Infliximab levels above 6.9 mg/L at week 14 predict sustained remission in pediatric IBD
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Key takeaways:
- Week 14 trough levels predicted sustained remission vs. week 6 trough levels.
- The optimal cutoff levels for predicting sustained remission were 13.2 mg/L at week 6 and 6.9 mg/L at week 14.
Infliximab concentrations above 6.9 mg/L at 14 weeks after initiation of treatment predicted sustained remission between 26 and 52 weeks in children with inflammatory bowel disease, according to researchers in the Netherlands.
“Several studies have shown that the effectiveness of infliximab can be prolonged by measuring drug levels followed by dose optimization,” Nanja Bevers, PhD, of the department of pediatrics at Zuyderland Medical Center, and colleagues wrote in Therapeutic Advances in Gastroenterology. “However, there is little agreement about the optimal time to measure infliximab levels in children to predict sustained durable remission. “
In a retrospective study, researchers enrolled 70 biologic-naive pediatric IBD patients (median age, 15.2 years; 50% girls; 89% Crohn’s disease) who initiated infliximab between March 2019 and May 2022 to evaluate whether trough levels at weeks 6 and 14 predicted sustained remission between weeks 26 and 52. The median disease duration was 5.6 months and the median infliximab dose was 5.3 mg/kg at baseline.
According to results, 69 patients reached the maintenance phase at week 14, of whom 22 missed trough-level evaluation at weeks 6 (TL6) or 14 (TL14) and were excluded. Four discontinued treatment prior to week 52. In total, 31 patients achieved sustained remission.
Median TL6 and TL14 were 15 mg/L and 5.5 mg/L, respectively, with median trough levels of 5 mg/L and 6.2 mg/L reported at weeks 26 and 52. While TL6 was “not significantly higher” among those who achieved sustained remission vs. those who did not (16.9 mg/L vs. 12 mg/L), the difference in median TL14 between groups reached significance (7.7 mg/L vs. 3.8 mg/L).
Further, area under the receiver operating curve analysis showed TL14 better predicted sustained remission vs. TL6 (AUROC = 0.75; 95% CI, 0.6-0.9 vs. AUROC = 0.67; 95% CI, 0.51-0.83). The optimal cutoff level for predicting sustained remission at TL6 was 13.2 mg/L with a sensitivity of 68%, a specificity of 69% and positive and negative predictive values of 81% and 52%, respectively. The optimal cutoff at TL14 was 6.9 mg/L with 58%, 81%, 86% and 50%.
“An exposure-response relationship of infliximab in pediatric IBD was confirmed in the current study,” Bevers and colleagues concluded. “As drug concentrations are modifiable factors in treatment effectiveness, we suggest monitoring and adjusting infliximab concentrations to improve treatment outcomes.”
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