New Target Drug Levels in Inflammatory Bowel Disease

According to a recent review (Vaughn BP, Sandborn WJ, Cheifetz AS. Inflamm Bowel Dis 2015; 21: 1435-42), higher target levels of infliximab should be considered.

After reviewing the relevant studies which are summarized in Table 1, the authors state that in their experience infliximab (IFX) levels of 5 to 10 mcg/mL are desirable.  Using this standard, they note in a retrospective review that proactive testing identifies only 29% of patients in this range.

Similarly, the TAXIT study (Casteele NV et al. Gastroenterol 2015; 148: 1320-29) identified 44% of patients with a trough concentration of 3-7 mcg/mL at baseline screening.  In this study, after achieving an adequate trough concentration, they found that patients had ~70% clinical remission at 1 year.  TAXIT acronym = the Trough Concentration Adapted Infliximab Treatment trial.  The TAXIT study was a 1-year randomized control trial with 263 adults (178 with CD and 85 with UC).

Recommendations from this review:

  • When therapeutic drug monitoring is used to react to symptomatic patients (Figure 1), if they test negative for antibodies to infliximab (ATIs) and have a low IFX level, then increasing the dose is recommended.  In those with therapeutic IFX and negative ATIs, then consider change in drug class or surgery (rather than dose escalation).
  • When therapeutic drug monitoring is used to react to symptomatic patients, if they test positive for ATIs, if there is a low level ATI (<15 mcg/mL for the referenced assay), then increasing the dose is recommended, otherwise consider change in drug class or surgery (rather than dose escalation).
  • For proactive monitoring, if negative ATI, and IFX trough level is >10 mcg/mL consider extending interval.  If the IFX level is low, increase dose.  If IFX is therapeutic, continue same dose and consider re-check in 6-12 months.
  • For proactive monitoring (Figure 3), if positive ATI, the authors recommend increasing dose if faced with low level ATI and consider change in drug class or surgery (rather than dose escalation). [If someone is doing well, I would not agree with this recommendation.  I would not stop a therapy based on a single blood test.]

One more useful point:

The authors note that combination therapy improves IFX levels and lessens the likelihood of ATIs.  “Current evidence suggests that combination of an anti-TNF with an immunomodulator is the most efficacious treatment for new-onset IBD.”  They speculate that proactive monitoring may allow IFX monotherapy without the need for combination therapy or allow de-escalation of combination therapy.

Bottomline: Consider a higher infliximab target level (5-10 mcg/mL) and using proactive monitoring to achieve higher remission rates.

Related blog posts:

Cumberland Island

Cumberland Island

Briefly noted:

Casen C, et al. Aliment Pharmacol There 2015; 42: 71-83. (Thanks to Ben Gold for this reference). After studying the stool of 165 healthy controls, the authors used 54 DNA probes targeting >300 bacteria.  This genetic analysis-map dysbiosis test, subsequently analyzed 330 more patients; it confirmed dysbiosis in 73% of IBS patients, 70% of treatment-naive IBD patients and 80% of IBD patients in remission compared with 16% of healthy individuals.  Take-home point: Ultimately stool analysis could lead to more accurate evaluation and monitoring of individuals with suspected IBS or IBD.

Disclaimer: These blog posts are for educational purposes only. Specific dosing of medications/diets (along with potential adverse effects) should be confirmed by prescribing physician/nutritionist.  This content is not a substitute for medical advice, diagnosis or treatment provided by a qualified healthcare provider. Always seek the advice of your physician or other qualified health provider with any questions you may have regarding a condition.


3 thoughts on “New Target Drug Levels in Inflammatory Bowel Disease

  1. Pingback: Another Look at “Step-up” IBD Therapy | gutsandgrowth

  2. Pingback: Disease extent and need for higher infliximab dosing | gutsandgrowth

  3. Pingback: Support for Step-Up Therapy and Thiopurines | gutsandgrowth

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