Sex-based considerations in the choice for a TLR9 or TLR7/8 agonist to arm the sentinel lymph node in early-stage melanoma

Intradermal delivery of the Toll-like receptor (TLR)-9 agonist agatolimod/CPG7909, prior to sentinel lymph node (SLN) biopsy was previously shown to induce locoregional and systemic immunity, reduce tumor-involved SLN rates, and improve recurrence-free survival in patients with early-stage melanoma. Remarkably, men exhibited superior dendritic cell (DC) maturation. Here, we report on further sex-based differences in the immune response after intradermal administration of CPG7909, which included higher CD80/CD83 expression levels in conventional (c) DC subsets in men's as compared to women's SLN, as well as higher ex-vivo release levels of IL-1 beta, TNF, and IL-6 (all contributors to cDC activation) and Th1/Th2 cytokines. In an effort to identify a more effective DC-activating therapy for women, we compared the in-vitro effects of CPG7909 with those of the TLR7/8 agonist resiquimod/R848 on SLN single cells from female patients. R848 induced superior cDC subset activation and TNF, IL-6, IL-10, IL-12, IFN gamma, and CXCL10 release. Correlation analyses suggested that IFN alpha, TNF, and IL-6 were key for CPG7909-induced LNR-cDC activation, whereas R848's effect appeared more cytokine-independent. We conclude that combining locally delivered CPG7909 and R848 in early-stage melanoma will ensure full-range DC subset activation and robust pro-inflammatory T-cell responses in melanoma SLN, independent of sex.