PDCD1 and neoplasm: Two groups, RT + IgG and HA PD-1 Ig + RT, received three consecutive fractions of radiation (20 Gy) specifically targeting the tumor, starting on day 1 (about 12 days after tumor cell inoculation), using a hypofractionated image-guided radiation therapy (IGRT) (Bandyopadhyay et al., 2016) operated on a small animal radiation research platform (SARRP) equipped with on-board cone beam computed tomography (CBCT) (Brodin et al., 2015) (Fig. 4A).