Abstract PO1-24-07: LYSOSOMAL-ASSOCIATED TRANSMENBRANE 4B (LAPTM4B) AS POTENTIAL BIOMARKER IN BREAST CANCER

Abstract LAPTM4B is a transmembrane that promotes autophagy and renders tumor cells resistant to metabolic and genotoxic stress. Increased expression of LAPTM4B has been found in breast, liver, lung, ovarian, uterine and gastric cancers. Overexpression of LAPTM4B contributes to chemotherapy resistance, proliferation and metastases. We analyze the expression of LAPTM4B in serum by ELISA method in a series of breast cancer patients in different clinical situations to assess its possible potential as a biomarker. A total of 135 patients were analyzed, 95 patients were in early breast cancer and 50 in metastatic disease. Of the 95 patients with early disease, 52 had a luminal A phenotype, 19 luminal B, 15 HER2 positive and 9 triple negative. And of the other 50 they were luminal in 34, HER2 positive in 11 and triple negative in 5. The attached table specifies the values of the LAPTM4B expression in the different clinical situations. GLOBAL LUMINAL A LUMNAL B HER2 TRIPLE NEGATIVE SITUATIONS Laptm4b n Laptm4b n Laptm4b n Laptm4b n Laptm4b n EARLY 9,6 ng/ml 95 7,7 ng/ml 52 12,8 ng/ml 19 13,4 ng/ml 15 7,1 ng/ml 9 METASTATIC 16,8 ng/ml 50 13,7 ng/ml 34 7,2 ng/ml 11 58,9 ng/ml 5 We found a statistic difference in the expression of LAPTM4B in patients with early and metastatic disease (ANOVA test p:0,028 ). LAPTM4B was higher in the luminal B and HER2 subtypes in early breast cancer while in metastatic disease was overexpressed in triple negative. An interesting finding was that in metastatic disease, LAPTM4B was overexpressed in patients with progression compared to patients in response. 30 ng/ml vs 10 ng/ml (ANOVA test p:0,011) LAPTM4B expression may be a potential biomarker in breast cancer since its expression is statistically different in early and metastatic disease (9,6 vs 16,8 ng/ml).In addition, patients with metastatic breast cancer who re in response also have lower levels of LAPTM4B compared with patients in progression. Monitoring the levels of LAPTM4B in serum can help us to predict the treatment response. Citation Format: Serafin Morales Murillo, Ariadna Gasol Cudós, Noemí Tuset Der-Abrain, Izaskun Urdanibia, Ana Velasco Sánchez. LYSOSOMAL-ASSOCIATED TRANSMENBRANE 4B (LAPTM4B) AS POTENTIAL BIOMARKER IN BREAST CANCER [abstract]. In: Proceedings of the 2023 San Antonio Breast Cancer Symposium; 2023 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2024;84(9 Suppl):Abstract nr PO1-24-07.