To validate our findings, we used other commercially available TMAs of patients with relapsed ER+ breast cancer (80 patients, cores of 54 patients passed quality criteria), HER2+ breast cancer (40 patients, cores of 38 patients passed quality criteria), and TNBC (50 patients, cores of 26 patients passed quality criteria) (Figure S11; Table S5), and performed PhenOptics multiplex histology with our selected markers. The gene discussed is ESR1; the disease is breast cancer.