A second therapeutic approach would be cell-based treatment that utilizes T-cell receptor (TCR)-engineered T cells to target ESR1 peptides, as has been done for gp100 and MART-1 peptides in the setting of metastatic melanoma (50) and for MAGE-A4 peptide in the setting of esophageal cancer (7). Here, PMEL is linked to metastatic melanoma.