Low-Dose Intralesional Recombinant Interferon-α2b in the Treatment of Mycosis Fungoides

Mycosis fungoides (MF), the most common form of cutaneous T-cell lymphoma (CTCL), is characterized by malignant CD4+ skin-homing T-cells that drive formation of cutaneous patches, plaques, and/or tumors. MF's known immunogenicity makes it an ideal candidate for local immunotherapy. Recombinant human leukocyte interferon-α2 (rIFN-α2) has well-established immunomodulatory, antiproliferative, and antitumor effects; and relatively low levels of endogenous IFN-α have been observed within MF lesions. As a systemic therapy delivered via subcutaneous (SC) or intramuscular (IM) injection, rIFN-α2 has previously shown efficacy against MF. Due to high levels of toxicity associated with the systemic dosing required for improvement of disease, rIFN-α2 has had limited use in the treatment of MF. For these reasons, we sought to deliver rIFN-2 as a local immunotherapy, and herein describe two cases of MF successfully managed with intralesional injections of low-dose rIFN-α2. With limited reporting in the medical literature, intralesional injection of rIFN-α2 has shown efficacy, but with high frequency of associated systemic side effects. Towards a better tolerated, localized immunotherapy, we initiated treatment in two MF patients with low dose (0.5 MU) rIFN-α2 per injection that led to marked responses, and subsequent dosing to 1.0 MU ultimately led to complete resolution of the treated lesions without the generalized side effects observed with systemic administration of rIFN-α2. These cases suggest that low-dose intralesional rIFN-α2 may be an efficacious and well-tolerated local immunotherapy for early stage MF, providing a therapeutic option for the management of chronic, recalcitrant lesions.