The PROPER Study: A 48-Week, Pan-European, Real-World Study of Biosimilar SB5 Following Transition from Reference Adalimumab in Patients with Immune-Mediated Inflammatory Disease.

Background: The non-interventional PROPER study generated real-world evidence on clinical outcomes following transition in routine practice from reference adalimumab to the EMA-approved SB5 biosimilar adalimumab in patients with immune-mediated inflammatory disease.

Methods: Adults with rheumatoid arthritis (RA), axial spondyloarthritis (axSpA), psoriatic arthritis (PsA), Crohn's disease (CD), or ulcerative colitis (UC) were enrolled at 63 sites across Europe. Eligible patients received ≥ 16 weeks of routine treatment with reference adalimumab before transitioning to SB5, and were followed for 48 weeks post-transition. The primary objective was to evaluate candidate predictors (clinically relevant baseline variables with incidence ≥ 15% by indication cohort) associated with persistence on SB5 at 48 weeks post-initiation. Key primary outcome measures were persistence on SB5 (estimated by Kaplan-Meier methodology) and clinical characteristics and disease activity scores at the time of transition to SB5 treatment (baseline).

Results: A total of 955 eligible patients were enrolled (RA, n = 207; axSpA, n = 127; PsA, n = 162; CD, n = 447; UC, n = 12), of whom 932 (97.6%) completed follow-up and 722 (75.6%) were still receiving SB5 at week 48. Kaplan-Meier estimates (95% confidence interval, CI) of persistence on SB5 at week 48 for RA, axSpA, PsA, and CD were 0.86 (0.80-0.90), 0.80 (0.71-0.86), 0.81 (0.74-0.86), and 0.72 (0.67-0.76), respectively. The single candidate predictor associated with probability of SB5 discontinuation before week 48 was female sex [RA, axSpA, and CD cohorts; HR (95% CI): 3.53 (1.07-11.67), 2.38 (1.11-5.14), and 2.21 (1.54-3.18), respectively]. Disease activity scores remained largely unchanged throughout the study, with proportions by cohort in remission at baseline versus week 48 being 59.2% versus 57.2%, 81.0% versus 78.0%, 94.7% versus 93.7%, and 84.0% versus 85.1% for patients with RA, axSpA, PsA, and CD, respectively. Similarly, the SB5 dosing regimen remained unchanged for the majority of patients from baseline to week 48, the most common regimen being 40 mg every 2 weeks. In total, 232 patients (24.3%) reported at least one adverse drug reaction, and most events were mild; eight patients (3.9%) in the RA cohort experienced nine serious adverse events (SAEs; two possibly related to SB5); eight patients (4.9%) in the PsA cohort experienced nine SAEs (one possibly related to SB5); 22 patients (4.9%) in the CD cohort experienced 27 SAEs (four possibly related to SB5); and no SAEs were observed in the UC cohort.

Conclusions: With the exception of female sex in RA, axSpA, and CD, none of the candidate predictors were associated with SB5 discontinuation. Persistence on SB5 was high, treatment effectiveness was maintained, and no safety signals were detected.

Trial registration: This trial is registered with ClinicalTrials.gov: NCT04089514.