Investigating Nerve Innervation and Perineural Invasion in Solid Tumors

The role of nerve innervation in cancer progression remains highly debated. While various in vitro and in vivo models suggest that tumor cells can actively induce neoneurogenesis, tissue-based evidence remains sparse. In this project, we critically examine the hypothesis of tumor-associated nerve innervation by seeking direct, tissue-based evidence of nerve innervation and sprouting in relation to histopathological tumor features.Our study cohort comprises diagnostic FFPE whole-tissue samples from six solid tumor types: breast cancer (Luminal A/B, HER2+, TNBC), non-small cell lung cancer (adenocarcinoma, squamous cell carcinoma), colorectal cancer, pancreatic cancer (PDAC and periampullary adenocarcinoma), prostate cancer, and urinary bladder cancer.Nerve structures are identified via multiplexed immunofluorescence and multispectral imaging, targeting neurofilament light chain (NFL, 70 kDa) and growth-associated protein 43 (GAP43). To delineate the tumor microenvironment, additional markers include CD34 (perineural sheath), CD31 (endothelial cells), CD3 (T-cells), and pan-cytokeratin (tumor cells). We developed both a deep-learning-based algorithm and a thresholding approach to segment nerve fibers and characterize their spatial organization. A custom Python script quantifies nerve density (nerves/tumor area), nerve size (μm2), and the integrity of the perineural sheath via CD34 staining. In parallel, we are constructing 3D nerve reconstructions by aligning and analyzing 30 consecutive 4 μm sections using tailored Python tools.Perineural invasion, as defined as direct contact between tumor cells and nerves, is most frequently observed in tumors from highly innervated organs such as PDAC and prostate cancer, while appearing only sporadically in the other tumor types.In subsequent analyses, nerve features will be systematically correlated with histopathological tumor characteristics, microenvironmental profiles, and clinical data. Ultimately, this study aims to generate a comprehensive atlas of nerve-tumor interactions in human cancer and to delineate both shared and tumor-type-specific patterns of innervation and perineural invasion. Citation Format: Hui Yu, Aglaia Schiza, Victor Ponten, Viktoria Thurfjell, Amanda Lindberg, Julia Sidenius Johansen, Ulrike Segersten, Anca Dragomir, Bengt Glimelius, Artur Mezheyeuski, Astrid Børretzen, Yun-Fan Sun, Lars A. Akslen, Patrick Micke, Carina Strell. Nerve innervation in solid tumors [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2026; Part 1 (Regular Abstracts); 2026 Apr 17-22; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2026;86(7 Suppl):Abstract nr 720.