In this respect, the discovery that Tel prevents the proliferation of different BC cell lines acting as a model of primary and metastatic BC, while the proliferation of nontransformed cell lines is not affected by the antiviral together with the ability of Tel to synergistically work with both ET drugs (i.e., tamoxifen) and with the drugs used for the treatment of metastatic BC (e.g., abemaciclib and palbociclib) strongly indicate that Tel could be repurposed for the treatment of ERα‐expressing BCs. The gene discussed is ESR1; the disease is breast cancer.