Effectiveness of non-medical switch from adalimumab bio-originator to SB5 biosimilar and from ABP501 adalimumab biosimilar to SB5 biosimilar in patients with chronic inflammatory arthropathies: a monocentric observational study.

Objectives: The use of biosimilars is constantly growing, prompting healthcare payers to encourage the switch to these drugs which are less expensive than the reference bio-originator. While switching from a bio-originator to a biosimilar is supported by increasing evidence, data on the switch between different biosimilars of the same reference product are scant. Our study aimed to evaluate the effectiveness of the non-medical switch both between adalimumab (ADA) bio-originator and SB5 biosimilar and between two different ADA biosimilars in patients with inflammatory chronic arthritis.

Methods: We observed adult patients with a diagnosis of rheumatoid arthritis (RA), psoriatic arthritis (PsA), and axial spondyloarthritis (axSpA) treated with ADA bio-originator or ABP501 ADA biosimilar (Amgevita) who switched to SB5 ADA biosimilar (Imraldi) for administrative/economic reasons. Patients were followed up for 4 months.

Results: One hundred and ten patients [33 RA, 40 PsA, 37 axSpA; F:M= 49:61; median age 56 years (25th-75th percentile 48-66)] switched from ADA bio-originator to SB5. After 4 months (T4), we observed a significant reduction of patients in remission/low disease activity (baseline 92.7% vs. T4 80.9%; p=0.009), with a risk of moderate-high disease activity significantly higher after the switch [RR 2.6 (95% IC 1.2 to 5.7), p=0.01]. However, no differences were found in DAS28-CRP, DAPSA, ASDAS-CRP, and BASDAI, while patients with RA and PsA experienced a worsening in the patient global assessment-VAS (p=0.04 and p=0.02, respectively), and in patients with PsA a worsening in HAQ was also observed (p=0.03). Forty patients switched from ABP501 biosimilar to SB5 [12 with RA, 25 with PsA, and 3 with axSpA; F:M=24:16; median age 56 years (25th-75th percentile 44-66)]. After 4 months, no differences in DAS28-CRP and DAPSA nor in the percentage of patients in remission/low disease activity were found compared to baseline. Likewise, no differences were found in patient-reported outcomes (PROs).

Conclusions: Our results provide a reassuring profile of effectiveness when switching from ADA originator to one of its biosimilars and between two different biosimilars. However, the worse outcome in PROs in patients initially treated with the bio-originator addresses the attention to a possible nocebo response, which should encourage comprehensive communication with patients.