The differential benefit that ovarian cancer patients derived from niraparib monotherapy, coupled with the observation that niraparib treatment caused tumor regressions in two NSCLC patients (42), compelled us to compare niraparib activity in isogenic cell lines lacking either BRCA2 or ATM and to assess niraparib efficacy in a panel of NSCLC PDX models containing biallelic mutations in ATM and other HRR genes. The gene discussed is ATM; the disease is ovarian cancer.