Implications for sequencing of biologic therapy and choice of second anti-TNF in patients with inflammatory bowel disease: results from the IMmunogenicity to Second Anti-TNF therapy (IMSAT) therapeutic drug monitoring study.

BACKGROUND: Anti-drug antibodies are associated with treatment failure to anti-TNF agents in patients with inflammatory bowel disease (IBD). AIM: To assess whether immunogenicity to a patient's first anti-TNF agent would be associated with immunogenicity to the second, irrespective of drug sequence METHODS: We conducted a UK-wide, multicentre, retrospective cohort study to report rates of immunogenicity and treatment failure of second anti-TNF therapies in 1058 patients with IBD who underwent therapeutic drug monitoring for both infliximab and adalimumab. The primary outcome was immunogenicity to the second anti-TNF agent, defined at any timepoint as an anti-TNF antibody concentration ≥9 AU/ml for infliximab and ≥6 AU/ml for adalimumab. RESULTS: In patients treated with infliximab and then adalimumab, those who developed antibodies to infliximab were more likely to develop antibodies to adalimumab, than patients who did not develop antibodies to infliximab (OR 1.99, 95%CI 1.27-3.20, p = 0.002). Similarly, in patients treated with adalimumab and then infliximab, immunogenicity to adalimumab was associated with subsequent immunogenicity to infliximab (OR 2.63, 95%CI 1.46-4.80, p < 0.001). For each 10-fold increase in anti-infliximab and anti-adalimumab antibody concentration, the odds of subsequently developing antibodies to adalimumab and infliximab increased by 1.73 (95% CI 1.38-2.17, p < 0.001) and 1.99 (95%CI 1.34-2.99, p < 0.001), respectively. Patients who developed immunogenicity with undetectable drug levels to infliximab were more likely to develop immunogenicity with undetectable drug levels to adalimumab (OR 2.37, 95% CI 1.39-4.19, p < 0.001). Commencing an immunomodulator at the time of switching to the second anti-TNF was associated with improved drug persistence in patients with immunogenic, but not pharmacodynamic failure. CONCLUSION: Irrespective of drug sequence, immunogenicity to the first anti-TNF agent was associated with immunogenicity to the second, which was mitigated by the introduction of an immunomodulator in patients with immunogenic, but not pharmacodynamic treatment failure.

SARS-CoV-2 and the Gastrointestinal Tract in Children.

Coronavirus disease 2019 (COVID-19), caused by acute respiratory syndrome coronavirus 2 (SARS-CoV-2), is predominantly a respiratory disease. However, its significant impact on the gastrointestinal (GI) system is now well-known. SARS-CoV-2 enters cells via the angiotensin-converting enzyme-2 (ACE-2) receptor, which is abundantly expressed on lung cells, but also on enterocytes. Several etiopathogenetic mechanisms have been postulated to explain the GI involvement in COVID-19, including loss in intestinal absorption, microscopic mucosal inflammation and impaired ACE-2 function, which plays a significant role in maintaining gut homeostasis. In children the GI manifestations include anorexia, nausea, vomiting, diarrhea and abdominal pain, which may represent the earliest presenting symptoms of the disease. However, although rare, a significant GI mucosal inflammation, such as terminal ileitis mimicking an atypical appendicitis, and other GI manifestations have been reported. COVID-19 pandemic has posed a significant challenge in healthcare provision in term of ability in providing safe diagnostic procedures, face-to-face consultations, and offering comprehensive care. For instance, changes in health services have raised the risk of empirical or sub-optimal management of chronic GI disorders such as inflammatory bowel disease (IBD) due to delayed endoscopic and clinical assessment. This review will discuss the acute GI involvement in COVID-19 in children and reflect on challenges and major changes observed in clinical practice during COVID-19 pandemic by sharing both the published literature and personal experience. We also suggest potential strategies for providing optimal gastroenterology care during this unprecedented era.