Single-cell profiling of acral melanoma infiltrating lymphocytes reveals a suppressive tumor microenvironment
Tomoyuki Minowa, Kenji Murata, Yuka Mizue, Aiko Murai, Munehide Nakatsugawa, Kenta Sasaki, Serina Tokita, Terufumi Kubo, Takayuki Kanaseki, Tomohide Tsukahara, Toshiya Handa, Sayuri Sato, Kohei Horimoto, Junji Kato, Tokimasa Hida, Yoshihiko Hirohashi, Hisashi Uhara, Toshihiko Torigoe
Abstract
Acral lentiginous melanoma (ALM) is the most common melanoma subtype in non-Caucasians. Despite advances in cancer immunotherapy, current immune checkpoint inhibitors remain unsatisfactory for ALM. Hence, we conducted comprehensive immune profiling using single-cell phenotyping with reactivity screening of the T cell receptors of tumor-infiltrating T lymphocytes (TILs) in ALM. Compared with cutaneous melanoma, ALM showed a lower frequency of tumor-reactive CD8 clusters and an enrichment of regulatory T cells with direct tumor recognition ability, suggesting a suppressive immune microenvironment in ALM. Tumor-reactive CD8 TILs showed heterogeneous expression of coinhibitory molecules, including KLRC1 (NKG2A), in subpopulations with therapeutic implications. Overall, our study provides a foundation for enhancing the efficacy of immunotherapy in ALM.