Abstract P1-03-06: Development of patient-derived xenograft tumor models and 3D spheroid culture from advanced hormone receptor-positive inflammatory breast cancer patients for evaluation of new therapeutics
Authors: Qiang Wenan , Zhong Zhangfeng , Monahan Pamela , Tse Kristy , Zhang Youbin , Zhang Qiang , Gerratana Lorenzo , Davis Andrew , Gursel Demirkan , Bleher Reiner , Wei Jian-Jun , James Charles D. , O’Halloran Thomas V. , Cristofanilli Massimo 
Published: March 2020

Abstract
Background: Breast cancer (BC) is a heterogeneous disease comprising different clinical, histopathological, and molecular subtypes. Hormone receptor-positive (HR+) advanced BC cancer, in particular the inflammatory BC (IBC) represents a significant clinical challenge because of the development of endocrine resistance during either adjuvant or metastatic treatment translating to poor outcome. We aim to develop unique PDX tumor models and 3D spheroid/organoid cultures that recapture advanced IBC using pleural effusions or/and circulating tumor cells (CTCs) as tumor resource and that can help understand the mechanism of IBC metastasis for new drug development. Methods: Five samples of pleural effusion-derived tumor cells or circulating tumor cells (CTCs) from three advanced IBC patients were obtained from Northwestern Memorial Hospital to establish IBC PDX tumor model in immunodeficient NSG female mice via subcutaneous or breast fat pad xenografting and develop the derived 3D organoid/spheroid cultures for anti-cancer drug evaluation. STR profiling against with original patient tumor DNA was conducted to confirm the tumor authentication. Results: Three developed IBC PDX tumor models (one HR+-IBC and two triple negative (TN)-IBC) were demonstrated by pathology to have highly heterogeneous characteristics and metastatic features similar to the original patient tumor. NSG mice xenografted with original TN-IBC pleural effusion, or derived spheroid cultures with varying passage numbers (&lt;3 passages or &gt;6 passages) manifested different inflammatory clinical symptoms. Mice xenografted with one case of original TN-IBC pleural effusion cells (~40% of tumor-associated macrophages and ~60% of tumor cells) developed palpable tumors and was shown to have the most IBC-like characteristics including reddish skin and ulcerative lesions. They were sacrificed 2 months after xenograft due to declining health. Mice xenografted with &gt;6 passages or &lt;3 passages of spheroid cultures manifested little to moderate skin lesions and developed tumor sizes of ~1 cm within 2-3 months while having a longer life span. Liver and lung metastases were observed in the breast fat pad of xenografted PDX tumor mice with one case of original HR+-IBC pleural effusion. 3D tumor spheroid/organoid cultures were successfully established from original IBC pleural effusion or/and IBC PDX tumor cultures. Spheroid generated from HR+-IBC pleural effusion showed phenotypic plasticity: the HR+-IBC spheroid cells display both tumor and macrophage cell characteristics and spheroid cultures can convert to adhesive cell phenotypes with addition of condition media. These spheroid/organoid cultures are used for evaluation of new drug strategies such as selectively targeting ER degraders (SERDS), CDK4/6 inhibitor, or Tyrosine kinase inhibitors for treatment of HR+-IBC or TN-IBC. Conclusions: Our results suggested 3D spheroid cultures and PDX tumor models from advanced IBC recapture aggressive features of the disease and can be an ideal model for the mechanism study of metastatic advanced IBC and preclinical testing of novel agents in IBC and endocrine resistant disease.
Citation Format: Wenan Qiang, Zhangfeng Zhong, Pamela Monahan, Kristy Tse, Youbin Zhang, Qiang Zhang, Lorenzo Gerratana, Andrew Davis, Demirkan Gursel, Reiner Bleher, Jian-Jun Wei, Charles D. James, Thomas V. O’Halloran, Massimo Cristofanilli. Development of patient-derived xenograft tumor models and 3D spheroid culture from advanced hormone receptor-positive inflammatory breast cancer patients for evaluation of new therapeutics [abstract]. In: Proceedings of the 2019 San Antonio Breast Cancer Symposium; 2019 Dec 10-14; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2020;80(4 Suppl):Abstract nr P1-03-06.