New Combination Therapy Using an Antibody (Mogamulizumab) and Radiation Therapy for Cutaneous T-Cell Lymphoma

Cutaneous T-cell lymphoma (CTCL), often referred to as skin lymphoma, is a rare type of non-Hodgkin lymphoma. In its early stages, it is often limited to skin changes such as redness, scaling, or itching, but as it progresses, it can also affect lymph nodes or internal organs. CTCL is a malignant proliferation of T-lymphocytes that manifests specifically on the skin. Depending on the stage and severity, there are subtypes; the best-known are mycosis fungoides (MF) and Sézary syndrome (SS).

Treatment depends on the type, aggressiveness, and extent of the lymphoma. Treatment approaches include those that specifically target the skin (e.g., light therapy, topical steroids, localized radiation therapy) and systemic approaches (e.g., chemotherapy or targeted drugs). Mogamulizumab is an antibody that targets CCR4, a protein found on the surface of many CTCL cells, leading to their destruction. Mogamulizumab is approved for the treatment of previously treated MF and SS. An established treatment for extensive skin involvement is total skin electron beam therapy (TSEB), a form of radiation therapy in which the entire skin surface is irradiated.

The goal of the MOGAT study is now to investigate the efficacy and safety of the combination of mogamulizumab and TSEB for the first time. Both treatments are approved individually, but not as a standard combination. All patients participating in the study will receive the experimental combination treatment (single-arm study). First, they will receive 2 cycles of mogamulizumab alone (induction therapy), followed by TSEB (typically spread over several weeks). Afterward, patients will again receive mogamulizumab as maintenance therapy until the disease progresses or other reasons require discontinuation. Follow-up will continue for up to 5 years after the last patient is enrolled. The primary endpoint is the rate of complete response of the skin lesions.

Women and men aged 18 years and older with cutaneous T-cell lymphoma (mycosis fungoides or Sézary syndrome) in stages 1B–2B who have experienced disease progression after at least one prior systemic treatment are eligible to participate in the study. Patients must not have previously been treated with TSEB, mogamulizumab, or any other CCR4 inhibitor.