Impact of Nonmedical Switches From Reference Infliximab to Biosimilars on Disease Control Within a Rheumatology Practice

Infliximab is an anti-tumor necrosis factor agent used to treat rheumatologic disease. Evidence on the safety of switching to biosimilars and the associated risk factors for flares/loss of disease control within rheumatology is limited. The primary objective is to evaluate nonmedical switches from reference infliximab to biosimilars in rheumatology on risks and level of disease control. This retrospective analysis of data was conducted on all adult patients at our institution's rheumatology clinics with a rheumatologic diagnosis who were stable on reference infliximab and switched to the formulary biosimilars infliximab-dyyb or infliximab-abda, during the study period. Patient demographics as well as concomitant rheumatologic medications, markers of disease control, and hospitalization data were collected. Of the 317 patients screened, 48 patients met inclusion criteria. A total of 29 patients (60.4%) were on reference infliximab and 19 patients (39.6%) were switched to biosimilar. Eight patients (42.1%) flared after a switch to biosimilar. Of the biosimilar patients, all patients were on infliximab-dyyb and were mandated to switch by insurance. Two patients who flared after switch to biosimilar (25%) had a delay in treatment due to attempts to receive prior authorization for reference infliximab. In the patients who switched to biosimilar, almost half experienced a flare. Two of these eight patients (25%) had a delay in treatment after the switch, which may be a risk factor for flaring/loss of disease control. Pharmacists should be following patients who switch to biosimilar closely during the transition period, to monitor for signs of flares/loss of disease control.