PDCD1 and neoplasm: The RT + HA PD-1 Ig group showed a significant tumor growth delay (TGD) as compared to RT + IgG and the control groups (IgG or HA PD-1 Ig) (Fig. 4D), and a significantly lower tendency to develop secondary tumors (15% vs 83% in RT + HA PD-1 Ig and RT + IgG mice, respectively) in the distal inguinal LN (Fig. 4E) at 30 days post-treatment.