Revival and Recharacterization of a Preclinical Model of Hormone-Dependent Breast Cancer to Study Immunotherapy.

Immune checkpoint inhibitors have yet to significantly improve outcomes for hormone-dependent estrogen/progesterone receptor-positive breast cancer. To address this issue, there is a need for murine models that more closely mimic hormone receptor-positive breast cancer. In this issue, Gil Del Alcazar and colleagues provide an in-depth characterization of a Nitroso-N-methylurea-induced mammary tumor model in outbred Sprague-Dawley rats that meets these needs as it mimics the heterogeneity for mutational profiles, estrogen receptor expression, and immune evasive mechanisms observed in human breast cancer. See related article by Gil Del Alcazar et al., p. 680 (1).