CD7 is a type-I transmembrane glycoprotein belonging to the immunoglobulin superfamily. CD7 is one of the earliest surface markers to be expressed on the surface of developing T cells and its expression is maintained throughout maturation of multiple T cell subsets and NK cells. Engagement of CD7 through binding its ligand, SECTM1, has been shown to promote tyrosine phosphorylation of its cytoplasmic domain, recruitment of PI3K, and delivery of costimulatory signals for T cell activation. While CD7 is expressed on normal T cells, it is also highly expressed in a variety of T cell malignancies, which has poised it as a potential target of immunotherapy.