Response to PARP inhibitor in EGFR-tyrosine kinase inhibitor-resistant metastatic lung adenocarcinoma with germline PALB2 mutation

Tumors with homologous recombination deficiency (HRD) can benefit from treatment with poly ADP-ribose polymerase inhibitors (PARPi). However, the methods for identifying HRD vary and are controversial. Several DNA repair genes in the homologous recombination repair pathway may be linked to PARPi susceptibility, and studies are underway to identify biomarkers that can predict the response to PARPi. We present a case of EGFR-tyrosine kinase inhibitor-resistant metastatic lung adenocarcinoma with a germline PALB2 mutation that was treated with fluzoparib (an orally administered PARPi). The treatment achieved surprising results and lasted for more than 4.5 months. Our study provided evidence that metastatic lung adenocarcinoma with germline PALB2 could benefit from PARPi, which improves patient outcomes.