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FRI0424 Role of baseline c-reactive protein in response to infliximab plus naproxen vs naproxen alone in patients with axial spondyloarthritis in the infast study
  1. J. Sieper1,
  2. M. Rudwaleit2,
  3. J. Lenaerts3,
  4. J. Wollenhaupt4,
  5. L. Myasoutova5,
  6. S. Park6,
  7. Y. Song7,
  8. R. Yao8,
  9. M. Govoni9,
  10. D. Chitkara10,
  11. N. Vastesaeger11
  1. 1Rheumatology
  2. 2Medicine, University Clinic Benjamin Franklin, Berlin, Germany
  3. 3Rheumatology, Practice Rheumatology, Hasselt, Belgium
  4. 4Rheumatology, Schön-Klinik, Hamburg, Germany
  5. 5Kazan State Medical University, Kazan, Russian Federation
  6. 6Catholic University of Korea
  7. 7Rheumatology, Seoul National University, Seoul, Korea, Republic Of
  8. 8Merck Sharp and Dohme, Kenilworth, United States
  9. 9Merck Sharp and Dohme, Rome, Italy
  10. 10Merck Sharp & Dohme, Kenilworth, United States
  11. 11Immunology, Merck Sharp and Dohme, Brussels, Belgium


Background Baseline inflammation has been shown to influence response to TNF alpha antagonist treatment in patients with axial spondyloarthritis (SpA).

Objectives To evaluate the role of C-reactive protein (CRP) in the response to treatment with infliximab (IFX)+nonsteroidal anti-inflammatory drugs (NSAIDs) vs NSAIDs alone in patients with axial SpA who have early, active disease.

Methods The INFAST trial was a double-blind, randomized controlled trial of IFX in biologic-naïve patients 18–48 years of age with early, active axial SpA (ASAS criteria, disease duration ≤3 years, chronic back pain, and active inflammation of the SI joints on MRI). Patients naïve to NSAIDs or treated with a submaximal dose of NSAIDs were randomized (2:1) to receive 28 weeks of treatment with either IV IFX 5 mg/kg (weeks 0, 2, 6, 12, 18, and 24)+naproxen (NPX) 1000 mg/d or IV placebo (PBO)+NPX 1000 mg/d. ASAS partial remission was evaluated in patients with high CRP (>upper limit of normal [ULN], per local laboratory limits) or low CRP (≤ULN). Response was also evaluated in patients who met the NY modified criteria for AS by SI X-ray (bilateral ≥grade 2 or unilateral ≥grade 3, based on local rheumatologist judgement) and were not naïve to NSAIDs (AS group) versus patients who did not meet radiographic criteria for AS (nr-axSpA group). Data were analyzed descriptively.

Results 156 patients were included in efficacy analyses. Overall, ASAS partial remission rate was greater for the IFX+NPX group (n=105) than the PBO+NPX group (n=51) (61.9% vs 35.3%, P=0.0021). For patients treated with IFX+NPX, partial remission rate was greater in the 49 patients with high CRP than in the 44 with low CRP (71.4% vs 59.1%). However, for patients treated with NPX alone, remission rates were similar whether CRP was high or low (40.7% [n=27] vs 38.5% [n=13]). In analysis of the AS and nr-axSpA groups, partial remission was greater in the AS group than the nr-axSpA group after treatment with IFX+NPX (72.2% [n=54] vs 56.4% [n=39]); after treatment with NPX alone, partial remission was greater in the nr-axSpA than the AS group (46.7% [n=25] vs 36.0% [n=15]). This pattern might be explained by the higher baseline mean CRP values in the AS group (n=83) than the nr-axSpA group (n=63) (CRP 2.59 vs 0.92 mg/dL). Within the AS group, the difference between the 2 treatments was clear in patients with high baseline CRP (IFX+NPX, 75.8% [n=33] vs NPX, 30% [n=20]); but not with low baseline CRP (IFX+NPX, 66.7% [n=21] vs NPX, 60% [n=5]). This pattern was not observed in the nr-axSpA group, perhaps because of low baseline CRP or because of the small number of subjects available for analysis.

Conclusions Elevated baseline CRP was associated with a better response to IFX therapy, even within a population of axial SpA patients with early disease and established MRI inflammation at baseline.

Disclosure of Interest J. Sieper Grant/research support from: Abbott, Merck, Pfizer, Janssen, Consultant for: Abbott, Merck, Pfizer, UCB, Roche, Lilly, Novartis, Speakers bureau: Merck, Abbott, Pfizer, UCB, M. Rudwaleit Consultant for: Abbott, BMS, MSD, Pfizer, UCB, Speakers bureau: Abbott, BMS, MSD, Pfizer, UCB, Roche, J. Lenaerts Consultant for: Abbott, BMS, MSD, Pfizer, Roche, Astra Zeneca., J. Wollenhaupt Consultant for: Abbott, Biotest, BMS, Chugai, MSD, Medac, Merck, MSD, Pfizer, Roche, and UCB., Speakers bureau: Abbott, Biotest, BMS, Chugai, MSD, Medac, Merck, MSD, Pfizer, Roche, and UCB., L. Myasoutova: None Declared, S. Park: None Declared, Y. Song: None Declared, R. Yao Employee of: Merck, M. Govoni Employee of: Merck, D. Chitkara Employee of: Merck, N. Vastesaeger Employee of: Merck

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