RBC MTXPG1–5 were measured using high-performance

liquid chromatography. Clinical status (active disease or remission) was assessed by 2 IBD physicians blinded to [MTXPG], using combination of prospectively recorded clinical activity indices (Simple Colitis Activity Index, Harvey Bradshaw Index), endoscopy, fecal calprotectin and C-reactive protein (CRP). Pearson correlation coefficient, r was calculated to assess relationship between MTX dose and [MTXPG]. Association between [MTXPG] and clinical response was analyzed with unpaired t-test. Results: Patient demographics are shown in Table 1: Table 1. Median Age (years, range) 35 (22–59) Male, n (%) 12 (57) Crohn’s disease / ulcerative colitis n(%) / IBD-unclassified 16 (76)/3 (14)/2 (10) Disease duration Buparlisib concentration years, mean PI3K Inhibitor Library molecular weight (SD) 7.6+/–4.3 Concomitant biologic, n (none/infliximab/adalimumab) 6/12/3 MTX route administration (oral/subcutaneous) 19/2 MTX dose, mg, mean (SD) 17.2+/–1.2 4/21(22%) patients (3 of whom admitted non-adherence) had undetectable MTXPGs and were excluded from further analysis. MTXPG2–4 were detected in all

adherent patients. PG3 was the predominant polyglutamate accounting for a mean of 43% of total MTXPG. A linear relationship between dose of MTX and PG1–5 was observed. 12/21(57%) patients were assessed as having active disease. No significant difference in mean [MTXPGn] was observed between those with active disease and remission, (Table 2). For each

MTXPGn, a non-significant trend towards a higher concentration was observed in patients with active disease. Table 2 MTX PG Correlation between MTX dose and MTXPG r, (p) Active disease: [ PGn] (nmol/RBC medchemexpress 8 × 1012), mean, SD Remission [PGn] (nmol/RBC 8 × 1012) mean, SD p value PG1 0.96 (p = 0.01) 22 ± 16 15 ± 10 0.28 PG2 0.92 (p = 0.008) 24 ± 3.6 17 ± 2.3 0.17 PG3 0.98 (p = 0.003) 51 ± 9.8 36 ± 6.7 0.26 PG4 0.94 (p = 0.019) 19 ± 4.9 12 ± 1.7 0.25 PG5 0.67 (p = 0.219) 4.5 ± 1.5 1.3 ± 0.73 0.09 Conclusions: In this study, the largest to date in IBD, measuring RBC MTXPG was useful in assessing adherence to MTX. A trend towards higher PG concentrations was associated with active disease confirming the findings in the only other study in IBD. Whether this is confounded by higher doses being used in patients with more active disease warrants further study in larger, prospective trials. 1. Dervieux T et al, Annals of the Rheumatic Diseases, 2005;64:1180–1185. 2. Stamp LK et al, Arthritis Rheumatism. 2010;3:359–368. 3. Alenka JB et al. Theraputic Drug Monitoring, 2007;29:619–625. M RADOJCIC,1 F MACRAE, B VINEY Department of Colorectal Medicine and Genetics, The Royal Melbourne Hospital and The University of Melbourne Medical School, Melbourne, Australia Introduction: Up to 40% of patients with an attack of severe, acute ulcerative colitis (UC) fail to respond to intravenous corticosteroids.