Abstract P6-01-38: Predictive efficacy biomarker for chemotherapy agents against triple-negative breast cancer bioprinted organoid tumors (BOTs) using solid tumor biopsy-on-a-chip
Authors: Bollenbecker Seth , Patel Zeelu , Punjani Zeenia , Charania Areesha , Patel Heli , Abbott Alyssa , Kunkle Kaitlyn , Sewell-Loftin Mary Kathryn , Grossman Gregory , Budhwani Karim 
Published: March 2023

Abstract
Background: Despite $90 billion in preclinical research and clinical trials every year, 90% of cancer clinical trials are unsuccessful. Thus, there is considerable interest in predicting clinical efficacy of preclinical formulations early in discovery using patient derived ex vivo platforms. However, extracting adequate tissue for such models can be difficult depending on tumor type and site. Dominant mechanisms for expanding patient tissue include xenografts and organoids. However, the former imposes a large time window to establish while the latter is constrained in space by sizescales. Here, we present a novel approach for expanding TNBC tissue, specifically for use in ex vivo models, that addresses these constrains with 3D bioprinted organoid tumors (BOTs). Objective: The aim of this study is to generate TNBC BOTs that mimic core biopsy tissue for use in ex vivo precision and personalized predictive biomarkers for chemotherapies. Methods: BOTs were generated using alginate-based bioink prepared with MDA-MB-231 TNBC cells. Briefly, specially prepared fresh TNBC bioink was deposited layer-by-layer using a Cellink BIO X6 bioprinter in geometrical configurations to mimic 14- to 18- gauge tumor biopsies. These were chemically cross-linked and cured in stages to allow cells and matrix to self-assemble with limited degrees of freedom. Fully cured BOTs were loaded in our ex vivo solid tumor biopsy-on-a-chip and treated with chemotherapy agents to evaluate sensitivity and resistance, with outcomes determined using immunofluorescent live and dead cell staining methods. Results: A 3-minute crosslinking time with calcium chloride provided a stable and functional sodium alginate medium for treating cellular BOTs. Two layers of TNBC bioink was determined to be the optimal size and shape for compatibility with our ex vivo biopsy-on-a-chip predictive efficacy biomarker platform. TNBC cells were verified to be evenly distributed within the cured sodium alginate matrix using live cell nuclear stains. Successful diffusion of multiple agents to spatially distinct regions of the bioprinted tissue was verified with fluorescently labeled small molecules and nucleic acid stains up to 200 µM deep. Impact: Patient derived BOT core mimics and other configurations could be used in ex vivo breast cancer chemotherapy screening models to obtain sensitivity and resistance profiles as predictive functional biomarkers both on the bedside for personalized treatment strategy development and on the bench to uncover new therapeutic targets. Due to their potential to replicate biophysical and biochemical characteristics of a tumor and its microenvironment, BOT based precision and personalized medicine platforms can provide more accurate drug efficacy readout compared to in vitro cancer models.
Citation Format: Seth Bollenbecker, Zeelu Patel, Zeenia Punjani, Areesha Charania, Heli Patel, Alyssa Abbott, Kaitlyn Kunkle, Mary Kathryn Sewell-Loftin, Gregory Grossman, Karim Budhwani. Predictive efficacy biomarker for chemotherapy agents against triple-negative breast cancer bioprinted organoid tumors (BOTs) using solid tumor biopsy-on-a-chip [abstract]. In: Proceedings of the 2022 San Antonio Breast Cancer Symposium; 2022 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2023;83(5 Suppl):Abstract nr P6-01-38.