ERBB2 and breast cancer: For example, in a study of 40 patients with breast cancer, those who had HER2-reactive T cells and a lower proportion of Myeloid derived suppressor cells (MDSCs) before treatment exhibited a 100% rate of survival after 5 years, compared to 38% survival among patients without HER2-reactive T cells and higher frequencies of MDSCs (p = 0.03).