In a study by Pelekanou et al. involving 113 HR+ and 37 ER- patients who underwent tumor biopsies at baseline and two cycles of neoadjuvant chemotherapy (NAC), gene mapping analysis and quantification of tumor-infiltrating lymphocytes (TILs), FOXP3+ T cells, and CD163+ TAMs, were conducted. The gene discussed is ESR1; the disease is neoplasm.