Response to: ‘Mandatory, cost-driven switching from originator etanercept to its biosimilar SB4: possible fallout on non-medical switching’ by Cantini and Benucci

Comparative Effectiveness and Persistence of SB4 and Reference Etanercept in Patients With Psoriatic Arthritis in Norway

OBJECTIVE

We aim to compare drug effectiveness and persistence between the reference etanercept (ETN) and ETN biosimilar SB4 in patients with psoriatic arthritis (PsA) naive to ETN and to investigate drug effectiveness and persistence in those undergoing a mandatory nonmedical switch from ETN to SB4.

METHODS

We used a retrospective comparative database study including 1,138 patients with PsA treated with ETN or SB4 (years 1999-2021) in Norway. Disease activity score in 28 joints (DAS28) and drug persistence were compared between unmatched ETN (n = 644) and SB4 (n = 252) cohorts and in matched analyses (n = 144, both cohorts) at baseline using a propensity score (PS) to adjust for confounders. Drug persistence was analyzed with the Kaplan-Meier method.

RESULTS

In unmatched analyses, difference in change from baseline between ETN (n = 140) and SB4 (n = 132) for DAS28 at one year was mean 0.67 (95% confidence interval [CI] 0.38-0.96) in favor of ETN. In PS-matched analyses, the difference in change from baseline between ETN (n = 54) and SB4 (n = 54) was mean 0.09 (95% CI -0.33 to 0.50), and the mean difference assessed with an analysis of covariance model was 0.01 (95% CI -0.38 to 0.40), both within predefined equivalence margin (±0.6). Drug persistence at one year was mean 0.75 (95% CI 0.71-0.78) for ETN, mean 0.58 (95% CI 0.51-0.63) for SB4, hazard ratio (HR) 2.45 (95% CI 2.02-2.97) in unmatched analysis, and mean 0.55 (95% CI 0.46-0.63) for ETN, mean 0.60 (95% CI 0.51-0.67) for SB4, HR 1.29 (95%CI 0.94-1.76) in PS-matched cohorts.

CONCLUSION

At one year, outcomes for PsA disease activity and drug persistence were comparable for patients treated with either ETN or SB4. In patients undergoing a mandatory nonmedical switch from ETN to SB4, drug effectiveness was maintained during a two-year period.

Forty-Eight-Month Monitoring of Disease Activity in Patients with Long-Standing Rheumatoid Arthritis Treated with TNF-α Inhibitors: Time for Clinical Outcome Prediction and Biosimilar vs Biologic Originator Performance

BACKGROUND AND OBJECTIVES

Long-term treatment of patients with rheumatoid arthritis with tumor necrosis factor-α inhibitors leads to initial changes in disease activity that can predict a late treatment response. This observational and retrospective study aimed to determine when it is possible to foresee the response to therapy in the case of long-standing rheumatoid arthritis comparing also the efficacy of the original biologics with their biosimilars.

METHODS

A total of 1598 patients were recruited and treated with the original biologics, adalimumab and etanercept, or with biosimilars. Patients were monitored over a period of 48 months and disease activity scores (28-Joint Disease Activity Score, Simplified Disease Activity Index, and Clinical Disease Activity Index) were measured every 6 months.

RESULTS

No differences in disease activity levels were observed in etanercept versus biosimilars (GP2015/SB4) and adalimumab versus biosimilar (GP2017) patient groups. All scores significantly decreased in all treatments during the first 18 months of therapy, and after 24 months reached a minimum that lasted up to 48 months.

CONCLUSIONS

We conclude that biosimilars of adalimumab and etanercept have equivalent effectiveness over a long period of time compared to their originator drugs, and also that the levels of disease activity after 6 months of tumor necrosis factor-α inhibitors (originator drugs and biosimilars) might predict the response to therapy at 4 years in patients with long-standing rheumatoid arthritis.

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

OBJECTIVES

In 2018, a nationwide mandatory switch from originator to biosimilar adalimumab was conducted in Denmark. The available biosimilar was GP2017 (Hyrimoz) in Eastern regions and SB5 (Imraldi) in Western regions. We aimed to assess the comparative effectiveness of GP2017 versus SB5 in patients with rheumatoid arthritis (RA)/psoriatic arthritis (PsA)/axial spondyloarthritis (AxSpA).

METHODS

Observational cohort study based on the DANBIO registry with geographical cluster pseudo-randomisation, analysed by emulating a randomised clinical trial. Main outcome was adjusted 1-year treatment retention (Cox regression). Furthermore, 6 months' remission rates (logistic regression), reasons for withdrawal and back-switching to originator were investigated (overall and stratified by indication).

RESULTS

Overall, of 1570 eligible patients, 1318 switched and were included (467 RA/321 PsA/530 AxSpA); 623 (47%) switched to GP2017, 695 (53%) to SB5. Baseline characteristics of the two clusters were largely similar, but some differences in registration practice were observed. The combined 1-year retention rate for the two biosimilars was 89.5%. Compared with SB5, estimated risk of withdrawal for GP2017 was lower (HR 0.60; 95% CI 0.42 to 0.86) and 6 months' remission rate was higher (OR 1.72; 95% CI 1.25 to 2.37). Stratified analyses gave similar results (statistically significant for RA). During 1 year, 8.5% and 12.9% withdrew GP2017 and SB5, respectively (primarily lack of effect and adverse events), of whom 48 patients (3.6%) back-switched.

CONCLUSION

This head-to-head comparison of GP2017 versus SB5 following a mandatory switch from the originator indicated differences in effectiveness in routine care. This may reflect a true difference, but other explanations, for example, differences in excipients, differences between clusters and residual confounding cannot be ruled out.