Adalimumab Originator vs. Biosimilar in Hidradenitis Suppurativa: A Multicentric Retrospective Study

This study aimed to compare adalimumab originator vs. biosimilar in HS patients, and to evaluate the effect of a switch to a biosimilar, or a switch back to the originator, in terms of treatment ineffectiveness. Patients with a diagnosis of HS were enrolled from 14 Italian sites. Treatment ineffectiveness was measured using Hurley score. The major analyses were 1) comparison between the two treatment groups (non-switcher analysis), and 2) the cross-over trend of Hurley score between treatment switchers (switcher analysis). Cox and Poisson regression models were used to compare the treatment ineffectiveness between groups. A total of 326 patients were divided into four groups: 171 (52.5%) taking originator; 61 (18.7%) patients taking biosimilar; 66 (20.2%) switchers; 28 (8.6%) switchers from originator to biosimilar and switched. A greater loss of efficacy was observed in the group allocated to the biosimilar than the originator group. The switcher analysis showed an effectiveness loss in the biosimilar compared to the originator. These results seem to indicate that a switch from one drug to the other may lead to a greater risk of inefficacy. A return to the previous treatment also does not ensure efficaciousness.