P1081 Correlation of vedolizumab levels with medium-and long-term response in patients with Inflammatory Bowel Disease
Authors: Hernández-Pérez M , Suarez Ferrer C J , García-Ramírez L , MartínArranz E , SánchezAzofra M , Poza Cordón J , Rueda García J L , Martín-Arranz M D 
Published: January 2025

Abstract

Background
Drug level monitoring is standard practice for anti-TNF therapies (1,2). In the case of vedolizumab, pivotal studies suggest a similar relationship (3,4) although real-world studies are needed. This study aimed to investigate the relationship between vedolizumab levels during the induction phase and clinical response in medium and long term.

Methods
A retrospective analysis was performed on a cohort of patients diagnosed with inflammatory bowel disease who completed at least the induction phase with vedolizumab at the IBD Unit of Hospital La Paz(from January 2019 until June 2023). Drug levels during induction (week 2, 6, and 14) and medium- and long-term (24 and 54, respectively) were collected, along with clinical, biochemical, and ultrasound response variables.

Results
A total of 81 patients were included: 50.6% with ulcerative colitis (UC) and 45.7% with Crohn’s disease (CD). Drug levels at week 6 were compared between responders and non-responders at weeks 24 and 54. At week 24, levels in responders were 21.40 μg/ml (SD 14.67), and in non-responders, 15.34 μg/ml (SD 11.52) (p=0.07). At week 54, levels were 22.93 μg/ml (SD 13.44) in responders and 17.85 μg/ml (SD 12.46) in non-responders (p=0.17). At week 14, levels in CD (12.91 μg/ml; SD 11.88) and UC (10.23 μg/ml; SD 7.40) groups showed no significant differences (p=0.27). In CD patients in clinical remission at week 24, levels were 17.13 μg/ml (SD 12.97) vs 12.07 μg/ml (SD 11.61) in non-remission patients (p=0.29). In UC patients, levels at week 14 were 9.37 μg/ml (SD 7.61) in those in remission at week 24, versus 9.15 μg/ml (SD 5.89) in non-remission patients (p=0.93). At week 6, levels in patients with biochemical remission at week 24 (&lt;150 μg/g) were 21.40 μg/ml (SD 15.42), compared to 15.34 μg/ml (SD 10.70) in non-remission patients (p=0.07). Ultrasound was performed on 12 CD patients at week 54, with the following mean scores: Simple-US score 7.22 (SD 1.72), SUS-CD 7.95 (SD 13.72), IBUS-SAS 41.71 (SD 18.49), and BUSS 5.38 (SD 1.19). Covariates influencing drug levels included baseline disease activity markers such as albumin (p=0.00) and fecal calprotectin (p=0.00), as well as intensification of the maintenance schedule (every 4 weeks, p=0.001). Other factors, such as IBD type, prior anti-TNF treatment, or previous surgeries, did not show relationship with drug levels at follow-up.

Conclusion
Currently, there is insufficient evidence to support the routine monitoring of vedolizumab levels for optimizing therapeutic outcomes. However, our results suggest that higher levels at week 6 may be associated with a better clinical response at week 54. Additionally, baseline markers of disease activity, such as fecal calprotectin and albumin, influence long-term drug levels.

References
1.Papamichael K, Vande Casteele N, Jeyarajah J, Jairath V, Osterman MT, Cheifetz AS. Higher Postinduction Infliximab Concentrations Are Associated With Improved Clinical Outcomes in Fistulizing Crohn’s Disease: An ACCENT-II Post Hoc Analysis. Am J Gastroenterol [Internet]. 2021 May 1 [cited 2024 Oct 21];116(5):1007–14. Available from: https://pubmed.ncbi.nlm.nih.gov/33929379/2.
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