To model FLRT3-expressing cancer in a cell line–derived xenograft (CDX) tumor model, we intradermally implanted 293T cells that ectopically expressed FLRT3 in NOD.Cg-Prkdc scid Il2rg tm1Wjl/SzJ (NSG) mice with adoptively transferred human PBMCs. Here, FLRT3 is linked to cancer.