Dupilumab-associated mycosis fungoides: a cross-sectional study.

Treating atopic dermatitis (AD) with dupilumab, a monoclonal antibody that inhibits interleukin-4 (IL-4) and interleukin-13 (IL-13), may be associated with the progression of mycosis fungoides (MF).This study aims to examine the associations between the length of dupilumab treatment, age and sex, and the onset of MF.An institutional data registry and literature search were used for a retrospective cross-sectional study. Only patients with a diagnosis of MF on dupilumab for the treatment of AD and eczematous dermatitis were included.The primary outcome was the length of dupilumab exposure, age, sex, and the onset of MF. Linear correlations (Pearson) and Cox regression analysis were used to assess the correlation and the risk.A total of 25 patients were included in this study. Five eligible patients were identified at our institution. In addition, a PubMed review identified an additional 20 patients. At the time of MF diagnosis, the median age was 58, with 42% female. Disease history was significant for adult-onset AD in most patients (n = 17, 65.4%) or recent flare of AD previously in remission (n = 3, 11.5%). All patients were diagnosed with MF, and one patient progressed to Sézary syndrome while on dupilumab, with an average duration of 13.5 months of therapy prior to diagnosis. Tumor stage at diagnosis of MF was described in 19 of the cases and ranged from an early-stage disease (IA) to advanced disease (IV). Treatment strategies included narrow-band UVB therapy, topical corticosteroids, brentuximab, pralatrexate, and acitretin. Male gender, advanced-stage disease, and older age correlated significantly with the hazard of MF onset and a shorter time to onset during dupilumab treatment.Our results suggest a correlation between the duration of dupilumab treatment and the diagnosis of MF, the higher MF stage at diagnosis, and the shorter the duration of using dupilumab to MF onset. Furthermore, elderly male patients appeared to be more at risk as both male gender and older age correlated with a hazard of MF diagnosis. The results raise the question as to whether the patients had MF misdiagnosed as AD that was unmasked by dupilumab or if MF truly is an adverse effect of treatment with dupilumab. Close monitoring of these patients and further investigation of the relationship between dupilumab and MF can shed more light on this question .