Our group has showed type I polarized DC vaccine pulsed with HER2 peptides (HER2-DC1) generated strong anti-HER2 CD4+ T cell immunity in vaccinated HER2+ BC patients (Figure 2), as well in ER+/HER2+ and ER−/HER2+ BC patients, resulting in improved pathologic complete response in HER2+ DCIS and early BC patients (149, 150). This evidence concerns the gene ESR1 and breast cancer.