Objective: Infliximab (IFX) concentrations are a predictive factor (PF) of pharmacokinetic (PK) origin in the treatment of Crohn’s disease (CD). We evaluated clearance, another PF of PK origin, either alone or in combination with concentrations. Methods: PF of PK origin were evaluated from two cohorts, the first received standard dosing (n=37), and the second was designed to proactively target therapeutic IFX concentrations (n=108). Concentrations were measured using homogenous mobility shift assay. Clearance was estimated using nonlinear mixed effects methods with Bayesian priors. C-reactive protein based clinical remission (<3mg/L in the absence of symptoms) was used for the disease control outcome. Longitudinal changes in disease control due to factors including time, IFX concentration, and clearance were analyzed using repeated event analysis. Change in objective function value (∆OFV) was calculated to compare concentration and clearance. Results: Lower baseline clearance and proactive dosing associated with enhanced disease control during induction (p<0.01). Higher IFX concentrations and lower Clearance measured at the second, third and fourth infusion yielded improved disease control during maintenance (p<0.032). During maintenance, the association with disease control was better with clearance than with concentrations (∆OFV= -19.2; p<0.001), and the combination of both further minimized OFV (p<0.001) with markedly improved clinical yield in the presence of both PF of PK origin. Conclusion: PF of PK origin and lower clearance during induction and maintenance yielded enhanced disease control in pediatric CD treated with IFX. The combination of IFX concentration and clearance are better predictors of therapeutic outcome compared to either one alone.

An analysis of the relationship between plasma cytokines and the effectiveness of treatment with TNFαinhibitors was performed in 81 patients with moderate-to-severe psoriasis. Treatment efficacy was assessed by PASI score, and patients were classified into a positive effect (PASI≥75) and no effect group (PASI≤50). A positive effect was reached in 11 (41%) patients for etanercept, 14 (52%) for adalimumab, and 26 (96%) for infliximab. Data analysis did not show  differences in baseline TNFα levels and subsequent treatment effectiveness. The CART algorithm showed that at the baseline level of VEGF ≥ 32 pg/ml and IL17F &lt; 26 pg/ml, there was an 83% probability of a positive effect. Random forest analysis showed the importance of VEGF, ICAM1, sCD40L, IL17F and IL31 baseline levels in the prediction of treatment effectiveness.   Significant differences between the groups before/after the treatment were found only for TNFα: the median values were more than 50 times higher in no effect compared with positive effect group. There were differences before/after therapy in the levels of IL20, ICAM1, IL22, IL23 in the no effect group. The treatment affected the cytokine profile in most cases regardless of the effectiveness of therapy.