Therapeutic Drug Monitoring in Perianal Fistulizing Crohn’s Disease

Perianal fistulizing Crohn's disease: Current perspectives on diagnosis, monitoring and management with a focus on emerging therapies

Crohn's disease (CD), a chronic inflammatory bowel disorder, manifests in various phenotypes, with fistulizing perianal CD (CD-PAF) being one of its most severe phenotypes. Characterized by fistula formation and abscesses, CD-PAF impacts 17% to 34% of all CD cases and with a significantly deleterious impact on patient's quality of life, while increasing the risk for anorectal cancers. The pathogenesis involves a complex interplay of genetic, immunological and environmental factors, with cytokines such as tumor necrosis factor-alpha (TNF-α) and transforming growth factor-beta (TGF-β) playing pivotal roles. Diagnostic protocols require a multi-disciplinary approach including colonoscopy, examination under anesthesia and magnetic resonance imaging. In terms of treatment, biologics alone often prove inadequate, making surgical interventions such as setons and fistula surgeries essential. Emerging therapies such as mesenchymal stem cells are under study. The South Asian context adds layers of complexity, including diagnostic ambiguities related to high tuberculosis prevalence, healthcare access limitations and cultural stigma toward perianal Crohn's disease and ostomy surgery. Effective management necessitates an integrated, multi-disciplinary approach, especially in resource-constrained settings. Despite advances, there remain significant gaps in understanding the disease's pathophysiology and a dearth of standardized outcome measures, underscoring the urgent need for comprehensive research.

Management of Perianal Fistulizing Crohn's Disease

Perianal fistulizing Crohn's disease (CD) represents a severe phenotype of CD that is associated with significant morbidity and reduction in quality of life. Perianal fistulizing CD is caused by a complex interplay of genetic predisposition, immune dysregulation, gut dysbiosis, and various unknown physiological and mechanical factors. A multidisciplinary approach is hence required for optimal management . A detailed anatomical description and classification of perianal fistula, including comprehensive clinical, endoscopic, and radiological diagnostic workup, is an important prerequisite to treatment. For simple perianal fistulas, use of antibiotics and immunomodulators, with or without fistulotomy, are appropriate measures. The medical management of complex perianal fistula, on the other hand, requires adequate control of infection before initiation of therapy with immunomodulators. In active complex perianal fistula, anti-tumor necrosis factors remain the most accepted therapy, with concomitant use of antibiotics or immunomodulators enhancing the efficacy. For patients refractory to anti-tumor necrosis factors, treatment with anti-integrins, anti-interleukins, and small molecules is being evaluated. Mesenchymal stem cells, hyperbaric oxygen therapy, and exclusive enteral nutrition have also been investigated as adjunct therapies. Despite the expansion of the medical armamentarium, a large proportion of the patients require surgical interventions. In this review, we provide an up-to-date overview of the pathophysiology, clinical presentation, diagnosis, and medical management of perianal fistulizing CD. A brief overview of the surgical management of perianal fistulizing CD is also provided.

Subcutaneous Infliximab [CT-P13], a True Biologic 2.0. Real Clinical Practice Multicentre Study

Background: Inflammatory bowel disease (IBD), including Crohn’s disease and ulcerative colitis, is characterized by chronic relapsing intestinal inflammation. There are few data on the efficacy and safety in clinical practice of infliximab (CT-P13) in subcutaneous formulation (SC) for the treatment of patients with IBD. Methods: Multicenter, prospective study of patients with IBD in clinical remission, who had their treatment changed from intravenous (IV) infliximab to SC. Two groups of patients were evaluated according to whether they were on IV infliximab treatment at standard or intensified doses before the switch. Results: A total of 30 patients were on standard dosing and another 30 in intensified therapy. Treatment persistence in both groups at 6 months was greater than 95%. In both groups after the change, neither the biomarkers of inflammation nor the activity indices underwent significant changes at 3 and 6 months compared to the baseline value. Similarly, in both groups, infliximab trough levels showed a significant increase 3 and 6 months after the change to SC. No serious adverse events were registered. Conclusions: The CT-P13 SC brings a new anti-TNF era. Achieving much higher drug levels that are constant over time opens new paths to explore the management of patients with IBD: less immunogenicity, better perianal disease control and higher achievement of mucosal healing.