V Scholar Plus Award – extended funding for exceptional V Scholars
Estrogen receptor positive (ER+) metastatic breast cancer (MBC) remains the most common cause of breast cancer death. Though we have made many advances in the treatment of ER+ MBC, patients invariably develop resistance to therapies. The mechanisms of resistance are not well known. In order to improve survival for patients with ER+ MBC, it is critical to develop an understanding of this resistance.
We recently found that in 7% of metastatic tumors from patients with resistant ER+ MBC, a gene called the retinoblastoma tumor suppressor (Rb) had been deleted. Loss of the Rb gene resulted in resistance to multiple agents used for ER+ MBC. ER+ MBC that lacks Rb likely represents a growing subset of patients in whom standard therapies do not work and in whom we do not know the optimal therapies. Therefore, it is critical to develop novel approaches to treating this subtype of ER+ MBC.
The goal of this research is to better understand Rb loss in ER+ MBC and identify new therapeutic strategies. To do this, we will utilize cell line models we have generated that approximate ER+ MBC that has lost the Rb gene. We will characterize these cell lines to identify how they become resistant to therapies, and identify novel therapeutic targets to prevent or overcome this resistance. At the completion of the project, our results should enable the development of clinical biomarkers of response and resistance for patients with ER+ MBC, and, ultimately, the design of clinical trials of therapeutic approaches and rational drug combinations.