Soluble Mucosal Addressin Cell Adhesion Molecule 1 and Retinoic Acid are Potential Tools for Therapeutic Drug Monitoring in Patients with Inflammatory Bowel Disease Treated with Vedolizumab: A Proof of Concept Study.

BACKGROUND AND AIMS: Vedolizumab [VDZ], a humanized monoclonal antibody targeting α4ß7 integrin, is effective in induction and maintenance therapy in patients with inflammatory bowel disease [IBD] who have not adequately responded to standard therapies, and high vedolizumab trough levels [VTLs] have been associated with clinical remission. The α4ß7 integrin binds to endothelial MAdCAM-1 and is upregulated by retinoic acid [RA]. The aim of this study was to determine the relationships between soluble MAdCAM-1 [sMAdCAM-1] and RA concentrations during clinical remission with VDZ maintenance therapy. METHODS: In a retrospective study performed in IBD patients treated with VDZ, we measured VTL, sMAdCAM-1 and RA concentrations. RESULTS: Among the 62 included patients [38 Crohn's disease], 24 relapsed and 38 stayed in remission from Weeks 10 to 30 after VDZ initiation. During this maintenance therapy, the median values of VTLs and RA were 15.4 µg/mL and 0.97 ng/mL, respectively, whereas sMAdCAM-1 was undetectable [<0.41 ng/mL] in 67.3% of samples. The positive predictive value [PPV] of undetectable sMAdCAM-1 for clinical remission was 80.0%, with a corresponding sensitivity of 74.6%. On multivariate analysis, undetectable sMAdCAM-1 and high VTLs [>19 µg/mL] were independently associated with clinical remission [OR = 7.5, p = 0.006 and OR = 2.2, p = 0.045, respectively]. The combination of sMAdCAM-1 < 0.41 ng/mL and VTL > 19 µg/mL was the best pharmacokinetic profile, with a PPV of 95.2%. Median values of sMAdCAM-1 and RA were significantly higher [p = 0.0001] before VDZ therapy than during the follow-up [sMAdCAM-1: 40.5 vs < 0.41 ng/mL; RA: 1.7 vs 0.97 ng/mL]. Only RA > 1.86 ng/mL before VDZ therapy was predictive of clinical remission during the follow-up (Area Under a Receiver Operating Characteristic curve [AUROC] = 80.7%). CONCLUSIONS: Undetectable sMAdCAM-1 appears strongly associated with clinical remission during VDZ maintenance therapy. Combination of undetectable sMAdCAM-1 with high VTL is also potentially interesting for therapeutic drug monitoring. Baseline RA concentrations are predictive of clinical remission. These findings need to be confirmed in further prospective studies.

Association Between Low Trough Levels of Vedolizumab During Induction Therapy for Inflammatory Bowel Diseases and Need for Additional Doses Within 6 Months.

BACKGROUND & AIMS: We investigated whether serum trough levels of vedolizumab, a humanized monoclonal antibody against integrin α4ß7, during the induction phase of treatment can determine whether patients will need additional doses (optimization of therapy) within the first 6 months. METHODS: We conducted an observational study of 47 consecutive patients with Crohn's disease (CD; n = 31) or ulcerative colitis (UC; n = 16) who had not responded to 2 previous treatment regimens with antagonists of tumor necrosis factor and were starting therapy with vedolizumab at 2 hospitals in France, from June 2014 through April 2016. All patients were given a 300-mg infusion of vedolizumab at the start of the study, Week 2, Week 6, and then every 8 weeks; patients were also given corticosteroids during the first 4-6 weeks. Patients not in remission at Week 6 were given additional doses of vedolizumab at Week 10 and then every 4 weeks (extended therapy or optimization). Remission at Week 6 of treatment was defined as CD activity score below 150 points for patients with CD and a partial Mayo Clinic score of <3 points, without concomitant corticosteroids, for patients with UC. Blood samples were collected each week and serum levels of vedolizumab and antibodies against vedolizumab were measured using an enzyme-linked immunosorbent assay. Median trough levels of vedolizumab and interquartile ranges were compared using the nonparametric Mann-Whitney test. The primary objective was to determine whether trough levels of vedolizumab measured during the first 6 weeks of induction therapy associated with the need for extended treatment within the first 6 months. RESULTS: Based on response to therapy at Week 6, extended treatment was required for 30 of the 47 patients (23 patients with CD and 7 patients with UC). At Week 2, trough levels of vedolizumab for patients selected for extended treatment were 23.0 µg/mL (interquartile range, 14.0-37.0 µg/mL), compared with 42.5 µg/mL in patients who did not receive extended treatment (interquartile range, 33.5-50.7; P = .15). At Week 6, trough levels of vedolizumab <18.5 µg/mL were associated with need for extended therapy (100% positive predictive value, 46.2%; negative predictive value; area under the receiver operating characteristic curve, 0.72) within the first 6 months. Among patients who required extended treatment at Week 10, all of those with trough levels of vedolizumab <19.0 µg/mL at Week 6 had achieved clinical remission 4 weeks later (secondary responders). CONCLUSIONS: In a prospective study of patients with CD or UC receiving induction therapy with vedolizumab, low trough levels of vedolizumab at Week 6 (<19.0 µg/mL) are associated with need for additional doses (given at Week 10 and then every 4 weeks). All patients receiving these additional doses achieved a clinical response 4 weeks later.