Mogamulizumab-induced photosensitivity in patients with mycosis fungoides and other T-cell neoplasms.

BACKGROUND

Mogamulizumab (Mog) is a defucosylated, therapeutic monoclonal antibody, targeting CCR4 and was first approved in Japan for the treatment of adult T-cell leukaemia/lymphoma (ATLL), followed by cutaneous T-cell lymphoma and peripheral T-cell lymphoma.

OBJECTIVE

To retrospectively investigate development of photosensitivity in patients with mycosis fungoides and other T-cell neoplasms after treatment with Mog.

METHODS

We treated seven cutaneous lymphoma patients with Mog. Upon combination treatment with narrow-band UVB, we noticed that four patients developed photosensitivity dermatitis following Mog therapy, including two cases of mycosis fungoides, one case of adult T-cell leukaemia/lymphoma and one case of EB virus-associated T-cell lymphoproliferative disorder. Phototest was performed with UVA and UVB, and immunohistochemical staining for CD4, CD8 and Foxp3 was conducted in both photosensitivity and lymphoma lesions.

RESULTS

Phototest revealed that the action spectrum of the photosensitivity was UVB in three cases and both UVB and UVA in one case. Histopathologically, the photosensitive lesions were characterized by a lichenoid tissue reaction with a CD8 T cell-dominant infiltrate, sharing the feature with chronic actinic dermatitis, an autoreactive photodermatosis with a cytotoxic T-cell response. Foxp3 regulatory T cells (Tregs) were decreased in the photosensitivity lesions compared with the lymphoma lesions.

CONCLUSION

Increased incidence of photosensitivity reaction was observed during Mog treatment. Decreased number of Tregs in the lesional skin suggests that this reaction is possibly induced by autoreactive cytotoxic T cells.