Effect of Filgotinib on Body Mass Index (BMI) and Effect of Baseline BMI on the Efficacy and Safety of Filgotinib in Rheumatoid Arthritis

IntroductionThis post hoc analysis of the phase 3 rheumatoid arthritis (RA) filgotinib clinical trial program assessed the effect of filgotinib on body mass index (BMI) in patients with RA and the impact of BMI on the efficacy and safety of filgotinib.MethodsFINCH 1-3 were randomized, double-blind, active- or placebo-controlled phase 3 trials of filgotinib 100 and 200 mg in patients with RA (N = 3452). BMI assessments included the mean change from baseline in BMI and the proportion of patients whose BMI increased by incremental thresholds. Efficacy measures included American College of Rheumatology (ACR) 20/50/70 response and low disease activity/remission according to Disease Activity Score 28 using C-reactive protein. The exposure-adjusted incident rate (EAIR) of adverse events (AEs) was assessed by baseline BMI, using integrated data from the FINCH 1-4 and the phase 2 DARWIN 1-3 studies (total filgotinib exposure = 8085 patient-years).ResultsMean change from baseline in BMI over time was similar across treatment arms. In most patients, BMI increased by & LE; 1 or 2 kg/m2 at both weeks 12 and 24, regardless of treatment group or baseline BMI; few patients had increases of & GE; 4 kg/m2. For most efficacy measures, filgotinib 200 mg was more efficacious than filgotinib 100 mg or active comparators or placebo across BMI subgroups. For the higher filgotinib dose, the EAIR of serious treatment-emergent AEs, venous thrombotic and embolic events, and major adverse cardiovascular events increased with increasing BMI.ConclusionsFilgotinib did not lead to substantial changes in BMI, and BMI did not appear to affect the efficacy of filgotinib.Trial RegistrationClinicalTrials.gov identifiers: NCT02889796, NCT02873936, NCT02886728, NCT03025308, NCT01888874, NCT01894516, NCT02065700. Some rheumatoid arthritis treatments cause patients to gain weight or are less effective in patients with obesity than in patients without obesity. Also, obesity can make rheumatoid arthritis worse. Filgotinib is a rheumatoid arthritis treatment that was evaluated in seven randomized clinical studies (FINCH 1-4 and DARWIN 1-3). We investigated whether filgotinib causes changes in weight and whether body mass index (BMI) affects the efficacy or safety of filgotinib. We analyzed how the BMI of patients who participated in FINCH 1, 2, or 3 changed over time. Most patients had a small increase in BMI (around 1-2 kg/m2) after 24 weeks of filgotinib treatment. This change in BMI was not affected by patients' BMI at baseline. Baseline BMI did not impact the efficacy of filgotinib, which was assessed using standard measures of disease activity. Filgotinib was more effective than other rheumatoid arthritis treatments and placebo in all patients, regardless of BMI subgroup. Using safety data from all seven clinical studies (FINCH 1-4 and DARWIN 1-3), we found that some adverse events occurred more often in patients with obesity (a BMI of & GE; 30 kg/m2) than in those without obesity. The increased adverse events included venous thrombotic and embolic events and major adverse cardiovascular events, for which obesity is a known risk factor. These results show that filgotinib did not substantially change BMI (which increased by around 1-2 kg/m2 in most patients), and that baseline BMI did not affect the efficacy of filgotinib.