Through genome-wide and focused screening of PARP1 using CRISPR‒Cas9 technology, research has shown that the impaired cytotoxicity of PARPi in BRCA1-mutant triple-negative breast cancer (TNBC) and ovarian cancer cells was related to the loss or mutation of the PARP1 protein by abolishing PARP1 trapping. The gene discussed is BRCA1; the disease is ovarian carcinoma.