PDCD1 and neoplasm: The two‐tumor‐bearing mice were randomly divided into six groups when the primary tumor (left tumor) volume reached 100 mm3 (n = 4 in each group), including 1) untreated group, PBS (−); 2) the group treated with PBS plus X‐ray irradiation, PBS (+); 3) the group treated with anti‐PD‐1 antibody plus X‐ray irradiation, PD‐1 (+); 4) the group treated with Hb@Hf‐Ce6 NPs plus X‐ray irradiation, NP (+); 5) the group treated with Hb@Hf‐Ce6 NPs plus anti‐PD‐1 antibody, NP+PD‐1 (−); 6) the group treated with Hb@Hf‐Ce6 NPs plus anti‐PD‐1 antibody with X‐ray irradiation, NP+PD‐1 (+).