Clustered regularly interspaced short palindromic repeats/CRISPR-associated nuclease9 (CRISPR/Cas9) gene editing technology, which can recognize the target genome sequence with single-strand guide RNA (sgRNA) and guide the Cas9 protease to knock down the target gene, has occupied a central position in further optimizing anti-PD-1/PD-L1 tumor immunotherapy 68, 85-87. The gene discussed is PDCD1; the disease is neoplasm.