Tumor Microenvironment Cellular Crosstalk Predicts Response to Adoptive TIL Therapy in Melanoma

Adoptive cell therapy (ACT) using ex vivo expanded tumor-infiltrating T lymphocytes (TILs) can mediate responses in metastatic melanoma, but long-term efficacy remains limited to a fraction of patients. Here we interrogated tumor-microenvironment (TME) cellular states and interactions of longitudinal samples from 13 metastatic melanoma patients treated with TIL-ACT in our clinical study ([NCT03475134][1]). We performed single-cell RNA-seq and spatial proteomic analyses in pre- and post-ACT tumor tissues and showed that responders exhibited higher tumor cell-intrinsic immunogenicity. Also, endogenous CD8+ TILs and myeloid cells of responders were characterized by increased cytotoxicity, exhaustion and costimulation and type-I IFN signaling, respectively. Cell-cell interaction prediction analyses corroborated by spatial neighborhood analyses revealed that responders have rich baseline intratumoral and stromal tumor-reactive T-cell networks with activated myeloid populations. Successful TIL-ACT therapy further reprogrammed the myeloid compartment and increased TIL-myeloid networks. Our systematic target discovery study reveals CD8+ T-cell network-based biomarkers that could improve patient selection and guide the design of ACT clinical trials. ### Competing Interest Statement SZ is currently an employee of F. Hoffmann-La Roche. RD has intermittent, project focused consulting and/or advisory relationships with Novartis, Merck Sharp & Dhome (MSD), Bristol-Myers Squibb (BMS), Roche, Amgen, Takeda, Pierre Fabre, Sun Pharma, Sanofi, Catalym, Second Genome, Regeneron, Alligator, T3 Pharma, MaxiVAX SA, Pfizer and touchIME outside the submitted work. OM has consulting/advisory roles for Bristol Myers Squibb, MSD, Roche, Novartis, Amgen, Pierre Fabre, Neracare, research grants from Bristol Myers Squibb, MSD, Amgen. PC, consultant advisor or paid speaker for Bristol Myers Squibb, MSD, Novartis, Pierre Fabre, Amgen, Nektar, has received research funding from Bristol Myers Squibb, Pierre Fabre. GC has received grants from Celgene, Boehringer-Ingelheim, Roche, Bristol Myers Squibb, Iovance Therapeutics and Kite Pharma. The institution GC is affiliated with has received fees for GC participation on advisory boards or for presentation at a company-sponsored symposium from Genentech, Roche, Bristol Myers Squibb, AstraZeneca, NextCure, Geneos Tx and Sanofi/Avensis. GC holds patents around antibodies and receives royalties from the University of Pennsylvania regarding technology licensed to Novartis. DDL, AH, and GC are inventors on patent applications filed by the Ludwig Institute for Cancer Research Ltd pertaining to the subject matter disclosed herein and such patent applications have been licensed to Tigen Pharma SA. All the other authors have no conflict of interest to declare. [1]: /lookup/external-ref?link_type=CLINTRIALGOV&access_num=NCT03475134&atom=%2Fbiorxiv%2Fearly%2F2022%2F12%2F23%2F2022.12.23.519261.atom