Its antitumor efficacy is context-dependent: in osteosarcoma mice, oral L-Arg (2 g/kg/day) expands splenic CD8+ T cells/TILs and elevates serum IFN-γ; combining with α-PD-L1 reduces PD-1+ exhausted TILs by 40% and prolongs median OS (124). Here, CD8A is linked to osteosarcoma.