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P362 Faecal calprotectin is an early predictor of endoscopic response and histological remission after the start of vedolizumab

R. W. M. Pauwels*1, A. C. de Vries1, J. C. Goet1, N. S. Erler2, C. J. van der Woude1

1Erasmus MC, Department of Gastroenterology and Hepatology, Rotterdam, The Netherlands, 2Erasmus MC, Department of Biostatistics, Rotterdam, The Netherlands

Background

Early prediction of the effect of vedolizumab (VDZ) In IBD patients is of paramount importance to guide clinical decisions. We aimed to assess the potential of serial faecal calprotectin (FC) levels after start the of VDZ to predict endoscopic response and histological remission.

Methods

Patients who started VDZ with endoscopic inflammation and FC > 100 µg/g were included. FC was tested at Week 2, 4, 8, and 16. Endoscopy was scheduled at Week 16. Endoscopic response was defined as an SES-CD reduction ≥50%, Rutgeerts score reduction or Mayo score reduction of ≥1. At Week 16 endoscopy, ileum and segmental colon biopsies were collected. Histological severity was scored accordingly on a 4-point scale. Median FC levels at the FU time points and the relative change in FC between baseline and Week 16 were assessed with the Wilcoxon rank-sum test. ROC statistics were used to determine an FC cut-off point with the best discriminatory performance and to assess the predictive value of FC levels at the FU time points.

Results

A total of 40 patients (24 CD, 14 UC and 2 IBD-U) (42% males, median age 40 (28–51) years (IQR)) were included. 33/40 patients (83%) were anti-TNF exposed, of whom 28/33 (85%) were refractory. In 26/40 patients (65%) VDZ was combined with steroid induction therapy and completely tapered at Week 16 in 18/26 (69%) patients. Week 16 endoscopic response rates were 11/16 (69%) in UC and 12/24 (50%) in CD (p = 0.33). Median FC levels (µg/g) are depicted in Figure 1, and were significantly lower when compared with FC in patients without endoscopic response. Patients with endoscopic response had a significant decrease in FC level at Week 2 when compared with patients without endoscopic response (p = 0.015). FC < 250 µg/g at Week 2 predicted endoscopic response (AUC = 0.77) with a sensitivity of 70%, specificity 93%, PPV 94%, and NPV 67%. At Week 8 (AUC = 0.84) this was a sensitivity of 62%, specificity 100%, PPV 100%, and NPV 55%. FC predicted histological remission at Week 8 (AUC = 0.88): sensitivity 89%, specificity 89%, PPV 80%, and NPV 94%.

Conclusion

Although delayed clinical effectiveness of VDZ has been reported previously, VDZ induces as early as Week 2 a significant decrease of FC levels in IBD patients with an endoscopic response at Week 16. At 8 weeks after the initiation of VDZ, FC <250 µg/g accurately predicts endoscopic response and histological remission in this cohort.

Figure 1. Serial FC measurements in IBD patients after the start of vedolizumab.

Median faecal calprotectin levels (µg/g) in endoscopic responders: 921 at baseline, 201 at Week 2, 276 at Week 4, 139 at Week 8 and 134 at Week 16. In endoscopic non-responders: 1332, 1218 (p = 0.003), 946 (p = 0.005), 1286 (p < 0.001) and 974 (p < 0.001).