Trough Concentration Response in Infliximab and Adalimumab Treated Children With Inflammatory Bowel Disease Following Treatment Adjustment: A Pharmacokinetic Model.

OBJECTIVES: In patients with inflammatory bowel diseases (IBD), data on trough concentration (TC) response to adjustments of anti-tumor necrosis factor (TNFα) are scarce. METHODS: We included pediatric patients with IBD who were treated with anti-TNFα agents and had sequential monitoring of TC pre- and post-adjustment. Patients with positive anti-drug-antibodies or with concomitant change in immunomodulatory treatment were excluded. RESULTS: For the entire cohort (86 patients), median age at diagnosis was 13.2 (interquartile range, 10.7-14.9) years [females, 48%; Crohn disease (CD), 72%]. For infliximab, 58 patients had 201 interval changes and 26 had dose increase. Increase in TC following dose increase could not be predicted due to significant variability (P = 0.9). For every 10% decrease in interval, TC was increased by 1.6 µg/mL or by 57.2% (P = 0.014). Perianal disease was associated with attenuated response. For every 10% increase in interval, TC was decreased by 0.66 µg/mL or by 4.2%. The diagnosis of CD was associated with reduced response to interval increase. For adalimumab, 28 patients had 31 and 12 events of interval decrease or increase, respectively. Interval decrease resulted in increased median TC from 4.5 (3.5-5.3) µg/mL to 8.1 (6.5-10.5) µg/mL (X1.8) while interval increase resulted in TC change from 15.5 (12.8-18.6) µg/mL to 9.7 (6.5-14.6) µg/mL (:1.6) (P < 0.001 for both). Increase in delta TC was associated with younger age, and with absence of perianal disease (P = 0.001). CONCLUSION: Changes in TC following treatment adjustment can be almost linearly predicted for adalimumab while response to infliximab adjustment are more variable.

Pediatric inflammatory bowel disease: Fecal calprotectin response to Anti-tumor necrosis factor alpha.

BACKGROUND: Fecal calprotectin (FC) is a marker of mucosal inflammation in inflammatory bowel disease (IBD). We aimed to assess the effect of anti-tumor necrosis factor alpha (TNFα) therapy on FC levels in children with IBD. METHODS: The medical records of pediatric patients treated with anti-TNFα agents (2015-2020) were reviewed retrospectively. 63 patients had FC levels measured prior to anti TNFα induction with sequential measurements during follow-up. The main outcome measures were time to FC response according to cutoffs of 250, 150, 100 and 50 µgr/gr. RESULTS: Mean age was 13.6 ± 3 years [females 28 (44.4%), Crohn's 55 (87%)]. Outcomes of < 250, < 150, < 100 and < 50 µgr/gr were achieved by 52 (82%), 51 (81%), 44 (70%) and 32 (50%), respectively. The median time for achieving these cutoffs was 4.8 (1.8-15.6), 7.9 (2.6-16.4), 10.0 (3.5-20.5) and 18.5 (7.0-64.7) months, respectively. Shorter time from diagnosis to treatment was associated with achievement of FC < 50 µgr/gr (p = 0.03). There was no association between age, disease type, anti-TNFα type, inflammatory markers, disease activity indices at baseline and induction anti-TNFα trough concentration and FC response. CONCLUSIONS: FC response was achieved by the majority of patients treated with anti-TNFα within a short period of time. FC normalization in responders required almost one year. IMPACT: Fecal calprotectin response was achieved by the majority of pediatric patients within a relatively short period of time after anti-TNFα induction and maintenance therapy. Fecal calprotectin normalization required an average period of approximately one year in responders. The faster response of fecal calprotectin is associated with shorter time from diagnosis to anti-TNFα treatment. Inflammatory bowel disease treating physicians should be aware of the relatively prolonged time to fecal calprotectin normalization and to allow enough time for anti-TNFα therapy to express its full potential prior to significant interventions.

High anti-TNFα Concentrations Are Not Associated With More Adverse Events in Pediatric Inflammatory Bowel Disease.

ABSTRACT: Anti-tumor necrosis factor alpha (anti-TNFα) therapy is commonly used to treat refractory pediatric inflammatory bowel disease (IBD) and carry risks for adverse events. We aimed to assess the relationship between anti-TNFα trough concentrations and adverse events rate among pediatric patients with IBD. The medical records of pediatric patients with IBD who were treated with anti-TNFα agents from 2015 to 2020 and had sequential monitoring of trough concentration (TC) were reviewed retrospectively for the presence of adverse events. The study cohort included 135 eligible patients (59 [43.7%] girls, mean age at diagnosis 12.9 [±3] years, 111 [82.2%] Crohn disease) who had 1589 measurements of TCs (1037 [63%] infliximab). During a median follow-up period of 1.7 years (IQR 1.1-2.7), we recorded 156 adverse events in 50 patients (37%). Higher TCs were not associated with higher rate of anti-TNFα-related adverse events whereas these events (excluding increase in liver transaminases) were associated with younger age.