Background It has previously been shown that the majority of patients (pts) with active rheumatoid arthritis (RA) have a rapid response to certolizumab pegol (CZP) and that lack of improvement in DAS28 by Week (Wk) 12 predicts failure to achieve low disease activity (LDA) at later timepoints.¹

Objectives To investigate whether timing and magnitude of DAS28(ESR) response and swollen joint count (SJC) response to CZP during the first 12Wks of therapy can predict the likelihood of achieving LDA at Wk28 in a broad RA population, including pts with prior anti-TNF exposure, from the REALISTIC study.

Methods Following the 12Wk double blind phase (CZP 400mg/PBO at Wks 0, 2, 4, then CZP 200mg/PBO at Wks 6, 8, 10 plus current treatment), pts received open-label CZP 200mg every other week for ≥16Wks. The proportion of pts who achieved LDA (DAS28≤3.2) at Wk28 was assessed according to the level of DAS28 nonresponse (ie, DAS28 change from baseline [CFB] <0.3, 0.6, 0.9, 1.2, 1.5 and 1.8 units) and SJC nonresponse (quartiles for %CFB at Wk12: <29%, <60% and <85%) up to Wks 2, 6, or 12. Last observation carried forward (LOCF) imputation was used for pts who withdrew.

Results CZP-treated pts (N=851) had a mean baseline DAS28 of 6.4 and SJC of 11.8. Overall, 81.1% of pts had a ≥1.2 DAS28 response and 89.3% had a ≥29% change from BL in SJC by Wk12. LDA was achieved by 27.4% of the original CZP ITT population at Wk28. Failure to achieve LDA at Wk28 was dependent on the magnitude and timing of DAS28 and SJC change up to Wk12. Pts with DAS28 changes <0.3 by Wk 6 and <1.5 by Wk 12, had a <10% chance of having LDA at Wk28 (Table). Pts who failed to have a DAS change of 1.2 by Wk12 had a <4% chance of achieving LDA at Wk28 (Table). Pts who failed to have an SJC change of 29% by Wk12 had a 5% chance of achieving LDA at Wk28 (Table). For any given threshold in DAS or SJC, the failure to respond by a later timepoint was associated with a lower chance of achieving LDA at Wk28. At baseline, 37.6% of CZP pts had received prior TNF-inhibitor therapy. The proportion of pts achieving a DAS28 change ≥1.2 by Wk12 was similar between pts who had received prior TNF and those who had not (79.6% vs. 82.1%, respectively). Failure to achieve a DAS28 change of ≥1.2 by Wk12 was associated with <5% chance of achieving LDA at Wk28 for both groups.

Conclusions The majority of pts responded to treatment with CZP by Wk12 in this broad pt population. Likelihood of LDA at 28 weeks could be predicted early in the course of treatment with CZP based on the timing and magnitude of initial change in DAS28 or SJC in pts both naïve and exposed to prior anti-TNF.

1. van der Heijde D. et al. Ann Rheum Dis 2010;69(suppl 3):505

Disclosure of Interest M. Weinblatt Grant/Research support from: UCB Pharma, Consultant for: UCB Pharma, R. Fleischmann Grant/Research support from: UCB Pharma, Consultant for: UCB Pharma, O. Davies Employee of: UCB Pharma, K. Luijtens Employee of: UCB Pharma, D. van der Heijde Grant/Research support from: UCB Pharma, Consultant for: UCB Pharma, Speakers Bureau: UCB Pharma