By looking at T cell subsets in ER+ and ER- breast cancer subtypes, they could determine that most of the analyzed ER- and some subsets of ER+ breast tumors had a higher infiltration of T-regs and high PD-1 + CTLA4+ expressing T cell subsets, indicating that these tumor subtypes could respond well to neoadjuvant immunotherapy utilizing checkpoint inhibitors [50]. This evidence concerns the gene ESR1 and breast cancer.