Abstract 5013: Rapid generation of phenomic and functional profiles of patient-derived 3D cell culture models for identification of treatment vulnerabilities of breast cancer: Early results of the EFRE-PoP project
Authors: Kiver Verena I. , Gambara Guido , Gorea Olga , Blohmer Jens-Uwe , Jurmeister Philipp , Denkert Carsten , Silvestri Alessandra , Schweiger Caroline M. , Silvestrov Maxine , Keilholz Ulrich , Regenbrecht Christian R. 
Published: August 2018

Abstract
Targeted treatment for breast cancer subsets currently relies on the occurrence of estrogen, progesterone and Her2/neu receptors. For triple negative breast cancer (TNBC) there is no identified targeted therapy. The mutational landscape for breast cancer subsets has been characterized, but drug development has been limited due to the lack of appropriate preclinical models. Development of patient-derived xenograft models (PDX) has been difficult with take rates of below 30%.To establish a series of patient-derived 3D (PD3D) cell culture models as a versatile resource for ex vivo drug sensitivity screens as well as secondary establishment of PDX. We obtained breast cancer specimens either by biopsy or surgical resection. Upon arrival tumor tissue was minced and enzymatically digested. After subsequent filtering, respective tissue size fractions were seeded as Matrix-droplets into 24-well plates and incubated under standard conditions. Growth of PD3Ds was monitored daily by microscopy. PD3Ds were splitted when their diameter reached appropriate size. Organoids were than fixed and embedded. FFPE sections of donor-tissues and derived PD3D models were than used for IHC and inspected by a pathologist. In parallel, mutational profiling of snap-frozen tumor tissue and cell cultures was performed. All models were subjected to a semi-automated multi-drug response assay in a 384-well format to assess individual compound sensitivities.We established a scalable workflow for culturing and screening of PD3D cell cultures from limited quantities of breast cancer tissue from true-cut and vacuum biopsies as well as surgical specimen. Tissue fragments of ca. 3mm in diameter were sufficient to successfully establish PD3D cell cultures at a high yield. The time needed to expand PD3D cell cultures to obtain a sufficient amount of cells for subsequent molecular analyses varies from 2-6 weeks depending on amount and quality of samples as well as grade and stage of the donor tumor tissue. At the time, we can report a rate of culture establishment rate of 75% (11 models from 15 patient samples) for various clinical relevant subgroups, including TNBC, HR+, Her 2 pos. BC and one DCIS sample. The immunohistology and mutational profiles of these samples are currently being confirmed. The established workflow for culturing PD3D cell cultures offers high yield rates within a potentially clinically relevant time-frame for HTP cytotoxicity screenings. We are encouraged that this method is suitable for various molecular subtypes of breast cancer. Once adequately validated in co-clinical trials, PD3D models would make for an intriguing tool in supporting clinical decision-making for individual patients. Particularly patients with breast cancer refractory to standard of care compounds could benefit from this approach.
Citation Format: Verena I. Kiver, Guido Gambara, Olga Gorea, Jens-Uwe Blohmer, Philipp Jurmeister, Carsten Denkert, Alessandra Silvestri, Caroline M. Schweiger, Maxine Silvestrov, Ulrich Keilholz, Christian R. Regenbrecht. Rapid generation of phenomic and functional profiles of patient-derived 3D cell culture models for identification of treatment vulnerabilities of breast cancer: Early results of the EFRE-PoP project [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 5013.