192P - Analysis of Tumor-Associated Macrophages and Tumor-infiltrating Lymphocytes within the Tumor Microenvironment of Primary Tumors and Matched Brain Metastases

Background

Response rates of immune checkpoint inhibitors (ICI) differ between primary tumors and brain metastases (BM). Here, we aimed to analyze infiltration patterns of inflammatory cells within the tumor microenvironment (TME) of primary tumors and matched BM tissue samples.

Methods

We retrospectively identified patients who received resection of primary tumor and BM between 01/1990 and 10/2022. Immunohistochemical FFPE tissue staining, density quantification of tumor-associated macrophages (TAMs; CD68⁺, CD163⁺) and tumor-infiltrating lymphocytes (TILs; CD3⁺, CD8⁺, CD45Ro⁺, FoxP3⁺) was performed. Images were processed with QuPath software, heterogeneity of generated heatmaps was measured by Shannon entropy.

Results

74 patients with matched samples were analyzed: 58/74 (78%) non-small cell lung cancer (NSCLC) , 8/74 (11%) breast cancer (BC), 8/74 (11%) renal cell carcinomas (RCC) (61.3% males, 38.7% females; median age 57 years). Median OS after primary diagnosis was 176.4 weeks (range 9.4-829.1). Median time to BM was 58.2 weeks (range -24.9 -520.6). CD163⁺ density was significantly higher in BM, whereas CD8⁺ was significantly lower in BM over all entities (p<.05) compared to primary tumors. CD3⁺ density was lower in BM of NSCLC and BC (p<.001, p=.008, respectively). CD68⁺ showed higher density in BC BM (p=.016) and FoxP3⁺ was higher in NSCLC primary tumors (p<.001; all Wilcoxon rank sum test). Cell density and entropy of FoxP3⁺ correlated in matched samples (p=.002, ρ=.37 and p<.001, ρ=.65), while CD3⁺ (p=.002, ρ=.37) and CD8⁺ (p<.001, ρ=.47) did only in BM. In primary NSCLC, FoxP3⁺ and CD163⁺ showed lower entropy indices, therefore more homogeneous distribution compared to matched BM (p=.002, p=.004, respectively). Multivariable Cox regression model demonstrated significant associations of CD3⁺ density (p=.006) and CD45Ro⁺ entropy (p=.001) in primary tumor with time to BM diagnosis.

Conclusions

Cell densities of CD163⁺-TAMs within the TME of BM are significantly higher compared to primary tumors, whereas CD8⁺ and CD3⁺ TILs are less present in BM. Differences in the inflammatory cell infiltration pattern could explain different ICI responses between primary tumor and BM.

Legal entity responsible for the study

The authors.

Funding

Austrian Federal Ministry for Digital and Economic Affairs, National Foundation for Research, Technology and Development, Christian Doppler Research Association.

Disclosure

M. Preusser: Financial Interests, Personal, Advisory Board: Bayer, Bristol Myers Squibb, Novartis, Gerson Lehrman, CMC Contrast, GSK, Mundipharma, Roche, BMJ Journals, MedMedia, AstraZeneca, AbbVie, Lilly, Medahead, Daiichi Sankyo, Sanofi, Gan & Lee Pharmaceuticals, Merck Sharp & Dohme, Tocagen, Adastra; Financial Interests, Institutional, Research Grant, Clinical Trials and research: Boehringer Ingelheim, Bristol Meyers Squibb, Roche, Daiichi Sankyo, Merck Sharp & Dohme, Novocure, GSK, AbbVie; Non-Financial Interests, Personal, Leadership Role, Brain Tumor Group Chair (current): EORTC; Financial Interests, Institutional, Coordinating PI: PharmaMar; Non-Financial Interests, Personal, Leadership Role, EANO Past-President (current): EANO; Non-Financial Interests, Personal, Other, Member Multi-Site Guideline Advisory Group: ASCO. J.N. Kather: Financial Interests, Personal, Invited Speaker, Talk in 2023: Fresenius, BMS; Financial Interests, Personal, Invited Speaker, Talk in 2022: Eisai, MSD; Financial Interests, Personal, Advisory Board, Scientific Advisory Board since 2022: Owkin, Panakeia, London, UK; Financial Interests, Personal, Advisory Board, Scientific Advisory Board since 2023: DoMore Diagnostics; Financial Interests, Personal, Invited Speaker, Talk in June 2023: Bayer; Financial Interests, Personal, Invited Speaker, Talk in Sept 2023: Roche Diagnostics International Ltd; Financial Interests, Personal, Advisory Board, consultation: Repare Therapeutics USA; Financial Interests, Personal, Invited Speaker, Talk in Oct 2023: Pfizer; Financial Interests, Personal, Stocks/Shares, Shares and part-time activities in a company that provides artificial intelligence services.: StratifAI GmbH. A.S. Berghoff: Other, Personal, Other: Daiichi Sankyo, Roche, Bristol Meyers Squibb, Merck, Daiichi Sankyo, Amgen, AbbVie. All other authors have declared no conflicts of interest.