None of the 3 responders’ cancers in the PIKTOR/cis/nab pac trial harbored a PIK3CA mutation in their pre-PIKTOR biopsies, and patient 1 had a germline BRCA1 mutation, although this PARP inhibitor-pretreated patient’s pre- and post-PIKTOR biopsies did not demonstrate somatic BRCA1 loss of heterozygosity. This evidence concerns the gene BRCA1 and cancer.