Biosimilar rituximab in biological naïve rheumatoid arthritis patients

Researchers from the Department of Rheumatology at the National Hospital in Calicut, Kerala, India prospectively studied 21 biological naïve patients (mean age 56 ± 4.2 years; 65% females, disease duration range 1.5‒7 years) with seropositive rheumatoid arthritis. These patients had active disease (disease activity score, DAS28 ESR > 5.1) for more than 3 months despite standard combination, conventional disease-modifying anti-rheumatic drug (DMARD) therapy (including oral or subcutaneous methotrexate at 15‒25 mg/week and low dose, i.e. < 7.5 mg/day prednisolone equivalent, glucocorticoids). All patients were treated with biosimilar rituximab (2 doses of 1,000 mg, 2 weeks apart) [1].

In the minimum 3-year follow-up in each of these patients several interesting observations were made:
1. At 3 months, significant improvement compared to baseline was noted in both DAS28 ESR (6.08 ± 0.36 vs 2.54 ± 0.8, p <0.0001) and health assessment questionnaire (HAQ; 1.98 ± 0.54 vs 1.14 ± 0.31, p < 0.0001) in these patients.
2. 19 patients were responders and in only two patients was there no improvement.
3. After 1 year, 12 patients were in remission and 7 patients had low disease activity (LDA; DAS28 ESR ≤ 3.2 to > 2.6).
4. Among those who maintained remission beyond 1 year, de-escalation of existing therapy (mainly gradual reduction and eventual cessation of hydroxylchloroquine in 7/12 and of glucocorticoids in 9/12 patients) was possible.
5. Three patients required re-treatment with biosimilar rituximab, one after 1.5 years and two after 2 years.
6. At the end of 3 years, sustained remission was noted in 10 patients and LDA in 9 patients.
7. No worsening of pre-existing interstitial lung disease was noted in the four affected individuals.
8. Infusion-related reactions were noted in two patients during the first infusion. No serious adverse events (SAEs) were observed in the prolonged follow-up period.

In conclusion in this small cohort of biological naïve patients with active rheumatoid arthritis, use of biosimilar rituximab resulted in prolonged benefit in the majority of patients and was well tolerated.

Conflict of interest
The authors of the research paper [1] declared that Vinod Ravindran had received consultation honorarium and grants to attend meetings from Dr Reddy’s Laboratories (manufacturer of biosimilar rituximab – Reditux), Pfizer/Wyeth, Intas, Zydus, Sanofi and Cipla. K K Roshique has no disclosures.

Abstracted by Dr Vinod Ravindran, Consultant Rheumatologist, Centre for Rheumatology, Calicut, Kerala, India.

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Reference
1. Roshique KK, Ravindran V. Efficacy and safety of a biosimilar rituximab in biologic naïve patients with active rheumatoid arthritis. Clin Rheumatol. 2015;34(7):1289-92.

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