Biosimilars Confer Different Rates of Withdrawal, Remission in Patients With Rheumatoid Diseases

GP2017, an adalimumab biosimilar, was associated with a lower risk for withdrawal and higher 6-month remission rates compared with adalimumab biosimilar SB5 in patients with inflammatory rheumatic diseases, according to study results published in the Annals of the Rheumatic Diseases.

Danish National guidelines ordered a mandatory switch to biosimilar adalimumab for economic reasons in 2018. Available biosimilars included SB5, available in Denmark’s Western regions, and GP2017, available in the nation’s Eastern regions. As no head-to-head trials comparing the 2 adalimumab biosimilars had been conducted, researchers evaluated the comparative efficacy of the 2 biosimilars in 1318 Danish patients (median age, 56 years; women, 49%) with rheumatoid arthritis (RA), psoriatic arthritis (PsA), and spondyloarthritis (axSpA) who switched from the originator by November 2018.

The observational cohort study relied on data from the Danish DANBIO quality registry. The registry was established in 2000 and includes follow-up data of more than 95% of adult patients with rheumatoid diseases who have been treated with biological disease-modifying antirheumatic drugs.

Roughly half of all patients in the study switched from the originator to either GP2017 (47%) or SB5 (53%). Among the DANBIO patients with RA, 214 switched to GP2017 and 253 switched to SB5. In the group of patients with PsA, 148 patients switched to GP2017 and 173 patients switched to SB5. A total of 261 and 269 patients with axSpA switched to GP2017 and SB5, respectively.

The primary outcome of the head-to-head comparative study was the adjusted 1-year treatment retention rate, evaluated by Cox regression. The investigators also evaluated remission rates at 6 months and reasons for withdrawal. These data were retrieved from DANBIO.

Approximately 61% of patients were in remission at baseline. At 1 year, the crude treatment retention rate was 89.5%. The estimated risk for withdrawal at 1 year for GP2017 was significantly lower compared with SB5 (hazard ratio [HR], 0.60; 95% CI, 0.42-0.86; P =.005). In addition, the 6-month remission rate was significantly higher for GP2017 vs SB5 (odds ratio [OR], 1.72; 95% CI, 1.25-2.37; P =.001).

In analyses stratified by indication, the age- and sex-adjusted HR favored GP2017 over SB5 in patients with RA (HR, 0.50; 95% CI 0.28-0.90; P =.021). No significant differences between biosimilars were found in regard to treatment withdrawal for patients with PsA (HR, 0.97; 95% CI, 0.46-2.02; P =.927) or axSpA (HR, 0.75; 95% CI, 0.42-1.33; P =.317).

After 1 year, a total of 8.5% had withdrawn from GP2017 and 12.9% of patients had withdrawn from SB5. Treatment withdrawal was primarily due to adverse events and lack of effect. More patients who had switched to SB5 withdrew from treatment due to remission and loss to follow-up, among other reasons.

A limitation of this study was the analysis of data for only Danish residents. As such, the findings may not be applicable across patients with rheumatoid diseases from healthcare settings in other regions.

Although the researchers suggest the findings may show “a true difference between the active drugs,” other explanations such as “differences in excipients, differences between clusters and residual confounding cannot be ruled out,” the study authors concluded.   

Disclosure: Multiple authors declared affiliations with the pharmaceutical industry. Please refer to the original article for a full list of disclosures.

Reference

Nabi H, Georgiadis S, Loft AG, et al. Comparative effectiveness of two adalimumab biosimilars in 1318 real-world patients with inflammatory rheumatic disease mandated to switch from originator adalimumab: nationwide observational study emulating a randomised clinical trial. Ann Rheum Dis. Published online April 29, 2021. doi:10.1136/annrheumdis-2021-219951