Response to: ‘Dupilumab as a potential steroid-sparing treatment for IgG4-related disease’ by Della-Torre et al

TLDR: It is proposed that dupilumab, a monoclonal anti-interleukin 4 (IL-4) and IL-13 antibody, would be able to treat the patient’s condition mechanistically through two pathways, and that IgG4-RD is an example of type 2 inflammation, similar to other conditions that have been misclassified as non-type 2 inflammation in the past.

Abstract: We thank Della-Torre et al for their interest in our paper and for providing their thoughts through correspondence.1 2 As they have summarised, our case described a patient whom was prescribed a 40 mg daily dose of prednisone to treat his IgG4-related disease (IgG4-RD); however, the patient declined to pursue additional adjunct immunosuppressants due to the concern of adverse effects.1 To hopefully mitigate such concerns and control his disease, we proposed that dupilumab, a monoclonal anti-interleukin 4 (IL-4) and IL-13 antibody, would be able to treat the patient’s condition mechanistically through two pathways. First, because IL-4 is the signal which plays a pivotal role in class switching from IgM to IgG, we theorised that dupilumab would be able to reduce the amount of serum IgG and IgG4, which is a hallmark of IgG4-RD pathology. Second, because dupilumab inhibits IL-13, which is implicated in the activation of fibroblasts causing fibrosis,3 we believed dupilumab would also be able to address this component of the IgG4-RD mechanism of disease. Upon initiation of dupilumab treatment, we observed remission of the patient’s condition with improvements starting as soon as 3 months post-dupilumab treatment.1 As such, our theory is that IgG4-RD is an example of type 2 inflammation, similar to other conditions such as chronic spontaneous urticaria (CSU) that have been misclassified as non-type 2 inflammation in the past.4 This is what we believe allows dupilumab to be an …