Effect of BMI on Response to Abatacept in Psoriatic Arthritis

The effect of body mass index (BMI) on response to subcutaneous abatacept in patients with psoriatic arthritis (PsA) was assessed in a post hoc analysis of a phase 3 trial, and the results were published in RMD Open.¹

The Active Psoriatic Arthritis Randomized Trial (ASTRAEA) (ClinicalTrails.gov Identifier: NCT01860976)² included patients with active PsA and an inadequate or intolerant response to ≥1 non-biologic disease-modifying antirheumatic drugs (bDMARDs), who were randomly assigned 1:1 to receive either 125 mg abatacept or placebo every week for 24 weeks. Treatment with DMARDs, nonsteroidal anti-inflammatory drugs, and oral corticosteroids, if any, was continued.

Results were analyzed based on the primary end point, defined as the percentage of patients with ≥20% improvement response per the American College of Rheumatology (ACR20) criteria. Patients without improvements at week 16 were given abatacept for 28 weeks; patients with incomplete data were considered non-responders.

Results showed that patients with PsA had a BMI greater than that in the general population, and abatacept treatment increased ACR20 response vs placebo.

In order to assess the effect of BMI on response to abatacept, baseline BMI data (underweight/normal, <25 kg/m²; overweight, 25-30 kg/m²; obese, >30 kg/m²), along with patient demographics and disease characteristics, were analyzed in this study. Treatment response at week 24 was evaluated using data from the ACR20 response, Disease Activity Score in 28 joints (DAS28), C-reactive protein ≤3.6 or <2.6, and the Health Assessment Questionnaire-Disability Index response.

Available baseline BMI data showed that in patients in the abatacept group vs placebo, 14.6% vs 18.6% were underweight/normal, 36.3% vs 27.1% were overweight, and 49.1% vs 54.3% were obese, respectively.

In the multivariate analysis, among patients in the abatacept group in the obese or overweight subgroup vs the underweight/normal BMI subgroup, no significant differences were found in the likelihood of achieving week-24 treatment outcomes compared with patients in the placebo group, who were less likely to achieve DAS28 <2.6 (odds ratio, 0.26; 95% CI, 0.08-0.87; P =.03).

Study limitations included using short-term data only and the early escape design of the ASTRAEA study.

“In summary, the results reported here indicate that BMI does not appear to impact the response to abatacept administered at the approved dose of 125 mg [subcutaneous] weekly in patients with PsA across multiple outcome measures, similar to reported findings in RA,” the researchers concluded.  

Disclosure: Several study authors declared affiliations with the pharmaceutical industry. Please see the original reference for a full list of authors’ disclosures.

References

1. McInnes IB, Ferraccioli G, D’Agostino M-A, et al. Body mass index and treatment response to subcutaneous abatacept in patients with psoriatic arthritis: a post hoc analysis of a phase III trial. RMD Open. doi:10.1136/rmdopen-2019-000934

2. Mease PJ, Gottlieb AB, van der Heijde D, et al. Efficacy and safety of abatacept, a T-cell modulator, in a randomised, double-blind, placebo-controlled, phase III study in psoriatic arthritis. Ann Rheum Dis. 2017;76:1550-1558.