Unleashed monocytic engagement in Sézary syndrome during the combination of anti-CCR4 antibody with type I interferon.

ABSTRACT: Sézary syndrome (SS) is an aggressive leukemic expansion of skin-derived malignant CD4+ T cells. Drug monotherapy often results in disease relapse because of the heterogenous nature of malignant CD4+ T cells, but how therapies can be optimally combined remains unclear because of limitations in understanding the disease pathogenesis. We identified immunologic transitions that interlink mycosis fungoides with SS using single-cell transcriptome analysis in parallel with high-throughput T-cell receptor sequencing. Nascent peripheral CD4+ T cells acquired a distinct profile of transcription factors and trafficking receptors that gave rise to antigenically mature Sézary cells. The emergence of malignant CD4+ T cells coincided with the accumulation of dysfunctional monocytes with impaired fragment crystallizable γ-dependent phagocytosis, decreased responsiveness to cytokine stimulation, and limited repertoire of intercellular interactions with Sézary cells. Type I interferon supplementation when combined with a monoclonal antibody targeting the chemokine receptor type 4 (CCR4), unleashed monocyte induced phagocytosis and eradication of Sézary cells in vitro. In turn, coadministration of interferon-α with the US Food and Drug Administration-approved anti-CCR4 antibody, mogamulizumab, in patients with SS induced marked depletion of peripheral malignant CD4+ T cells. Importantly, residual CD4+ T cells after Sézary cell ablation lacked any immunologic shifts. These findings collectively unveil an auxiliary role for augmenting monocytic activity during mogamulizumab therapy in the treatment of SS and underscore the importance of targeted combination therapy in this disease.

Dual-Positive CD4/CD8 Primary Cutaneous Peripheral T-Cell Lymphoma Previously Classified as Mycosis Fungoides a Tumor D'Emblée.

Cutaneous peripheral T-cell lymphoma, not otherwise specified represents a "waste basket" of all cases that cannot be put into another of the categories of mature cutaneous T-cell lymphoma. Previously, the sudden multifocal development of cutaneous CD4 tumors without preceding a patch or plaque stage was classified as d'emblée form of mycosis fungoides (MF). Currently, the term "MF" reserved only for the classic Alibert-Bazin type characterized by the evolution of patches, plaques, and tumors or for variants showing a similar clinical course. The authors describe a 75-year-old white woman who presented with a solitary skin tumor in the right supraclavicular region, with no lymph node or systemic involvement. Local external beam radiation treatment resulted in a complete response. The patient relapsed after 5 months with new tumors in the left neck and left upper chest. Biopsy of the lesions showed a dermal infiltrate of atypical small- to medium-sized T-lymphocytes, and immunohistochemical staining showed coexpression of CD4/CD8 in a subset of these cells, which was confirmed with flow cytometry of the tumor. Although the patient had no preceding patch or plaque stage, the authors herein report this extremely rare case of CD4/CD8 dual-positive peripheral T-cell lymphoma, not otherwise specified presented as MF d'emblée and discuss the seldom similar cases published previously.