Safety and efficacy of non-medical switch from innovator to generic tofacitinib: a 3-month observational study in rheumatoid arthritis patients

Aim: Rheumatoid arthritis (RA) is a chronic autoimmune disease characterized by systemic inflammation. Following the expiry of the patent for innovator tofacitinib (Xeljanz), generic tofacitinib formulations such as Tozib have become available. This study evaluated the impact of a non-medical switch from innovator tofacitinib to generic tofacitinib on disease activity and flare rates over 3 months in patients with RA. Methods: This retrospective multicenter observational study in Malaysia included 36 patients with RA in remission or low disease activity who underwent a non-medical switch from innovator to generic tofacitinib. Disease activity was assessed at baseline and 3 months using the Disease Activity Score-28 erythrocyte sedimentation rate (DAS28-ESR). Flare was defined as an increase in DAS28-ESR of ≥ 1.2, or ≥ 0.6 if the concurrent DAS28-ESR was ≥ 3.2. Results: Thirty-six patients with RA who switched from reference medication to generic tofacitinib were included; 88.9% were female, with a mean age of 64.1 ± 9.4 years. Patients had longstanding disease, with a median disease duration of 15.5 years (IQR 8.8–19.0), and had received originator tofacitinib for a mean duration of 3.48 ± 1.71 years prior to switching. At 3 months post-switch, disease activity remained stable, with no significant change in median DAS28-ESR from 2.17 (IQR 1.19) to 2.45 (IQR 1.03) (p = 0.141). Although 16.7% of patients showed a DAS28-ESR increase of ≥ 0.6, none had DAS28-ESR ≥ 3.2 at 3 months. Only one patient demonstrated a DAS28-ESR change ≥ 1.2 after switching, with no new safety concerns observed. Conclusions: Our findings suggest that non-medical switching from reference medication to generic tofacitinib did not significantly affect short-term disease control or safety in RA patients over a 3-month follow-up period. These results provide preliminary real-world evidence supporting generic substitution; however, further studies with larger sample sizes and longer follow-up are warranted.