Topical Resiquimod Can Induce Disease Regression and Enhance T-cell Effector Functions in Cutaneous T-cell Lymphoma

Early-stage cutaneous T-cell lymphoma (CTCL) is a skin-limited lymphoma with no cure aside from stem cell transplantation. Twelve patients with stage IA-IIA CTCL were treated in a phase 1 trial of 0.03% and 0.06% topical resiquimod gel, a Toll-like receptor 7/8 agonist. Treated lesions significantly improved in 75% of patients and 30% had clearing of all treated lesions. Resiquimod also induced regression of untreated lesions. Ninety-two percent of patients had more than a 50% improvement in body surface area involvement by the modified Severity-Weighted Assessment Tool analysis and 2 patients experienced complete clearing of disease. Four of 5 patients with folliculotropic disease also improved significantly. Adverse effects were minor and largely skin limited. T-cell receptor sequencing and flow cytometry studies of T cells from treated lesions demonstrated decreased clonal malignant T cells in 90% of patients and complete eradication of malignant T cells in 30%. High responses were associated with recruitment and expansion of benign T-cell clones in treated skin, increased skin T-cell effector functions, and a trend toward increased natural killer cell functions. In patients with complete or near eradication of malignant T cells, residual clinical inflammation was associated with cytokine production by benign T cells. Fifty percent of patients had increased activation of circulating dendritic cells, consistent with a systemic response to therapy. In summary, topical resiquimod is safe and effective in early-stage CTCL and the first topical therapy to our knowledge that can induce clearance of untreated lesions and complete remissions in some patients. This trial was registered at www.clinicaltrials.gov as #NCT813320.