Immune suppression in the tumor-draining lymph node corresponds with distant disease recurrence in patients with melanoma

Immune checkpoint blockade (ICB) using anti-PD-1/PD-L1 and anti-CTLA-4 antibodies significantly enhances survival in metastatic melanoma patients and has recently been shown to prolong relapse-free survival in stage III and high-risk stage II melanoma patients (Eggermont et al., 2018; Luke et al., 2022; Robert et al., 2015). However, a significant proportion of patients does not respond to ICB prior to or following surgery, for reasons incompletely understood. We and others recently identified tumor-draining lymph nodes (TDLNs) to be critically involved in anti-PD-L1 treatment efficacy in preclinical tumor models (Dammeijer et al., 2020; Fransen et al., 2018).