The expansion of CD4 Tregs in HER2+ tumors, may explain the effectiveness of targeted therapies such as Traztuzumab that are known to modulate Treg activity 54, and highlights the need to identify additional therapies targeting Treg activity given that CD4 Tregs are known to promote an immunosuppressive TME that can lead to tumor escape 55. The gene discussed is CD4; the disease is neoplasm.