P010 Precision Dosing Tool Forecasts Trough Infliximab and Associates With Disease Status in Inflammatory Bowel Diseases

BACKGROUND: Substantial inter- and intra-individual variability of infliximab (IFX) pharmacokinetics (PK) necessitates tailored dosing approaches. Here, we evaluated the performances of a Model Informed Precision Dosing (MIPD) Tool in forecasting trough Infliximab (IFX) levels in association with disease status and circulating TNF-α in patients with Inflammatory Bowel Diseases (IBD). METHODS: Consented patients undergoing every 8-week maintenance therapy with IFX were enrolled. Midcycle specimens were collected, IFX, antibodies to IFX, albumin were determined and analyzed with weight using nonlinear mixed effect models coupled with Bayesian data assimilation to forecast trough levels. Accuracy of forecasted as compared to observed trough IFX levels were evaluated using Demings regression. Association between IFX levels, CRP-based clinical remission and TNF-α levels were analyzed using logistic regression and linear mixed effect models. RESULTS: In 41 patients receiving IFX (median dose = 5.3 mg/Kg), median IFX levels decreased from 13.0 to 3.9 µg/ml from mid to end of cycle time points, respectively. Midcycle IFX levels forecasted trough with Deming’s slope = 0.90 and R2 =0.87. Observed end cycle and forecasted trough levels above 5µg/mL associated with CRP-based clinical remission (OR = 7.2 CI95%: 1.7-30.2; OR = 21.0 CI95%: 3.4-127.9, respectively) (p < 0.01). Median TNF-α levels increased from 4.6 to 8.0 pg/ml from mid to end of cycle time points, respectively (p < 0.01). CRP and TNF-α levels associated independently and additively to decreased IFX levels (p < 0.01). CONCLUSION: These data establish the value of our MIPD tool in forecasting trough IFX levels in patients with IBD. Serum TNF-α and CRP are reflective of inflammatory burden which impacts exposure.