At the higher dose levels of anti-4-1BB mAb (1 and 5 mg/kg), AST and ALT levels were elevated over twofold what was reported with anti-4-1BB monotherapy and the combination intensified anti-4-1BB-induced neutropenia, lymphopenia, and thrombocytopenia. The gene discussed is TNFRSF9; the disease is Decreased total neutrophil count.