1112: Biosimilar-to-Biosimilar Switching in Routine Care – Results on >1,600 Patients with Inflammatory Arthritis in the DANBIO Registry

Hafsah Nabi¹, Oliver Hendricks², Dorte Vendelbo Jensen³, Anne Gitte Loft⁴, Jens Pedersen⁵, Søren Just⁶, Kamilla Danebod⁷, Heidi Munk⁸, Salome Kristensen⁹, Natalia Manilo¹⁰, Ada Colic¹¹, Asta Linauskas¹², Pia Høger Thygesen¹³, Louise Christensen³, Maren Høgberget Kalisz³, Niels Lomborg¹⁴, Stavros Chrysidis¹⁵, Johnny Raun¹⁵, Marlene Andersen¹⁶, Frank Mehnert¹⁷, Niels Steen Krogh¹⁸, Merete L Hetland¹⁹ and Bente Glintborg²⁰, ¹DANBIO and Copenhagen Center for Arthritis Research (COPECARE), Center for Rheumatology and Spine Diseases, Centre of Head and Orthopedics, Rigshospitalet, Copenhagen, Denmark, ²Danish Hospital For Rheumatic Diseases, Sønderborg, Denmark, ³Department of Rheumatology, Gentofte and Herlev Hospital, Copenhagen University Hospital, Gentofte, Denmark, ⁴Aarhus University, Horsens, Denmark, ⁵Svendborg Hospital, Odense University Hospital, Odense, Denmark, ⁶Medicinsk Afdeling Svendborg Sygehus OUH, Odense, Denmark, ⁷Department of Rheumatology, Center for Rheumatology and Spine Diseases, Centre of Head and Orthopedics, Copenhagen University Hospital Rigshospitalet, Glostrup, Denmark, ⁸Department of Rheumatology, Odense University Hospital, Odense, Denmark, Odense, Denmark, ⁹Center of Rheumatic Research Aalborg, Department of Rheumatology, Aalborg University Hospital, Aalborg, Denmark, ¹⁰Department of Rheumatology, Frederiksberg Hospital, Copenhagen, Denmark, ¹¹Department of Rheumatology, Zealand University Hospital, Køge, Denmark, ¹²North Denmark Regional Hospital, Hjørring, Denmark, ¹³Department of Rheumatology, Slagelse Hospital, Slagelse, Denmark, ¹⁴Department of Rheumatology, Vejle Hospital Lillebælt, Vejle, Denmark, Odense, Denmark, ¹⁵Department of Rheumatology, Esbjerg Hospital, Esbjerg, Denmark, ¹⁶Department of Rheumatology, North Denmark Regional Hospital, Hjørring, Denmark, ¹⁷Aarhus University Hospital, Aarhus, Denmark, ¹⁸ZiteLab ApS, Frederiksberg, Denmark, ¹⁹Rigshospitalet, Glostrup, Denmark, ²⁰Rigshospitalet, Glostrup, Virum, Denmark

Background/Purpose: In routine care, biosimilar-to-biosimilar infliximab switching may occur to save costs (=non-medical switching). Previous studies have investigated the efficacy and safety of switches from originator infliximab to a corresponding biosimilar in patients with inflammatory rheumatic diseases (1). However, the outcomes after switching from one infliximab biosimilar to a second infliximab biosimilar remain scarcely investigated. Denmark has recently conducted a nationwide mandatory infliximab biosimilar-to-biosimilar switch. In this study, we aimed to investigate the effectiveness of switching infliximab biosimilars CT-P13-to-GP1111 among patients with rheumatoid arthritis (RA), psoriatic arthritis (PsA) and axial spondyloarthritis (AxSpA), including patients who had previously switched from originator (originator-experienced) to CT-P13 as well as patients who were originator-naïve.

Methods: Observational cohort study based on DANBIO registry linked with national patient registries (to identify prior comorbidities). Patients with RA, PsA or AxSpA who performed a biosimilar-to-biosimilar switch from CT-P13 to GP1111 between April 1^st 2019 and February 1^st 2020 were included. Patient were divided into two groups: originator-naïve and originator-experienced. Main outcomes in the two groups were one-year GP1111 treatment retention (Kaplan Meier "drug survival curves") and changes in disease activity 4 months before versus 4 months after switch in individual patients. Also, we identified clinical factors at baseline (=at time of switch) associated with withdrawal (multivariable Cox-regression analyses with Hazard Ratios (HR) including originator treatment history).

Results: Of 1,605 patients (685 RA/314 PsA/606 AxSpA, median disease duration 9 years, 37% in CDAI/ASDAS remission), 1,171 were originator-naïve (Table 1).

One-year retention rates of GP111 were 83% (95% confidence interval (CI): 81-85%) and 92% (90-95%) for the originator-naïve and originator-experienced, respectively (Figure 1). Changes in disease activity 4 months pre- and post-switch were close to zero for all disease activity measures (e.g. DAS28, ASDAS, VAS pain, not shown).

Factors associated with higher GP1111 retention rates were being originator-experienced compared to originator-naïve in RA (HR=0.4 (95%CI:0.2-0.7)) and PsA (HR=0.2 (0.1-0.8)), but not in AxSpA: HR=0.6 (0.3-1.2), and lower disease activity at baseline (Table 2).

Conclusion: In this real-world observational study of >1,500 patients with inflammatory arthritis, one-year retention following a mandatory nationwide infliximab biosimilar-to-biosimilar switch was high. Retention was higher in originator-experienced and in patients with low disease activity, suggesting outcomes to be affected by patient- rather than drug-related factors.
Table 1. Characteristics at time of biosimilar-to-biosimilar infliximab switch (according to previous originator treatment history and stratified by indication)

Figure 1. Kaplan-Meier plots of crude treatment retention rates in GP1111 treated patients (A. Originator-naïve and B. Originator-experienced switchers)*

Table 2. Baseline variables associated with GP1111 treatment withdrawal, performed in all switch patients (n= 1,605)
Disclosures: H. Nabi, Sandoz (Hexal); O. Hendricks, Pfizer, AbbVie/Abbott, Eli Lilly; D. Jensen, None; A. Loft, AbbVie, Eli Lilly Denmark A/S, Jannsen-Cilag A/S, Novartis, Pfizer, UCB; J. Pedersen, None; S. Just, None; K. Danebod, None; H. Munk, None; S. Kristensen, None; N. Manilo, None; A. Colic, None; A. Linauskas, None; P. Thygesen, None; L. Christensen, None; M. Kalisz, None; N. Lomborg, None; S. Chrysidis, None; J. Raun, None; M. Andersen, None; F. Mehnert, None; N. Krogh, None; M. Hetland, Sandoz, Novartis, Pfizer, Eli Lilly, Medac; B. Glintborg, BMS, Pfizer, AbbVie/Abbott.