P051 REAL WORLD EXPERIENCE IN THERAPEUTIC DRUG MONITORING IN INFLAMMATORY BOWEL DISEASE PATIENTS ON USTEKINUMAB

Abstract

Current evidence supports the use of reactive therapeutic drug monitoring (TDM) to guide treatment changes in inflammatory bowel disease (IBD) patients treated with anti-TNF agents. However, there is less data available on the utility of drug monitoring with ustekinumab (UST). To determine if trough levels of UST have an impact on treatment based on clinical, laboratory, and endoscopic findings. A total of 55 UST trough levels were collected from 46 patients with Crohn disease seen at our IBD center from May 2017 to June 2018. Levels were checked either reactively due to ongoing clinical symptoms, endoscopic, biologic markers (fecal calprotectin, ESR, CRP), or radiologic studies suggestive of active disease; or drawn proactively to guide de-escalation of disease therapy. Demographic data was collected including gender, medications, age, disease duration, BMI and ethnicity. Inflammatory markers (ESR, CRP), vitamin D, clinical scoring (HBI), endoscopic and histologic data were obtained within 6 months prior to level being drawn, and at 6 month follow up. Low drug levels were defined as UST trough level less than 5ug/mL. Of 45 trough levels drawn reactively, 71% were low; of 10 drawn proactively, 90% were low. There were 34 patients who had 41 low UST trough levels. These patients were more likely to be female, (64%, p=0.002), Caucasian (90%, p= 0.002), non obese (BMI≤30) (78%, p=0.001), and less likely to be on dual biologic therapy (35%, p=0.001), immune modulator (22%, p=0.002), or steroids(37%, p=0.01). Compared to patients with high UST levels, those with low levels were more likely to have higher inflammatory markers, ESR 24.9 vs 20.4, p=0.01, and CRP 22.1 vs 4.1, p=0.003. There was no significant difference in vitamin D, clinical, endoscopic, or histologic remission between patients with low and high trough levels, however only 38% had clinical scoring at the time of the drug level and 16% endoscopy/histology. Of the 41 patients with levels drawn reactively, 8 had follow up trough level after dose adjustement. All except one had improvement in drug level, however 88% remained subtherapeutic. There was endoscopic follow up in 19 of 41 patients with levels drawn reactively; 70% had low levels and 53% had endoscopic improvement or remained in remission/mild disease. The majority of patients who had drug levels checked either reactively or proactively had subtherapeutic levels. Low drug levels were associated with higher inflammatory markers. Although there was no difference in endoscopic remission seen between patients with low and high trough levels, over half of patients who had levels checked reactively and endoscopic follow up, improved or remained in remission/mild disease activity. This suggests that there may be utility to TDM to optimize drug levels and improve outcomes in patients on UST therapy.View Large Image Figure ViewerDownload Hi-res image Download (PPT)