For example, researchers used CRISPR-CAS9-mediated PD-1 knockout CAR-T cells against mesothelin, a glycosylphosphatidylinositol- anchored cell surface receptor that is overexpressed in TNBC and contributes to tumor invasion, metastasis, and drug resistance (Table 1; Table 3) [92]. The gene discussed is PDCD1; the disease is neoplasm.