Abstract
Homologous recombination deficiency (HRD) is a common phenotypic alteration that is highly druggable with poly (ADP-ribose) polymerase inhibitors (PARPi). Although BRCA1/2 gene mutations are among the commonest genomic aberrations associated with HRD, defects in other DNA damage repair (DDR) genes also may influence clinical response to PARPi. Here, we report the case of a 51-year-old Chinese woman with extensive symptomatic brain metastases from metastatic BRCA1/2 wild-type triple-negative breast cancer (TNBC). Comprehensive genomic profiling (CGP) of resected central nervous system tumor revealed mutations in TP53 and multiple DDR pathway genes, suggesting an HRD phenotype. The patient showed a rapid and remarkable response to single-agent niraparib, and her improved condition remained stable for > 8 weeks. To the best of our knowledge, this is the first report of the use of CGP for guiding targeted therapy with PARPi in patients with TNBC, for which options have been limited. CGP may have an increasingly impactful role to predict clinical response of PARPi in patients with BRCA1/2 wild-type TNBC.