Tissue exposure does not explain non-response in ulcerative colitis patients with adequate serum vedolizumab concentrations

Background and aims Some patients with ulcerative colitis (UC) do not respond to vedolizumab treatment despite adequate drug exposure in serum. This study aimed to investigate vedolizumab in tissue and questioned whether insufficient tissue exposure could explain non-response in UC patients with adequate serum vedolizumab concentrations. Methods A paired serum sample and colonic mucosal biopsy was collected from 40 UC patients (20 endoscopic responders, 20 non-responders) at week 14 of vedolizumab treatment. Vedolizumab, soluble (s)-mucosal addressin cell adhesion molecule-1 (MAdCAM-1), s-vascular cell adhesion molecule-1 (VCAM-1) and s-intercellular adhesion molecule-1 (ICAM-1) were measured in serum and/or tissue. Endoscopic response was defined as Mayo endoscopic sub-score ≤1. Results A significant positive correlation was observed between vedolizumab serum and colonic tissue concentrations (ρ = 0.84, p<0.0001), regardless of the macroscopic inflammatory state of the tissue. Vedolizumab tissue concentrations were lower in non-responders than in responders (0.07 vs 0.11 µg/mg, p = 0.04). In the subgroup of patients with adequate vedolizumab serum concentrations (>14.6 µg/mL), tissue vedolizumab was not significantly different between responders and non-responders (0.15 vs 0.13 µg/mg; p = 0.92). Serum sMAdCAM-1, but not serum sICAM-1 or sVCAM-1 concentrations, were significantly higher in responders than non-responders with adequate vedolizumab serum concentrations (1.04 vs 0.83 ng/mL, p =0.03). Conclusions Vedolizumab concentrations in colonic mucosal tissue of UC patients reflect the concentration in serum regardless of the macroscopic inflammatory state of the tissue. Our data shows that insufficient tissue exposure does not explain non-response in UC patients with adequate serum vedolizumab concentrations.

AB0390 ASSOCIATION BETWEEN INITIAL SERUM “TUMOR NECROSIS FACTOR-LIKE WEAK INDUCER OF APOPTOSIS” (TWEAK) LEVEL AND TREATMENT RESPONSE IN SYSTEMIC LUPUS ERYTHEMATOSUS (SLE) NEPHROPATHY

Background:SLE is a chronic inflammatory immunologic abnormalities disease which produce a number of antinuclear antibodies. The SLE renal involvement is clinically apparent in approximately 50% patients (Norby et al., 2017). It is very important to introduce the prompt treatment to prevent the permanent end stage renal disease.Objectives:This study aimed to identify the serum biomarkers that correlate with pretreatment disease activity in patients with SLE nephropathy and predict the treatment outcome so that we may identify the unresponsive cases and switch to the other biologic agents like anti-TWEAK monoclonal antibody in the future.Methods:This was a hospital-based prospective analytical study conducted from January 2018 to November 2019 in Rheumatology Department, Yangon Specialty Hospital. 88 SLE nephropathy patients with 24-hour urinary protein above 0.5g/day planned to have 6 months course of IV cyclophosphamide were enrolled. The paired serum sample of each patient was analyzed by ELISA twice to get the mean serum TWEAK value. Pretreatment SLE disease activity was assessed by the SLEDAI 2k. After the completion of 6 months of aggressive treatment, the treatment response was assessed by measuring the 24 hour urinary protein.Results:Among the 88 patients, 63 patients (71.6%) had completed total 6-months course and 25 patients (28.4%) had not completed:11 patients (12.5%) expired and 2 patients (2.27%) had been changed to other DMARD and 12 patients (13.63%) did not attend the follow up clinic. The mean serum TWEAK level was 856 ± 77 pg/ml in 88 patients. According to the range of serum TWEAK level, most of the patients had serum TWEAK level of 601-900 pg/ml (53.4% of the study population). There was positive correlation between pre-treatment SLEDAI 2k score and pretreatment serum TWEAK level (r=0.464 and P <0.001). When the SLEDAI 2k score was grouped into mild, moderate, high and very high disease activity, the serum TWEAK level also had positive association with the different levels of disease activity (p<0.001). Among 63 treatment completed patients, 55 patients (87.3%) were the treatment responders but 8 patients (12.7%) were treatment non-responders. There was significant difference in the pretreatment SLEDAI 2k in terms of disease activity between treatment responder and treatment non-responder (p<0.001). There was significant difference in the pretreatment SLEDAI 2k in terms of reduction in 24-hours urinary protein between treatment responder and treatment non-responder (p<0.001). There was no significant difference in the level of pretreatment serum TWEAK level between treatment responders and treatment non responders (p=1.000). There was also no significant difference in the pretreatment serum TWEAK level between treatment responders and treatment non-responders in terms of reduction in 24 hours urinary protein (p=0.804).Conclusion:Although the pretreatment serum TWEAK level had a positive correlation with pretreatment disease activity of SLEDAI 2k, it did not reflect the outcome of the responsiveness to the intensive therapy.References:[1]Norby, et al (2017) Outcome in biopsy-proven lupus nephritis: evaluation of biopsies from the Norwegian kidney biopsy registry.Lupus; 26:88Acknowledgments:Prof.Chit Soe, Prof.Hlaing Mya WinDisclosure of Interests:None declared

P464 Vedolizumab concentrations in colonic mucosal tissue of ulcerative colitis patients inversely correlate with the severity of inflammation

