The antibody–drug conjugate brentuximab vedotin (BV), targeting CD30-positive cells, has been approved for the treatment of relapsed or refractory (R/R) systemic anaplastic large cell lymphoma (sALCL), and primary cutaneous anaplastic large cell lymphoma or mycosis fungoides in patients who have received previous systemic therapy. The gene discussed is TNFRSF8; the disease is mycosis fungoides.