Abstract P1-15-02: Gene expression profiling of doxorubicin cardiotoxicity in peripheral blood cells of breast cancer patients
Authors: Todorova VK , Siegel ER , Makhoul I , Marquette M , Wei JY , Klimberg VS 
Published: May 2016

Abstract
Background: Doxorubicin (DOX), a widely used anti-cancer drug for treatment of breast cancer is known for its cardiotoxicity. DOX cardiotoxicity is cumulative-dose-dependent and begins with the first dose of chemotherapy. To date, no biomarker for early presymptomatic detection of DOX cardiotoxicity has been validated. Our previous data indicated that peripheral blood mononuclear cells (PBMCs) can be used as a surrogate tissue for identification of biomarkers for DOX cardiotoxicity. The aim of this study was to analyze PBMC gene expression induced by a single dose of DOX-based chemotherapy in breast cancer patients and correlated the data with DOX-induced cardiotoxicity.
Materials and Methods. Blood samples of 33 women treated for breast cancer with DOX-based chemotherapy were collected before the start and after the first cycle of chemotherapy. Total RNA was isolated from PBMC and whole-genome gene expression was performed using Illumina HumanHT-12 v4 Expression BeadChip array. Gene expression data were log2 – transformed and gene transcripts with average log2-intensities &gt; 7 were considered to be expressed. The group-specific means were analyzed via repeated-measures with ANOVA for expression changes after DOX. Genes with p-value&lt;0.05 were considered differentially expressed. Cardiac function was assessed before and after the completion of chemotherapy by echocardiogram and/or multigated acquisition scan. An absolute decrease of left ventricle ejection fraction &gt;10% or &lt;55% was considered abnormal. Differentially expressed genes (DEG) of patients who developed abnormal LVEF decrease were compared with DEG of patients who did not.
Results. A single dose of DOX-based chemotherapy resulted in 235 DEG in PBMC (P&lt;0.05, FDR&lt;0.05), mapped to cell death, oxygen transport and iron ion binding. Further analysis identified 87 DEG in the PBMC of eight (n=8) women who developed abnormal decline in LVEF from the baseline in comparison with women who did not (n=25). Most of the 87 DEG encode proteins secreted by activated neutrophils, such as alpha-defensins, arginase, cathepsin G, elastase, haptoglobin. The functional analysis of the 87 DEG showed enrichment for inflammatory response, immune response, cell death and peptidase activity.
Discussion. The results from this study indicated that elevated neutrophil-associated transcripts in the early stages of DOX-based chemotherapy were independent of the neutrophil count. These data suggest an association between the neutrophils activation after a single dose of DOX-based chemotherapy and later impairment of cardiac function. The early PBMC transcriptome signature can be used in the future development of biomarkers for DOX-associated cardiotoxicity.
Citation Format: Todorova VK, Siegel ER, Makhoul I, Marquette M, Wei JY, Klimberg VS. Gene expression profiling of doxorubicin cardiotoxicity in peripheral blood cells of breast cancer patients. [abstract]. In: Proceedings of the Thirty-Eighth Annual CTRC-AACR San Antonio Breast Cancer Symposium: 2015 Dec 8-12; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2016;76(4 Suppl):Abstract nr P1-15-02.