Spatially Resolved Molecular Investigation of Perineural Invasion in Lacrimal Gland Adenoid Cystic Carcinoma

Purpose: The purpose is to characterize the tumor microenvironment and investigate molecular mechanisms underlying perineural invasion (PNI) in lacrimal gland adenoid cystic carcinoma (LGACC) for the discovery of targeted therapies and biomarkers to improve clinical management. Methods: Spatial transcriptomics was performed on histopathologically confirmed LGACC with pronounced PNI. Cellular components were identified using gene signatures, and molecular pathways associated with PNI were analyzed through Gene Ontology analysis of differentially expressed genes between tumor and stromal components. Immunostaining for low-affinity p75NTR ( NGFR ) was conducted on archival LGACC cases with PNI. Results: Spatial transcriptomics yielded an average of 33,885 reads per spot, with 98.6% mapping quality and detection of 17,567 genes. Analyses revealed significant intratumor heterogeneity and identified pathways associated with PNI and treatment resistance, including the upregulation of metallothioneins and heat shock proteins. A distinct p75NTR expression pattern was observed in the spatial cluster involving tumor cells and nerve, which was confirmed by diffuse p75NTR staining in the nerve perineurium in all 10 (100%) LGACC cases with PNI. Conclusions: This study provides novel insights into the complex tumor microenvironment of LGACC PNI, uncovering mechanisms that may drive PNI and treatment resistance. The identification of p75NTR as a potential mediator of neurotropism underscores its relevance as both a therapeutic target and biomarker for PNI in LGACC. Elucidating these molecular factors is critical for developing targeted therapeutics to improve outcomes for patients with this aggressive malignancy.