Appropriate Proactive Therapeutic Drug Monitoring

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.


Gold Medal Winner: Infliximab (anti-TNF competition)

According to a recent retrospective study, (S Singh et al. Clin Gastroenterol Hepatol 2016; 14: 1120-29), infliximab outperformed its rivals.  In the spirit of the recent olympics, we’ll give infliximab a gold medal in the anti-TNF category.

Here’s the play-by-play:

This study used an administrative claims database with more than 100 million US enrollees.  In total, there were 3205 biologic-naive patients with Crohn’s disease (CD) with a mean age of 41 years.  All of the participants had not received a biologic agent for at least 12 months prior to their first study dose (between 2006-2014). In addition, the authors excluded patients who had a concomitant diagnosis which could necessitate a biologic, including rheumatoid arthritis, ankylosing spondylitis, and psoriasis.

Race details:

  • Compared to adalimumab-treated patients, inlfiximab-treated patients had a lower risk of CD-related hospitalization (aHR [adjusted Hazard Ratio] 0.80), abdominal surgery (aHR 0.76), and corticosteroid use (aHR 0.85)
  • Compared to certolizumab pegol-treated patients, infliximab-treated patients had a lower risk of hospitalization (all-cause) (aHR 0.70), and CD-related hospitalization (aHR 0.59).
  • All agents had comparable risk of serious infections

Post-race analysis:

Was this a fair race (ie study)? Definitely.  If anything, this study may have underestimated the benefit of infliximab.  Due to trouble with confounders across retrospective studies, it may be that infliximab was chosen preferentially among sicker patients.

My take: There is limited data on comparative effectiveness of anti-TNF agents.  This retrospective study  indicates that infliximab is likely superior to its competitors.  Definitive proof would necessitate a head-to-head live-action (prospective) competition.

Related blog posts:

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What We Know Now: Therapeutic Drug Monitoring for Inflammatory Bowel Disease

This blog has discussed the utility of obtaining drug levels for both biologic agents and thiopurines.  A recent article (Inflamm Bowel Dis 2015; 21: 182-97) provides a concise up-to-date review.

Here are the key points:

  • Primary nonresponse to anti-TNF therapy (PNR) “is most commonly defined as lack of improvement of clinical signs and symptoms after the induction phase leading to discontinuation of the drug.”
  • “We think that patients who respond but fail to achieve remission…are likely almost all due to insufficient drug.”
  • Table 2 provides a list of predicting factors, both negative and positive, for PNR.  This list includes genetic mutations (e.g.. IL23R, NOD2/CARD15 variant), mucosal gene expression, clinical factors (e.g. young age, isolated colitis, smoking, nonstricturing disease, concomitant immunomodulators) and serologic (eg. CRP, hemoglobin, and presence of pANCA).
  • Patients with PNR to a TNF antagonist, “despite therapeutic concentrations of drug and no anti-drug antibodies (ADA), would likely benefit from a switch to an alternative drug with a different mechanism of action.”
  • “Patients with a high baseline inflammatory load…and increased clearance of drug because of a high turnover would likely benefit from higher induction doses.”  This hypothesis has been proven in rheumatoid arthritis patients in which patients with high TNF concentrations had a clinical response to 10 mg/kg that was “significantly better than the response to 3 and 6 mg/kg of infliximab.”
  • Patients (with ADA) with an “early immunogenic response against the TNF antagonist are unlikely to respond to dose escalation and thus should be switched to another TNF antagonist, and it should be considered to give higher induction doses in combination with an IMM [immunomodulator] to reduce the risk of immunogenicity.”

Take-home message: New definition of primary nonresponse to anti-TNF agent: “a lack of improvement of objectively assessed signs of active inflammation at baseline, after the induction phase despite the presence of adequate concentrations of drug and the absence of anti drug antibodies.”

Also noted: “Surgical management of ulcerative colitis in the era of biologicals” Inflamm Bowel Dis 2015; 21: 208-10. Key point: “Sacrificing the non responsive diseased colon is an underused or unnecessarily delayed chance to normalize and life.”  “Deconditioning of patient with unreasonably long escalations of ineffective medications adds to the morbidity of surgical intervention.”

“Automimmune Features are Associated with Chronic Antibiotic-refractory Pouchitis”Inflamm Bowel Dis 2015; 21: 110-20. Key point: “Microsomal antibody expression and elevated IgG4-positive plasma cell infiltration were independent risk factors” for chronic antibiotic-refractory pouchitis.”

Update on MOC (recent blog:Resistance to Maintenance of Certification | gutsandgrowth) American Board of Internal Medicine “We Got It Wrong” “We launched programs that weren’t ready and we didn’t deliver an MOC program that physicians found meaningful. We want to change that.”

Related blog posts:

EXTEND & MUSIC: Optimizing Crohn Disease Care

As noted in recent posts (see links below), there is increased interest in showing direct mucosal healing and achieving optimal drug levels in controlling Crohn disease (CD).

  1. Clin Gastroenterol Hepatol 2014: 12: 414-422.
  2. Clin Gastroenterol Hepatol 2014: 12: 423-431.

The first study examines the rates of deep remission induced by adalimumab.  Deep remission is “defined as the absence of mucosal ulceration and CD Activity Index scores less than 150.”

