Abstract 6649: Prevalence and spatial interplay of mononuclear phagocyte and lymphocyte subpopulations in 49 carcinoma entities in respect to its TIM3, PD-1, PD-L1 and CTLA-4 expression using BLEACH&STAIN
Authors: Huang Zhihao , Debatin Nicolaus F. , Bady Elena , Mueller Jan H. , Mandelkow Tim , Lurati Magalie C. , Simon Ronald , Dum David , Sauter Guido , Büscheck Franziska , Hoeflmayer Doris , Weidemann Sören , Hube-Magg Claudia , Clauditz Till , Lennartz Maximilian , Burandt Eike , Blessin Niclas C. 
Published: April 2023

Abstract
Background: A combination of different immune-checkpoint-inhibitors (ICIs) have shown remarkable success in several tumor entities. However, the likelihood of positive response to ICIs is poor in most tumor entities and recent evidence suggests that the quantity and the expression level of immune checkpoints such as TIM3, CTLA-4, PD-1 of tumor infiltrating lymphocytes (TILs) influences the likelihood of response to immune checkpoint inhibitors.
Design: To assess the density and spatial interplay of 42 immune checkpoint expressing leukocyte subpopulations in 6031 tumor samples from 49 carcinoma (sub)entities two different types of tissue microarrays (0.6 mm and 4 mm in diameter) were stained with 21 antibodies using our BLEACH&STAIN multiplex fluorescence immunohistochemistry approach. A deep learning-based framework comprising two different convolutional neuronal networks (U-Net and DeepLabv3+) was used for image analysis.
Results: We found that the mean overall fraction of TIM3, PD-1, PD-L1 and CTLA-4 expression on M1, M2 macrophages, cD11c+ dendritic cells, CD8+ cytotoxic T-cells, CD4+ T-helper cells, FOXP3+ Tregs and CD20+ B-cells, ranged from 10% (sum of the fractions of immune checkpoint expression) in small cell carcinomas of the prostate up to 123 % in squamous cell carcinoma of the lung. Tumor types approved for checkpoint inhibitor therapy, including adenocarcinomas of the lung (121 %), small cell carcinoma of the lung (74%), malignant melanoma (59 %), and clear cell renal cell cancer (49%) were all ranking among the upper half of our list of mean fractions of overall immune checkpoint expression. Spatial analysis and the shift in immune cell compositions revealed that in most carcinoma (sub)entities, the overall immune cell density and fraction of immune checkpoint expression of individual patients occasionally exceeded the average immune cell density and fraction of tumors for which checkpoint inhibitors have been approved.
Conclusion: These data support the concept that among most carcinoma entities at least some individual patients may benefit from treatment with immune checkpoint inhibitors.
Citation Format: Zhihao Huang, Nicolaus F. Debatin, Elena Bady, Jan H. Mueller, Tim Mandelkow, Magalie C. Lurati, Ronald Simon, David Dum, Guido Sauter, Franziska Büscheck, Doris Hoeflmayer, Sören Weidemann, Claudia Hube-Magg, Till Clauditz, Maximilian Lennartz, Eike Burandt, Niclas C. Blessin. Prevalence and spatial interplay of mononuclear phagocyte and lymphocyte subpopulations in 49 carcinoma entities in respect to its TIM3, PD-1, PD-L1 and CTLA-4 expression using BLEACH&STAIN [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 6649.