Disease extent and need for higher infliximab dosing

A recent study (JM Shapiro et al. JPGN 2016; 62: 867-72) reviewed 98 pediatric patients treated with infliximab (2012-2014) with inflammatory bowel disease (IBD).

The authors divided their patients into three groups, mainly based on extent of colonic involvement.  In those with limited colonic involvement, they were labelled “limited” disease (n=53).  In those with patchy inflammation involving the entire colon, they were considered to have “moderate” disease (n=27).  In contrast, those with continuous pancolitis were ascribed to have “extensive” disease (n=18).  Overall, Crohn’s disease accounted for 85 patients (87%),  ulcerative colitis for 11 patients (11%), IBDU for 2 patients (2%).  Interestingly, the majority (9 of 11) of those patients without Crohn’s disease were considered to have extensive disease.

Key findings:

  • “Patients with moderate and extensive disease, started taking 5 mg/kg per dose, showed statistically significant shorter times to escalation that those with limited disease.”
  • 70% of those with extensive disease required dose escalation, compared with 58.3% of those with moderate disease and 26.4% of those with limited disease.
  • The authors note that patients (n=8) with extensive disease who started with 10 mg/kg dosing  “exhibited longer treatment durability;” all 8 patients who started on 10 mg/kg dosing remained on this dose at the study’s conclusion.  Among the 10 patients that started on 5 mg/kg dosing, only 7 were on IFX therapy at the study conclusion–3 remained on 5 mg/kg, 4 were escalated to 10 mg/kg; there were 3 patients who stopped IFX therapy (1 infusion reaction, 2 with nonresponse).

My take: This is a small study. Yet, the implication is that early optimal dosing of IFX is likely  helpful, especially in the setting of extensive disease.

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Best strategy for dose escalation of infliximab

At least 50% of patients with long-term infliximab therapy require dose escalation.  However, dose escalation can mean doubling the dose or shortening the infusion interval.  So which strategy is best?  A recent article provides some insight into this question (Inflamm Bowel Dis 2012; 18: 2026-33).

In this multicenter retrospective study of 168 Crohn’s disease (CD) patients, the outcome of patients who had dose-doubling (n=112) to 10 mg/kg/dose/8 weeks was compared with patients whose infusion intervals were halved to 5 mg/kg/dose/4 weeks (n=56).  The entire cohort had a mean age of 25 years and a mean disease duration of 12 years.  39% had a history of previous intestinal surgery.  Concurrent use of thiopurines was noted in 68% and concurrent use of methotrexate in 4%.

Sustained response at 1 year to dose-doubling strategy was 50% compared with 39% in the interval-halving group.  Favorable factors included nonsmoking status, normal C-reactive protein, and CD diagnosis between 16-40 years of age.

It is noted that a subsequent dose escalation was experienced by 28 of the 87 patients who had loss of response after first dose escalation.  Regained response occurred in 9 (32%) of this cohort.

The authors indicate that increasing the dose to 10 mg/kg/8 weeks is likely preferable due to convenience and cost.  At the same time, it is apparent that shortening the infusion interval is not likely to be more effective than dose doubling.

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