Design: The data is derived from the EXTEND (EXTend the Safety and Efficacy of Adalimumab Through ENDoscopic Healing) trial.  EXTEND was a 52-week randomized, double-blind, placebo-controlled trial of adalimumab (ADA) for adults (n=135) with moderate to severe ileocolonic CD.  All patients received open-label induction with ADA (160/80 mg at weeks 0/2), then were randomized to ongoing ADA 40 mg every other week or placebo.

Results: Rates of DR were 16% in ADA patients compared with 10% of placebo-treated patients at week 12.  By week 52, 19% of ADA patients were in DR compared with 0% of placebo-treated patients.

Key findings:

  • Analysis showed that shorter disease duration was associated with DR.  One-third of patients with CD for <2 years achieved DR.
  • Patients with DR had better outcomes than those with only mucosal healing (n=8); those with isolated clinical remission (n=19, no mucosal healing), but not DR, had similar outcomes to those with DR.  The associated editorial (pg 432) notes “symptoms will still make patients go to the emergency department, or miss work, or feel miserable, regardless of how good their mucosa looks.”
  • The authors state that during the 40 weeks after early CR, “estimated savings were $6117 for direct medical costs and $4243 for indirect costs” (total $10,360).  This monetary savings may not be offset in clinical practice by ileocolonoscopy which is not only invasive but also expensive.

Conclusion (from the authors): “Before any recommendation to adopt DR as a treatment target, establishing a clear association between achievement of DR and better long-term prognosis is necessary.”  The editorial advises against adopting DR as a treatment goal: “combining symptoms and mucosal healing into 1 end-point should be reconsidered as a measure of response to anti-inflammatory therapies.”

The second study, referenced above, examined plasma concentrations of certolizumab pegol (CZP) and endoscopic outcomes of patients with Crohn disease.

Design: The authors analyzed data (post hoc analysis) from the MUSIC (The Endoscopic MUcoSal Improvement in Patients with Active CD Treated with CZP) study. Adult patients received subcutaneous CZP (400 mg) at weeks 0, 2, and 4 followed by every 4 week treatment for 52 weeks.  Endoscopic evaluation took place at weeks 0, 10, and 54 and CZP concentrations were measured at weeks 8 and 54. At week 10, there were 45 patients analyzed and at week 54, 18 patients.

Key findings:

  • Mean CZP concentrations: 11.1 mcg/mL at week 8 (4 weeks after previous dosing) and 14.9 mcg/mL at week 54 (2 weeks after previous dosing).
  • Higher CZP concentration (by quartile values) correlated with endoscopic response (P=.0016) and remission (P=.0302) at week 10.
  • Among those with the highest CZP values, their 8-week CDEIS (CD Endoscopic Index of Severity) remission rate was 75% (12/16).  Overall, CDEIS remission was noted in 56% (25/45) at week 8.
  • At week 54, endoscopic remission correlated with plasma CZP values (P=.0206).
  • Both high CRP and high body weight inversely correlated with CZP concentrations.

Conclusion from this study: As with other anti-TNF agents, higher serum levels were associated with mucosal healing.  However, the data do not prove causality.  “It is possible that higher trough concentrations at week 8 may be a consequence of mucosal healing” rather than the reverse.

Bottomline: These two studies together show that achieving optimal long-term response correlates with therapeutic drug levels and mucosal healing.  At the same time, these studies along with many other indicate that we have along way to go in order for us to achieve these objectives consistently.

Related blog posts:


Anti-TNF therapy for IBD

In the same issue as the vedolizumab phase 3 studies, there is a succinct review of tumor necrosis antagonist therapy (anti-TNF) therapy for IBD (NEJM 2103; 369: 754-62).

Useful points about IBD:

  • Prevalence of ulcerative colitis (UC) and Crohn’s disease (CD) in North America: 780,000 and 630,00 respectively
  • In first 10 years of CD, cumulative rate of surgery is 40-55%.
  • In first 20 years of UC, rate of colectomy is ~15%.
  • “Recent meta-analysis do not indicate that this drug (mesalamine) has any clinically relevant efficacy in patients with” Crohn’s disease.

Anti-TNF agents:

  • Agents for IBD include infliximab, adalimumab, certolizumab pegol, and golimumab.
  • No head-to-head comparisons have been studied, though the “clinical trials suggest similar efficacy among the available drugs.”
  • Newest approved anti-TNF is golimumab which is administered subcutaneously at a dose of 200 mg at week 0, followed by 100 mg at week 2 and then 100 mg every 4 weeks.
  • A “considerable number of patients with Crohn’s disease (10-40%, depending on selection criteria) do not have a clinically relevant response to currently available TNF inhibitors (primary treatment failure) and among patients with ulcerative colitis, this proportion may be as high as 50%.”
  • “In addition, only about one third to one half of patients with Crohn’s disease have a complete remission, and about two thirds of patients do not have a response that is sustained during 12 months of continuous treatment (secondary treatment failure).”  Many of these patients will respond to dose escalation.
  • The “annual projected cost of each biologic agent for a 70-kg patient with inflammatory bowel disease is approximately $19,000 in the first year and $15,000 in subsequent years.”  These figures exclude the costs associated with administration and dose escalation.

Areas of uncertainty according to the authors:

  • “The value of concomitant treatment with immunosuppressive agents and TNF inhibitors has been debated intensely.”  Combination therapy results in superior efficacy and lower rates of antibodies to anti-TNF agents.  However, “the benefit of combined treatment for more than 12 months is uncertain.”
  • “There are no data to confirm that it (top-down treatment) is actually superior to conventional step-up therapy in terms of disease progression”

Related blog links: