Sparks et al, Heterogeneity in tumor chromatin-doxorubicin binding revealed by in vivo fluorescence lifetime imaging confocal endomicroscopy: MATLAB code

Abstract

Abstract We present an approach to quantify drug-target engagement using in vivo fluorescence endomicroscopy, validated with in vitro measurements. Specifically, we demonstrate that doxorubicin binding to chromatin causes a change in the fluorescence lifetime of histone-GFP fusions that can be measured in vivo at single cell resolution using a confocal laparo/endomicroscope. We measure both intra- and inter-tumor heterogeneity in doxorubicin chromatin engagement in a model of peritoneal metastasis of ovarian cancer, revealing striking variation in the efficacy of doxorubicin-chromatin binding depending on intra-peritoneal or intra-venous delivery. In addition, we observe significant variations in doxorubicin-chromatin binding between different metastases in the same mouse and between different regions of the same metastasis. The quantitative nature of fluorescence lifetime imaging enables direct comparison of drug target engagement for different drug delivery modalities and between in vitro and in vivo experiments. This uncovers dramatically different rates of cell killing for the same level of doxorubicin binding in vitro and in vivo.

Abstract We present an approach to quantify drug-target engagement using in vivo fluorescence endomicroscopy, validated with in vitro measurements. Specifically, we demonstrate that doxorubicin binding to chromatin causes a change in the fluorescence lifetime of histone-GFP fusions that can be measured in vivo at single cell resolution using a confocal laparo/endomicroscope. We measure both intra- and inter-tumor heterogeneity in doxorubicin chromatin engagement in a model of peritoneal metastasis of ovarian cancer, revealing striking variation in the efficacy of doxorubicin-chromatin binding depending on intra-peritoneal or intra-venous delivery. In addition, we observe significant variations in doxorubicin-chromatin binding between different metastases in the same mouse and between different regions of the same metastasis. The quantitative nature of fluorescence lifetime imaging enables direct comparison of drug target engagement for different drug delivery modalities and between in vitro and in vivo experiments. This uncovers dramatically different rates of cell killing for the same level of doxorubicin binding in vitro and in vivo.