Issue: August 2024
Fact checked byHeather Biele

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June 24, 2024
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Higher adalimumab concentration linked to complete healing in perianal fistulizing Crohn’s

Issue: August 2024
Fact checked byHeather Biele
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Key takeaways:

  • Patients with an adalimumab concentration of at least 12.1 µg/mL achieved a higher rate of healing.
  • Higher albumin levels also were associated with complete fistula healing.

An adalimumab concentration threshold of 12.1 µg/mL “may be a target for therapeutic drug monitoring” to achieve complete fistula healing in perianal fistulizing Crohn’s disease, according to research in Clinical Gastroenterology and Hepatology.

“Patients with perianal fistulizing CD are hard to treat and there are limited pharmacological options, mostly including anti-tumor necrosis factor therapy such as infliximab and adalimumab,” Konstantinos Papamichail, MD, PhD, assistant professor of medicine at Harvard Medical School and Beth Israel Deaconess Medical Center, told Healio. “Therapeutic drug monitoring is a useful tool to optimize anti-TNF therapy and achieve favorable clinical outcomes. However, there is only limited data regarding the association of adalimumab concentration and outcomes in patients with perianal fistulizing CD, while the optimal adalimumab concentration threshold to target for fistula healing is largely unknown.

Konstantinos Papamichail, MD, PhD

“This is clinically important as drug concentration cut-offs are used in reactive and proactive therapeutic drug monitoring algorithms to define therapeutic drug concentrations,” he added.

In a retrospective, multicenter study, Papamichail and colleagues enrolled 183 patients (median age at diagnosis, 23 years; 57% men) with perianal fistulizing CD, of whom 82% had complex perianal fistulizing CD and 55% were previously biologic naïve. The median adalimumab concentration was 8.5 µg/mL.

The primary outcome was complete fistula healing, with researchers aiming to identify an optimal adalimumab concentration threshold associated with this outcome.

According to study results, 35% of patients achieved complete fistula healing and had higher adalimumab concentrations compared with those who did not achieve complete healing (12.9 µg/mL vs. 6.1 µg/mL). The optimal concentration threshold associated with complete healing was 12.1 µg/mL (AUC = 0.757; 95% CI, 0.686-0.827), with sensitivity, specificity, positive predictive value and negative predictive value of 61%, 82%, 64% and 80%, respectively.

Patients with an adalimumab concentration of at least 12.1 µg/mL achieved a higher rate of healing compared with those who had a concentration of less than 12.1 µg/mL (64% vs. 20.5%), with researchers reporting that this threshold was “independently associated” with complete fistula healing (OR = 5.7; 95% CI, 2-16.1).

In addition, multivariable binary logistic regression analysis showed that higher albumin levels (OR = 3.771; 95% CI, 1.058-13.447) and adalimumab concentration (OR = 1.089; 95% CI, 1.02-1.163) also were associated with complete healing.

“Higher adalimumab concentrations are associated with complete fistula healing,” Papamichail told Healio. “An adalimumab concentration threshold of 12.1 g/mL may be a target for therapeutic drug monitoring to achieve complete fistula healing.”

He continued: “Prospective studies are needed to confirm these results. Moreover, a randomized controlled trial comparing proactive therapeutic drug monitoring with standard of care in patients with perianal fistulizing CD treated with adalimumab would be of great value.”