Presentation (CTI)

OBJECTIVES: Successful utilization of HER2-targeted therapies remains a challenge, particularly outside of academic hospitals (i.e. community setting). Large language models (LLM’s) are positioned to help rationalize prescribing behaviors and connect biomarker status with treatment decisions. We aim to investigate HER2 testing rates, prevalence, and prescribing habits across solid tumor types in a predominantly (>80%) community setting.
METHODS: 10-years of HER2 testing data and HER2 profiles of 18,844 Neogenomics patients from 12/2023 -12/2025 were analyzed/integrated with clinical data aggregated from national HIE and processed via the xCures platform (8/2025 - 12/2025). Structured data from electronic medical records were supplemented with LLM’s and trained to perform natural language processing/extraction, which standardized information from pathology reports, progress notes, prescription, and imaging records.
RESULTS: HER2 testing data showed a 4.5-fold increase in testing, with 2023-2025 growing >17% year-over-year. The most frequently tested malignancies were breast, lung, colorectal, gastric, and endometrial carcinomas (89% of HER2 testing). Esophageal (21.3%), bladder (17.1%), brain (16.1%), gastric (14.1%), endometrial (13.1%), liver (12%), and breast (12%) had the highest prevalence of HER2 positivity (IHC 3+ or FISH+) while prostate (1%), pancreas (4.1%), lung (4.3%), kidney (4.7%), vulva (4.7%), and colorectal (4.8%) had the lowest. In patients with available treatment information 90 days within testing date, 38.3% (220/573) of HER2 positive patients received HER2-targeted therapy. The most administered therapy was pertuzumab+trastuzumab (52%) followed by trastuzumab (25%), trastuzumab deruxtecan (6.3%); pertuzumab (5.4%), trastuzumab emtansine (3.1%), pertuzumab+trastuzumab+trastuzumab emtansine (1.8%), other combination therapies (1.8%) and ERBB2 TKI’s (1.3%).
CONCLUSIONS: Although HER2 is expressed in multiple solid tumors and testing has increased dramatically, HER2-targeted therapies are only prescribed in 38% of patients and newer generation HER2-targeted therapies are not frequently utilized. Future research will focus on how HER2 scoring (breast vs. gastric), HER2 testing methodologies (i.e. - IHC vs. molecular), and biomarkers (i.e. CGP) may influence treatment decisions.