PDCD1 and neoplasm: The administration of NHS-muIL12 at doses ranging from 1-2 μg reduces tumor growth, but the regression is transient probably due to (1) little necrotic areas in s.c. tumors at 7-10 days post-inoculation, thus limiting tumor targeting of the NHS-muIL12, and/or (2) local IFN-γ production that reignites the PD-1/PD-L1 immunosuppressive axis.