Abstract A082: Single-cell RNA-sequencing of metastatic melanoma identifies a cancer cell-intrinsic program associated with immune checkpoint inhibitor resistance

Immune checkpoint inhibitors (ICI) produce durable responses in some melanoma patients, but many patients derive no clinical benefit. The molecular underpinnings of ICI resistance involve intricate cell-cell interactions that are yet elusive. To systematically map the interactions between malignant and immune cells in the tumor ecosystem, we applied single-cell RNA sequencing to 31 human melanoma tumors, profiling thousands of malignant, immune, and stromal cells. We identified a transcriptional program in malignanT-cells that is strongly associated with T-cell exclusion and immunotherapy resistance. Using highly multiplexed in situ imaging we first demonstrated that this program characterizes malignanT-cells in “cold” niches. Next, we showed that the program predicts clinical responses to ICI according to multiple independent validation cohorts, including a new cohort that we obtained from 112 melanoma patients treated with anti-PD-1 therapy. We then identified CDK4/6 as master regulators of this resistance program, and found that CDK4/6 inhibitors repress the program and shift melanoma cells into a senescence-associated secretory phenotype. Lastly, we showed that CDK4/6-inhibition leads to a substantial reduction in melanoma tumor outgrowth in a B16 mouse model when given in combination with immunotherapy. Taken together, our study provides a high-resolution landscape of ICI-resistant cell states, identifies clinically predictive signatures, and forms a basis for the development of novel therapeutic strategies that could overcome immunotherapy resistance. Citation Format: Livnat Jerby, Parin Shah, Michael S. Cuoco, Christopher Rodman, Mei-Ju Su, Johannes M. Melms, Rachel Leeson, Abhay Kanodia, Shaolin Mei, Jia-Ren Lin, Shu Wang, Bokang Rabasha, David Liu, Gao Zhang, Claire Margolais, Orr Ashenberg, Patrick A. Ott, Elizabeth I. Buchbinder, Riz Haq, Stephen Hodi, Genevieve M. Boland, Ryan J. Sullivan, Dennie Frederick, Benchun Miao, Tabea Moll, Keith Flaherty, Meenhard Herlyn, Russell S. Jenkins, Rohit Thummalapalli, Monika S. Kowalczyk, Israel Canadas, Bastian Schilling, Adam N.R Cartwright, Adrienne M. Luoma, Shruti Malu, Patrick Hwu, Chantale Bernatchez, Marie-Andree Forget, David A. Barbie, Alex K. Shalek, Itay Tirosh, Peter K. Sorger, Kai W. Wucherpfennig, Eliezer M. Van Allen, Dirk Schadendorf, Bruce E. Johnson, Asaf Rotem, Orit Rosenblatt-Rozen, Levi A. Garraway, Charles H. Yoon, Benjamin Izar, Aviv Regev. Single-cell RNA-sequencing of metastatic melanoma identifies a cancer cell-intrinsic program associated with immune checkpoint inhibitor resistance [abstract]. In: Proceedings of the Fourth CRI-CIMT-EATI-AACR International Cancer Immunotherapy Conference: Translating Science into Survival; Sept 30-Oct 3, 2018; New York, NY. Philadelphia (PA): AACR; Cancer Immunol Res 2019;7(2 Suppl):Abstract nr A082.