Background Multiple studies have reported the association between vedolizumab serum concentrations and endoscopic outcomes in patients with ulcerative colitis (UC). However, little is known about drug consumption in tissue and the relationship with mucosal inflammation. This study aimed to investigate vedolizumab concentrations in the tissue of UC patients and the correlation with their inflammatory state and serum levels. Methods A paired serum sample and colonic mucosal biopsy were collected in 36 UC patients at week 14 of vedolizumab treatment. In non-responders, defined as a Mayo endoscopic subscore of ≥2, inflamed colonic biopsies were taken in the sigmoid around 20–30 cm from the anal verge. In responders, defined as a Mayo endoscopic subscore ≤ 1, a biopsy was taken in a macroscopically uninflamed area at the same location. Biopsies were lysed by the addition of 10 μl lysis buffer (50 mM Tris, 0.1% Triton X-100 and 100 mM NaCl) per mg tissue and vortexed every 5 min during 1 h. Total protein content was measured and normalised to 3 mg/ml before analysis of the vedolizumab concentration using an in-house developed ELISA. Results are expressed as µg vedolizumab/mg total protein content. Results A positive correlation was observed between vedolizumab concentrations in tissue and serum (Spearman r = 0.8447, p &lt; 0.0001), both in inflamed (r = 0.8609, p &lt;0.0001, n = 16) and uninflamed tissue (r = 0.7925, p &lt;0.0001, n = 20). The median tissue vedolizumab concentration in patients with Mayo endoscopic subscore 0, 1, 2 and 3 were 0.120, 0.074, 0.062 and 0.064 μg/mg, respectively (p &lt; 0.01, see figure), indicating that tissue drug levels inversely correlate with the severity of inflammation. Vedolizumab tissue concentrations were significantly lower in non-responders compared with responders (0.064 vs. 0.112 μg/mg, p &lt;0.05). Moreover, patients achieving Mayo endoscopic subscore 0 had significantly higher vedolizumab levels in colonic tissue compared with patients not achieving this outcome (0.120 vs. 0.065 μg/mg, p &lt;0.02). Interestingly, a trend was observed towards higher serum-to-tissue ratios of vedolizumab in non-responders compared with responders (p = 0.0523). This finding suggests that if two patients have the same serum vedolizumab concentration, the patient with mucosal inflammation is more likely to have lower tissue levels than the patient with no or limited inflammation. Conclusion Vedolizumab concentrations in colonic mucosal tissue of UC patients inversely correlate with the severity of inflammation. As the serum-to-tissue ratio of vedolizumab is numerically higher in non-responders compared with responders, the relative distribution of vedolizumab in serum and tissue might be more important than the drug concentration alone.

Urine Concentrating Ability in Infants with Sickle Cell Anemia: Baseline Data from the BABY HUG Trial.

A urine concentrating defect is quite common in sickle cell anemia (SCA), has its onset in early childhood, and may be reversible (with transfusion) until age 10 years. BABY HUG is an NHLBI-NICHD sponsored double-blind, placebo-controlled Phase III Clinical Trial (NCT00006400) designed to assess efficacy of hydroxyurea in preventing organ damage in young children with SCA (Hb SS or SβO thalassemia); primary endpoints are spleen function and glomerular filtration rate (GFR). Two hundred thirty-three infants, recruited without regard to disease severity, underwent eligibility screening. To assess urine concentrating ability as a secondary endpoint, parents were instructed to collect and save timed urine specimens from subjects after 4 to 10 hours of fluid deprivation (NPO) overnight for osmolality (OSM) determination. More prolonged deprivation was avoided due to safety concerns. A paired serum sample for OSM, urea nitrogen (BUN), and creatinine was obtained the next morning. All specimens were analyzed in a central laboratory. The analyses included 184 infants with a urine specimen and a reported period of fluid deprivation of at least four hours; 178 had concurrent sera. Mean age was 13.0±2.7 mo (range 7.5 – 17.9 mo) and mean duration of fluid deprivation was 7.4±2.4 hr (4–13 hr). Mean serum OSM was 286±6 mOsm/kg H2O and independent of age, height, weight, or duration NPO. Urine OSM (mean 410±152, median 433, range 58–794 mOsm/kg H2O) was significantly greater than serum osmolality (p&lt;0.0001) and correlated with duration NPO (p=0.001). One hundred forty-two infants (77.2%) concentrated urine (urine OSM &gt; [mean serum OSM + 1 SD]); twenty-two (12.0%) had urine/serum OSM ratio &gt; 2 and 54 (29.4%) had urine OSM &gt; 500 mOsm/L. In addition, five infants (2.7%) were isosthenuric (urine OSM within mean serum OSM ± 1 SD) and 37 (20.1%) hyposthenuric (&gt; 1 SD below mean serum OSM) despite instructions to withhold fluid. Urine OSM was associated with increasing 99mTc-DTPA GFR (p=0.024) and BUN (p&lt;0.0001), but not with serum OSM, age, height, weight or serum creatinine. We conclude that even with a variable, often limited, fluid deprivation challenge, 75 percent of young infants with SCD were able to concentrate urine. We anticipate that at the end of each infant’s two-year study drug treatment period parents will be more successful in achieving the recommended fluid deprivation and urine collection and that differences in concentrating ability between those taking hydroxyurea and those taking placebo will be discernable.