For Whom the Bell Tolls? A Toll-Like Receptor 9 Agonist's Journey from Vaccine Adjuvant to Promising Agent in Anti-PD-1-Resistant Melanoma.

Developing effective therapies in anti-PD-1-resistant melanoma is a key unmet need. The combination of pembrolizumab with the intralesional TLR9 agonist vidutolimod showed promise in this patient population with correlative analysis suggesting that patients with a "cold" tumor immune microenvironment may be the best patients to study further. See related article by Ribas et al., p. 2998.