Abstract 4119: Spatial mapping and molecular phenotyping of heterogeneous breast cancer lesions with multi-spectral short wave infrared emitting rare-earth nanoprobes

Abstract

Abstract Breast cancer is made up of distinct heterogeneous subpopulations that influence treatment responses. Currently, molecular phenotyping of a tumor involves post-biopsy histology, which makes quantification and assessment of spatial heterogeneity difficult. While there has been moderate success in radiographic imaging of heterogeneity, by PET and MRI, there is an urgent need for non-invasive imaging modalities to quantitatively index tumor heterogeneity in real-time. Our study utilizes rare earth(Re) nanoprobes which absorb near infrared radiation (980nm) and emit in the short wave infrared (SWIR) region (1000- 3000nm), allowing for improved tissue penetration and detection depth. We designed Re nanoprobes encapsulated in albumin to form Rare-Earth Albumin NanoComposites (ReANCs), which can be administered in vivo to target and detect deep tissue microlesions (~18mm3) at a depth of ~1cm. Additionally, ReANCs have been shown to detect multi-organ micro-lesions early and have excellent safety and tolerability profile. Albumin encapsulation not only creates a biocompatible nanoparticle, but also allows for increased biodistribution, pharmacokinetics, and the possibility of functionalization. Most notably, the availability of different Re dopants, Erbium and Thulium, with distinct emission spectral bands allows for accurate indexing of cellular subsets. In this study, we first demonstrate the ability of multi-spectral, ReANCs to distinguish and map a heterogeneous tumor lesion. 3D spheroids made of varying ratios of prelabeled populations of MDA-MB-231 cells (erbium-doped) and HCC1954 (thulium doped) were engineered and imaged to obtain a training set for spatial mapping of the different cell populations. Ratiometric analysis of the spheroids was performed to develop an algorithm for indexing. Subsequently, cancer-targeted ReANCs were engineered and target validation was performed in a 3D spheroid model followed by spatial mapping of targeted populations leading to ratiometric indexing of the different populations. Briefly, erbium doped ReANCs (MDA-MB-231 cells) and thulium doped ReANCs (HCC1954 cells), were deployed to detect distinct subpopulations in a 3D heterogeneous spheroid model of Her2+/- breast cancer. Images were obtained using in vitro microscopy platforms, using 980 nm excitation sources. Separate band-pass filters isolated emissions from the distinct REANC dopants, allowing for quantification of each pre-labeled cell in the training set. This was followed by development of an algorithm to find the percentage of subsets with unknown proportions allowing indexing of unknown subsets in a single tumor spheroid. This novel in vivo imaging modality forms the early basis for real-time on molecular aspects of the tumor and real-time tumor response tracking. Citation Format: Harini Kantamneni, Michael Donzanti, Xinyu Zhao, Shuqing He, Mei Chee Tan, Mark Pierce, Charles M. Roth, Shridar Ganesan, Vidya Ganapathy, Prabhas V. Moghe. Spatial mapping and molecular phenotyping of heterogeneous breast cancer lesions with multi-spectral short wave infrared emitting rare-earth nanoprobes [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 4119.