Given its restricted expression of only a small subset of activated T and B cells in healthy adults [154], CD30 has been regarded as a safe and attractive tumor target compared to other pan-T cell markers, leading to the successful development of brentuximab vedotin, a CD30 antibody–drug conjugate, which is discussed in more detail later in this review [157,158,159,160]. The gene discussed is TNFRSF8; the disease is neoplasm.