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P546 Therapeutic drug monitoring of vedolizumab in inflammatory bowel disease

N. Torres1, D. Martín Arranz2, M. Sánchez Azofra2, E. Martín Arranz2, L. Garcia2, P. Nozal3, J. Pascual1, I. Apraiz1, M. López1, D. Arteta1, D. Nagore*1

1Progenika Biopharma, S.A, A Grifols company, Derio, Spain, 2Unidad de Enfermedad Inflamatoria Intestinal Hospital Universitario La Paz, Madrid, Spain, 3Unidad de Inmunología, Madrid, Spain

Background

Clinical utility of infliximab and adalimumab therapeutic drug monitoring (TDM) is unquestionable. However, little is known on the clinical utility of TDM-guided patient management for vedolizumab (VDZ) in inflammatory bowel disease (IBD), and more studies are needed to understand the correlation between VDZ trough levels (VTL) and clinical response, and to establish solid cut-off therapeutic levels of VDZ.

Methods

A prospective cross-sectional observational study is ongoing at La Paz University Hospital (Madrid, Spain) to explore the correlation between VTL and loss of clinical response in IBD patients treated with VDZ. Trough serum samples were collected from 21 IBD patients at baseline and during the course of treatment from 4 months to 2 years. VTL and anti-VDZ antibodies were measured with Promonitor®-VDZ and Promonitor® Anti-VDZ tests (Progenika, a Grifols company, Spain), based on ELISA technology, respectively. All statistical analysis performed used a non-parametric approach (JMP software 14.0).

Results

Here we report preliminary results for 21 patients (66.7% CD and 33.3% UC) recruited so far. VDZ was administered every 4 weeks (n = 3) and 8 weeks (n = 18). VTL measurement was performed at baseline (3.8%), induction therapy (28.2%) and maintenance therapy (67.9%) in 101 samples. None of the patients developed antibodies against VDZ. Median VTL was 9.1 µg/ml (range, 0–72.3). The median VTL during induction was significantly higher 32.4 µg/ml (IQR: 13.8, 43.1) vs. 8.2 µg/ml (IQR: 6.3, 16.2) during maintenance (p < 0.0001), therefore, all analyses accounted for this effect. Median VTL was higher in patients who received VDZ every 4 vs. 8 weeks (11.9 µg/ml vs. 8.0 µg/ml, respectively; p = 0.182). Significant inverse correlations between CRP and VTLs, and between VTL and platelets were observed during maintenance (Spearman Rho −0.27, p = 0.03; Spearman Rho −0.40, p < 0.001, respectively). A high statistically significant inverse correlation between VTLs and GOT/GPT was noted in the UC group (Spearman Rho −0.79; p < 0.0001). There were no significant differences between median VTLs and the rest of analytical variables tested (haemoglobin, leucocytes, albumin, ESR and creatinine).

Conclusion

VTL are in line with those reported in other studies. Low CRP and platelets which are related with less disease are significantly associated with higher VTL.