Abstract B015: A novel Cluster 3 Endometrial Cancer PDX model to test hormone therapy regimens

Abstract Endometrial cancer is the most commonly diagnosed gynecologic cancer and continues to rise in incidence and mortality rates worldwide. With the evaluation of large datasets including the TCGA, endometrial cancers have been subdivided into four different cluster groups based on molecular characteristics. The most common subtype of endometrial cancer is the Cluster 3 category, demarcated by the expression of estrogen receptors (ER) and progesterone receptors (PR) with the potential to respond to hormonal therapy. However, Cluster 3 tumors frequently lose hormone receptor expression over time, particularly PR, making them resistant to treatment. Although numerous cell line models exist to study this disease, there is a need for improved models to select best treatment options for the specific types of endometrial cancers. Here, we describe the development of an endometrial cancer patient derived xenograft (PDX), EC-PDX3. The initial tumor from which EC-PDX3 was derived was a low-grade endometrioid endometrial carcinoma that contained a low number of somatic copy number alterations. The tumor initially tested robustly positive for both ER and PR in the donor patient as well as in initial passages in athymic mice, making this model valuable for hormone therapy research. In these studies, EC-PDX3 cells were grown within immunodeficient NSG mice. We performed H 2023 Nov 16-18; Boston, Massachusetts. Philadelphia (PA): AACR; Clin Cancer Res 2024;30 (5Suppl): Abstract nr B015.