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Appropriate Proactive Therapeutic Drug Monitoring

September 6, 2019 7:00 am

This blog post and tomorrow’s post highlights two articles on proactive therapeutic drug monitoring (pTDM) for inflammatory bowel disease. The first article (K Papmichael et al. Clin Gastroenterol Hepatol 2019; 17: 1655-68) summarizes a meeting of 13 international IBD specialists who reached consensus on 24 statements after a review of the literature.

Full Text Link: Appropriate Therapeutic Drug Monitoring of Biologic Agents for Patients With Inflammatory Bowel Diseases

Key Recommendations:

For anti-tumor necrosis factor (anti-TNF) therapies, proactive TDM was found to be appropriate after induction and at least once during maintenance therapy, but this was not the case for the other biologics.
Reactive TDM was appropriate for all biologic agents both for primary non-response and secondary loss of response

Background/Rationale for pTDM:

“Numerous studies have demonstrated a positive correlation between serum biologic drug.concentrations and favorable therapeutic outcomes”
“Low or undetectable drug concentrations can lead to immunogenicity and treatment failures”
“TDM…is an important tool for optimizing biologic therapy…Data suggest that pTDM, with drug titration to a target trough concentration, performed in patients with clinical response/remission can also improve the efficacy of anti-TNFs”

Table 4 Scenarios of Applying Therapeutic Drug Monitoring of Biological Therapy in Patients With Inflammatory Bowel Disease

1-4: Anti-TNFs:

It is appropriate to order drug/antibody concentration testing in responders at the end of induction for all anti-TNFs.
It is appropriate to order drug/antibody concentration testing at least once during maintenance for patients on all anti-TNFs.
It is appropriate to order drug/antibody concentration testing of anti-TNFs at the end of induction in primary non-responders.
It is appropriate to order drug/antibody concentration testing for all anti-TNFs in patients with confirmed secondary loss of response.

5-8: Vedolizumab -agreement only on ordering TDM in non-responders or those with loss of response

9-12: Ustekinumab -agreement only on ordering TDM in non-responders or those with loss of response

From Table 5: Biological Drug Concentrations and Anti-Drug Antibodies When Applying Therapeutic Drug Monitoring in Inflammatory Bowel Disease

Infliximab: 15. In the presence of adequate trough drug concentrations, anti-drug antibodies are unlikely to be clinically relevant.
Infliximab: 19. The minimal trough concentration for infliximab post-induction at week 14 should be greater than 3 μg/mL, and concentrations greater than 7 μg/mL are associated with an increased likelihood of mucosal healing.
Adalimumab: 22. The minimum drug concentration at week 4 for adalimumab should at least be 5 μg/mL. Drug concentrations greater than 7 μg/ml are associated with an increased likelihood of mucosal healing.
Certolizumab: 24 & 25: The minimum concentrations for certolizumab pegol at week 6 should be greater than 32 μg/mL and 15 μg/mL during maintenance.
Golimumab 26 & 27: The minimum drug concentration at week 6 for golimumab should at least be 2.5 μg/mL and 1 μg/mL.during maintenance

My take: This article provides extensive literature to reinforce their recommendations. Most of the trough levels mentioned are minimum levels that need to be achieved.