Background/Purpose: Etanercept (ETN) plus methotrexate (MTX) was shown to be superior to MTX plus another conventional disease-modifying anti-rheumatic drug (DMARD) in an open-label, randomized study of Latin American patients with rheumatoid arthritis (RA). Determining possible predictors of response would allow a more personalized approach to the treatment of RA in this heterogeneous population. The aim of this post hoc analysis was to identify potential predictors of response to 24- and 128-week treatment ETN+MTX in Latin American patients with RA.

Methods: During Phase 1 (24 weeks) of this study (NCT00848354), patients from Latin America with MTX-resistant, moderate to severe RA were randomized 2:1 to receive open-label ETN 50 mg/week plus MTX (ETN+MTX, n=281) or an additional conventional DMARD (hydroxychloroquine or sulfasalazine) plus MTX (DMARD+MTX; n=142). Phase 2 (104 weeks) was an optional extension period allowing the continuation with Phase 1 treatment or the addition, discontinuation or titration of the other DMARD therapy. In this analysis, response was defined as Disease Activity Score-28 for Rheumatoid Arthritis with erythrocyte sedimentation rate (DAS28-ESR) score < 2.6 (DAS28-ESR remission). Baseline variables between responders and non-responders were compared using chi-square test (discrete) or one-way ANOVA (continuous). Odds of attaining response in the ETN+MTX group at Weeks 24 and 128 (observed cases) were estimated using a stepwise logistic regression model.

Results: At 24 and 128 weeks, 26% (70/269) and 35% (n=19/54) of patients in the ETN+MTX group achieved DAS28-ESR remission, respectively. On average, Week 24 and Week 128 responders had lower baseline scores of ESR and PGA, and were more likely to be men than non-responders (Table 1). In addition, Week 24 responders were on average younger and had lower baseline total HAQ and VAS pain scores, compared to non-responders. Significantly higher odds of attaining remission at Week 24 were associated with baseline age ≤49 years, BMI >28.5 kg/m², disease duration >4.1 years, ESR ≤42 mm/h, PGA ≤6, and Total HAQ score ≤1.63; ESR ≤35 mm/h was a predictor of response at Week 128 (Table 2). Fewer predictors of response at Week 128 compared to Week 24 may be due to lower predictability of long-term events or due to a loss of statistical power, based on the smaller sample size for Week 128.

Conclusion: Factors that predicted response to therapy were younger age, higher body mass index, longer disease duration, and an overall lower disease activity. Limitations of this post hoc analysis include the small sample size for Week 128. Further studies are needed to confirm these predictors of response.

LARA Predictors of response_ACR2019_FOR SUBMISSION_Table 1

LARA Predictors of response_ACR2019_FOR SUBMISSION_Table 2

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/predictors-of-response-to-etanercept-methotrexate-treatment-post-hoc-analysis-of-a-randomized-open-label-study-in-latin-american-patients-with-rheumatoid-arthritis/