
European League against Rheumatism (EULAR) response criteria also showed 65% of patients who received Rituxan plus methotrexate achieved a moderate-to-good EULAR response compared with 22% of patients who received placebo plus methotrexate (p<0.0001).
A separate phase III trial called SUNRISE, in which patients received a second course (re-treatment) of Rituxan, also showed Rituxan plus methotrexate to be better than placebo plus methotrexate.
Fatigue, disability and health-related quality of life improved by Rituxan treatment
The REFLEX trial also measured how effective Rituxan is using FACIT-F, HAQ DI and SF-36 scores. Results showed that treatment with Rituxan plus methotrexate was better than placebo plus methotrexate when it came to improving fatigue, disability and health-related quality of life.
- Rituxan-treated patients had a significant reduction in levels of fatigue as measured by the FACIT-F (Functional Assessment of Chronic Illness Therapy - Fatigue) scale. Their scores decreased by 9.1 points on average, representing a 29.6% improvement in their levels of fatigue, compared with only a 0.5 point decrease in patients who didn’t receive Rituxan.
- Six percent of Rituxan-treated patients had an HAQ DI score of 0 at 24 weeks, compared with 0.5% of patients who didn’t receive Rituxan. HAQ DI - the Health Assessment Questionnaire Disability Index - is a questionnaire used to determine a patient’s functional ability, including their ability to dress, eat, walk, reach, take care of themselves and more.
- Rituxan-treated patients had significant improvements in their mental and physical health, as measured by the SF-36, a 36-item short form survey. Mental and physical health domain scores increased by 4.7 and 5.8, respectively, in patients treated with Rituxan plus methotrexate, compared with increases of only 1.3 and 0.9, respectively, in patients who didn’t receive Rituxan (p=0.0002).
Rituxan plus methotrexate helps to slow the progression of structural damage in joints
An extension of the REFLEX trial has also shown that treatment with Rituxan helps to reduce the progression of structural damage in joints in patients with rheumatoid arthritis.
- No radiographic progression was observed in 60% of patients treated with Rituxan plus methotrexate at 1 year, compared with 46% of patients treated with placebo plus methotrexate.
- No radiographic progression was observed in 68% of patients treated with Rituxan plus methotrexate at 2 years, which was higher than the 60% figure reported after 1 year.
- Of the Rituxan-treated patients who had no progression in the first year, 87% continued to have no signs of progression of structural joint damage in their second year. When results for all patients were included, 57% had no radiographic progression at 2 years.
- Cohen SB, Emery P, Greenwald MW, et al. Rituximab for rheumatoid arthritis refractory to anti-tumor necrosis factor therapy: Results of a multicenter, randomized, double-blind, placebo-controlled, phase III trial evaluating primary efficacy and safety at twenty-four weeks. Arthritis Rheum. 2006;54(9):2793-2806. doi:10.1002/art.22025.
- Mease PJ, Cohen S, Gaylis NB, et al. Efficacy and safety of retreatment in patients with rheumatoid arthritis with previous inadequate response to tumor necrosis factor inhibitors: results from the SUNRISE trial. J Rheumatol. 2010;37(5):917-927. doi:10.3899/jrheum.090442.
- Food and Drug Administration (FDA). Rituxan. [Accessed October8, 2021]. Available from: https://www.accessdata.fda.gov/drugsatfda_docs/label/2021/103705s5464lbl.pdf.
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