Disease Activity Unaffected in Patients with Psoriatic Arthritis Who Switched from Infliximab to a Biosimilar

Analysis of a Danish registry found that a switch from infliximab (Remicade) to a biosimilar called Remsima did not appear to change disease activity status or increase the risk of flares in patients with psoriatic arthritis or rheumatoid arthritis.

However, adverse events and lack of effect led a significant percentage of the cohort to stop taking the biosimilar within 3 months of the initial transition — even though most such patients had been taking the original version of infliximab for years.

Danish authorities decided last year to save money by using the biosimilar in place of the original infliximab for everyone using the nation’s public health care program. Investigators assessed outcomes for 647 patients during the last 3 months before the switch and the first 3 months after the switch.

The cohort included 300 patients with rheumatoid arthritis, 219 with axial spondylitis, 96 with psoriatic arthritis and 32 with some other condition. Cohort members, whose median age was 56 years (interquartile range 45-66 years), had been using infliximab for an average of 6.7 years (interquartile range 4.1-9.4 years) before switching to the biosimilar. Most of them had never used any other biologic disease-modifying drug, but 69% of all patients with psoriatic arthritis and rheumatoid arthritis were also taking methotrexate during the study period.

For patients with rheumatoid arthritis and psoriatic arthritis, the mean disease activity score in 28 joints was 2.3 at all 3 measuring points: 3 months before the switch, at the switch and 3 months after the switch. Health Assessment Questionnaire scores averages started at 0.6 3 months before the switch, were unchanged at the switch point and had fallen to 0.5 3 months after the switch. C-reactive protein levels began at 4.0 mg/L, remained the same at the switch and were 6.0 mg/L 3 months later. Global visual analog scale score averages were 26mm 3 months before the switch, 27 mm at the switch and 26 mm after another 3 months.

“Disease activity was largely unaffected in the majority of patients 3 months after non-medical switch to biosimilar Remsima and comparable to the fluctuations observed in the 3 months prior to the switch,” the investigators wrote in an abstract they presented at the Scientific Sessions of the European League Against Rheumatism’s annual congress. “However, several patients (∼6%) stopped treatment due to [lack of effect] or [adverse events]. This warrants further investigation before such a non-medical switch can be recommended.”

Overall, 45 patients stopped treatment during the follow-up period. The reason reported by 29 of those patients was insufficient effectiveness. The remaining 16 reported problems with various adverse effects: allergies to the medication (3), infections (2), rash (2) and unspecified problems (9).

Remsima was approved in Europe last year, and embraced by a number of national insurers in an effort to save costs. In the UK, for example, guidelines from the National Institute for Health and Care Excellence (NICE) state that the treatments should be regarded as identical and patients should be started on whichever is cheaper at any given time. (Remsima was about 10% cheaper when it hit the European market — 377 UK pounds per 100ml vial vs. 419 UK pounds per 100 ml of Remicade — but prices change regularly as makers vie for market share.)

In April, the US Food and Drug Administration approved a biosimilar made by the same company, Celltrion Inc., which will be called Inflectra in the US.