Lacutamab is a first-in-class humanized monoclonal antibody targeting KIR3DL2, first studied in a phase I clinical trial including 42 patients with relapsed/refractory primary CTCL comprising 35 cases of Sézary syndrome (SS), 8 cases of mycosis fungoides (MF), and 1 case of primary CTCL not otherwise specified. The gene discussed is KIR3DL2; the disease is Sezary syndrome.