Abstract 6298: The value of routine trastuzumab-related cardiac toxicity monitoring in gastrointestinal cancers

Abstract Background: It is a common practice to monitor trastuzumab-related cardiac toxicity (TRCT) using left ventricular ejection fraction (LVEF) in patients who receive trastuzumab-containing therapy for human epidermal growth factor receptor 2 (HER2) -positive cancers. However, this monitoring approach does not appear cost effective in patients with HER2-positive gastrointestinal (GI) cancers given poor overall survival (OS). Here, we aim to examine the incidence of clinically significant TRCT in this target population. Methods: This is a retrospective cohort study of patients with advanced HER2-positive GI cancers who received trastuzumab-containing therapies (trastuzumab +/- pertuzumab, chemotherapy +/- immunotherapy + trastuzumab, trastuzumab deruxtecan) between 2011 and 2023. HER2 status was determined by immunohistochemistry, fluorescent in situ hybridization, and/or next generation sequencing. LVEF was estimated by serial transthoracic echocardiograms (TTE). Continuous variables were summarized as median and interquartile range (IQR). Paired Wilcoxon signed rank test was used to compare serial LVEF. OS was estimated using Kaplan-Meier method. Results: A total of 243 patients were included in this study with a median age of 64 (IQR: 55-70) years. 139 (57%) patients had esophageal or GEJ adenocarcinoma; 45 (19%) patients had gastric cancer; 37 (15%) patients had colorectal cancer; and the rest had other GI cancers. Median follow-up time was 18. 6 (IQR: 9. 2-36) months. Median OS from cancer diagnosis and the first dose of trastuzumab-containing therapy were 24. 1 (95%CI: 20. 2-30. 2) and 11. 7 (95%CI: 10. 4-15. 6) months, respectively. Patients received a median of 13 cycles of trastuzumab-containing therapy for a median duration of 4. 1 (IQR: 1. 4-10. 1) months. The median number of TTE each patient had throughout therapy was 2 (IQR: 1-4). Median baseline LVEF was 61% (IQR: 56-65%) which was significantly higher (p0. 001) than the median lowest LVEF of 58% (IQR: 53-62%) during therapy, but not different (p=0. 14) from the most recent median LVEF of 60% (IQR: 56-64%) after discontinuation of trastuzumab. Among 176 patients with serial LVEF data, 16 (9%) had 10% LVEF drop; 7 (44%) of these 16 patients had LVEF recovery. None of the cardiovascular risk factors prior to trastuzumab treatment including hypertension, diabetes, hyperlipidemia, peripheral arterial disease, coronary artery disease, and stroke were significantly associated with the development of TRCT. Conclusion: The incidence of clinically significant LVEF drop appears low in patients with advanced GI cancers as post-treatment LVEF recovery to baseline was observed at the population level. The value of using TTE to monitor TRCT in these patients with short OS should be further assessed in the perspective of cost effectiveness. Citation Format: Samual R. Kosydar, Matteo Castrichini, Mojun Zhu, Hao Xie. The value of routine trastuzumab-related cardiac toxicity monitoring in gastrointestinal cancers abstract. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts) ; 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84 (6Suppl): Abstract nr 6298.