Unexpected findings may drive future drug choices
“Development of antidrug antibodies in patients on biologics for inflammatory bowel disease is an important mechanism for loss of response to a therapeutic agent,” Kim L. Isaacs, MD, AGAF, of the University of North Carolina at Chapel Hill, said in an interview. “To date the causes of development of ADAs is relatively understudied. Our approach to prevent ADA includes increasing immunosuppression in patients most commonly with combination therapy with thiopurines. If factors that provoke or prevent antibody formation are elucidated, therapy can be tailored to prevent ADAs and maximize the duration of response of many of our biologic therapies.”
Dr. Kim L. Isaacs
A prior study performed by the ABIRISK European consortium demonstrated associations with antibiotics. “In this study, there was a differential effect of cephalosporins/penicillins (increased immunogenicity) and macrolides (decreased immunogenicity),” she said. “These studies suggest that the microbiome may be important in ADA formation to biologics – this is a concept that is novel and unexpected.
“The rationale for the choice of antibiotics in the population studied is not known, and it is possible that different infections may have led to different antibiotic choices, which in turn may have affected immunogenicity,” said Dr. Isaacs. However, clinicians might be able to tailor antibiotic choice in the future if the microbiome is playing a major role in risk for development of ADA.
“Further research is needed to further correlate microbiome changes with immunogenicity, to look at other classes of antibiotics and their role in immunogenicity, and to clarify the infections or reasons that these patients are receiving antibiotics,” Dr. Isaacs concluded.
Understanding the microbiome
Recent observations have shown associations between clinical response to anti-TNF and gut microbiota composition, noted Jatin Roper, MD, of Duke University, Durham, N.C. “More broadly, a growing body of evidence suggests that the gut microbiota modulates the metabolism of many therapeutic agents, as well as immune responses to infections.”
That said, Dr. Roper was surprised that “clinical use of different antibiotics, often short term, had such distinct effects on ADA levels.” Furthermore, “these findings suggest that distinct microbiota or microbial metabolic products impact antibody development to common immunomodulatory therapies in opposite ways,” which is itself a surprising finding.
Such antibodies to anti-TNF therapy are common in IBD, he said, but one implication of the study is how antibiotics could be carefully used "to reduce risk of ADAs and enhance efficacy of anti-TNF therapy."
However, because any antibiotic therapy will modify the gut microbiome and lead to unwanted effects, “further research is needed on how these agents impact the gut microbiome, with the ultimate goal of identifying specific microbiota or microbial metabolic products that can reproduce the intriguing findings of this paper.”
The study was supported in part by the Leona M. and Harry B. Helmsley Charitable Trust and the Israeli Ministry of Science and Technology. Dr. Gorelik had no financial conflicts to disclose. Several coauthors disclosed relationships with multiple pharmaceutical companies including AbbVie, CytoReason, Takeda, and Pfizer. Dr. Isaacs had no financial conflicts to disclose, but serves on the GI&Hepatology News board of editors. Dr. Roper had no relevant disclosures.