Abstract 3977: Neoadjuvant chemotherapy and radiation shape the local and regional adaptive antitumor immune response in lung squamous cell carcinomas
Authors: Krupar Rosemarie , Nieder Justin , Braegelmann Johannes , Haarmann Mareike , Goldmann Torsten , Ruane Sharon , Milbich Timo , Boehm Cornelius , Ruff Lukas , Ribbat-Idel Julika , Watermann Christian , Perner Sven , Kuempers Christiane 
Published: March 2024

Abstract
Chemotherapy (CT) and radiotherapy (RT) are known for their stimulating as well as inhibiting effects on the anti-tumor immune response. This study aimed to understand how CT and RT change the local immune microenvironment of the tumor and the regional immune response in draining lymph nodes. Evaluations were performed on lung squamous cell carcinomas (LUSC) with a special focus on tertiary lymphoid structures (TLS) and lymph follicles.
A cohort of 21 untreated LUSC (naiveLUSC) and 21 matched neoadjuvantly treated LUSC (neoLUSC) was compiled. Digitized H&E whole slide images of the tumor and of two representative probes of a proximal and distal lymph node were assessed. A pathologist blinded to the groups assigned tumors to one of three immunophenotypes (inflamed, excluded, desert) by visual analysis. Tertiary lymphoid structures (TLS) in the tumor area and lymph follicles in the regional lymph nodes were counted and characterized according to their maturation status (with/without germinal center). RNAseq analyses were performed for a subset of tumors.
NeoLUSC tended to more frequently have a desert immune phenotype (6/21 versus 1/21, p=0.0931). The mean number of TLS was significantly reduced in neoLUSC compared to naiveLUSC (4 versus 9, p=0.0179). Additionally, neoLUSC had a significantly lower likelihood for the presence of mature TLS with germinal centers (3/21 versus 9/21, p=0.0327). While the mean number of lymph follicles in regional lymph nodes was comparable between neoLUSC and naiveLUSC, neoLUSC had a significantly reduced number of mature lymph follicles (20% versus 41% of lymph follicles, p=0.0376) in distant lymph nodes and showed a similar, but less pronounced trend in proximal lymph nodes. In general, the amount of TLS correlated with the amount of lymph follicles in naiveLUSC patients (p=0.0154), but not in neoLUSC patients. Across the complete cohort, long-term survivors (&gt;2 years) tended to have higher numbers of lymph follicles in lymph nodes than short term survivors (1.6 versus 1.1 lymph follicles/mm2, p=0.0805). RNAseq analysis revealed a significant upregulation of inflammatory gene sets and downregulation of cell cycle associated gene sets in neoLUSC as compared to naiveLUSC.
This study demonstrates that CT and RT are potent, but multimodal influencers of the local tumor immune microenvironment as well as the regional immune response of the draining lymph nodes. While gene expression results underline the inflammation promoting effect of CT and RT, histological evaluations suggest that CT and RT negatively affect the adaptive anti-tumor immune response by reducing the development and maturation of TLS and lymph follicles in the lymph nodes. Next steps include an artificial intelligence based cell characterization and spatial evaluation of the tumor immune microenvironment to further unveil functional changes induced by CT and RT.
Citation Format: Rosemarie Krupar, Justin Nieder, Johannes Braegelmann, Mareike Haarmann, Torsten Goldmann, Sharon Ruane, Timo Milbich, Cornelius Boehm, Lukas Ruff, Julika Ribbat-Idel, Christian Watermann, Sven Perner, Christiane Kuempers. Neoadjuvant chemotherapy and radiation shape the local and regional adaptive antitumor immune response in lung squamous cell carcinomas [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 3977.