Germline Mutations of Holliday Junction Resolvase Genes in Multiple Primary Malignancies Involving Lung Cancer Lead to PARP Inhibitor Sensitization

Abstract Purpose: The incidence of multiple primary malignancies (MPM) involving lung cancer has increased in recent decades. There is an urgent need to clarify the genetic profile of such patients and explore more efficacious therapy for them. Experimental Design: Peripheral blood samples from MPM involving patients with lung cancer were assessed by whole-exome sequencing (WES), and the identified variants were referenced for pathogenicity using the public available database. Pathway enrichment analysis of mutated genes was performed to identify the most relevant pathway. Next, the effects of mutations in relevant pathway on function and response to targeted drugs were verified by in vitro and in vivo experiments. Results: Germline exomes of 71 patients diagnosed with MPM involving lung cancer were sequenced. Pathway enrichment analysis shows that the homologous recombination repair (HRR) pathway has the strongest correlation. Moreover, HRR genes, especially key Holliday junction resolvases (HJR) genes (GEN1, BLM, SXL4, and RMI1), were most frequently mutated, unlike the status in the samples from patients with lung cancer only. Next, we identified a total of seven mutations in HJR genes led to homologous recombination DNA repair deficiency and rendered lung cancer cells sensitive to PARP inhibitor treatment, both in vitro and in vivo. Conclusions: This is the first study to map the profile of germline mutations in patients with MPM involving lung cancer. This study may shed light on early prevention and novel targeted therapies for MPM involving patients with lung cancer with HJR mutations.