Circulating Interleukin 6 and Albumin, and Infliximab Levels Are Good Predictors of Recovering Efficacy After Dose Escalation Infliximab Therapy in Patients with Loss of Response to Treatment for Crohnʼs Disease

We aimed to clarify the efficacy, safety, and factors associated with remission on dose escalation in patients with Crohn's disease showing loss of response (LOR) to infliximab treatment of 5 mg/kg at 8-week intervals in a clinical trial.Thirty-nine patients with LOR to 5 mg/kg infliximab therapy started treatment with 10 mg/kg per 8 weeks. LOR was defined as both a Crohn's Disease Activity Index of ≥175 at 8 weeks after infusion of 5 mg/kg infliximab and a Crohn's Disease Activity Index increase of ≥50 from 4 to 8 weeks after infusion.At week 8 after the first infusion of 10 mg/kg, median (95% confidence interval) reduction in Crohn's Disease Activity Index of 33 patients evaluated was 95.0 (70.0-134.0), meeting the primary endpoint. Remission rate at week 40 was 41% (16 of 39), with correlation noted between remission achievement and serum infliximab level (P = 0.036). Univariate analysis revealed that "infliximab trough level ≥1 µg/mL," "interleukin 6 level ≤2.41 pg/mL," and "albumin level ≥3.8 g/dL" before dose escalation were significantly associated with remission at week 40 (P = 0.017, P = 0.011, and P = 0.019, respectively), and these variables were correlated with each other (all: P < 0.001). The cutoff infliximab level for remission was 0.42 µg/mL in receiver operating characteristic curve analysis. No adverse events related to dose escalation were observed.Doubling the infliximab dose safely led to remission in patients with Crohn's disease with LOR to 5 mg/kg treatment. Remission was associated with pre-escalation levels of infliximab, interleukin 6, and albumin. Our findings suggest that dose escalation while maintaining a certain level of infliximab is important in achieving remission.