NO CORRELATION BETWEEN BODY MASS INDEX AND CLINICAL RESPONSE TO INFLIXIMAB: POST-HOC ANALYSIS OF PLANETRA

Abstract

Background Rheumatoid Arthritis (RA) patients with high body mass index (BMI) have been known to respond less well to anti-tumor necrosis factors (TNFs), especially infliximab. The post-hoc analysis of PLANETRA [1], a randomized controlled trial, was carried out to evaluate the influence of BMI on clinical response to infliximab (both infliximab originator and its biosimilar) in a large number of patients with RA.

Objectives To investigate the association between BMI and clinical response to infliximab in patients with RA.

Methods BMI was calculated before initiation of infliximab treatment in 606 patients with RA in PLANETRA. Patients were classified into 3 groups as normal weight (<25 kg/m2), overweight (≥25-<30 kg/m2) and obesity (≥30 kg/m2) according to the WHO BMI categories. Changes in disease activity were assessed at weeks 14, 30 and 54 with the Disease Activity Score in 28 joints (DAS28 [CRP]), Health Assessment Questionnaire (HAQ), and Short Form Health Survey (SF-36) based on BMI categories.

Results The proportion of patients with normal weight, overweight and obesity were 43.1%, 36.1% and 20.8%, respectively. Baseline characteristics were comparable among BMI subgroups in gender, height and weekly MTX dose given to patients. The mean DAS28 (CRP) at baseline was significantly higher in obesity group (5.80±0.87, 5.72±0.86 and 6.15±0.78 for normal weight, overweight and obesity, respectively; P<0.0001). But no significant differences were observed when comparing the mean change from baseline at Week 14 (-2.02 vs. -1.89 vs. -1.99), Week 30 (-2.25 vs. -2.10 vs. 2.17) and Week 54 (-2.27 vs. -2.20 vs. -2.22) among BMI subgroups. Similar results were observed when analysing biosimilar infliximab (CT-P13) and innovator infliximab (INX) separately up to Week 54 [Figure 1].

HAQ score was significantly higher in obese patients at baseline (1.55±0.55, 1.56±0.62 and 1.71±0.50, for normal weight, overweight and obesity, respectively; P=0.0278). However, there was no significant difference of mean change from baseline in HAQ at Week 14 (-0.56 vs. -0.48 vs. -0.55), Week 30 (-0.56 vs. -0.54 vs. -0.56) and Week 54 (-0.59 vs. -0.56 vs. -0.57) when assessed by BMI categories. In addition, improvements from baseline in both physical and mental component summary (PCS and MCS) scores were similar at weeks 14, 30 and 54 regardless of BMI (Table 1).

Conclusions The BMI does not affect the clinical response to infliximab in patients with RA. No significant association was found between BMI and clinical response by DAS28 (CRP), HAQ and SF-36. Therefore, the weight-based dosing of infliximab is appropriate in RA patients.