To circumvent some of the limitations posed by the lack of appropriate animal models in preclinical studies of immunotherapies, partially human leukocyte antigen-matched TNBC PDX tumor lines from our collection, as well as human melanoma cell lines, were engrafted in humanized nonobese diabetic/severe combined immunodeficiency IL2Rγnull (hNSG) mice obtained by intravenous injection of CD34+ hematopoietic stem cells into nonlethally irradiated 3–4-week-old mice. The gene discussed is CD34; the disease is melanoma.