Targeting Germline- and Tumor-Associated Nucleotide Excision Repair Defects in Cancer.

Purpose: Nucleotide excision repair (NER) gene alterations constitute potential cancer therapeutic targets. We explored the prevalence of NER gene alterations across cancers and putative therapeutic strategies targeting these vulnerabilities.

Experimental Design: We interrogated our institutional dataset with mutational data from more than 40,000 patients with cancer to assess the frequency of putative deleterious alterations in four key NER genes. Gene-edited isogenic pairs of wild-type and mutant or cell lines were created and used to assess response to several candidate drugs.

Results: We found that putative damaging germline and somatic alterations in NER genes were present with frequencies up to 10% across multiple cancer types. Both and studies showed significantly enhanced sensitivity to the sesquiterpene irofulven in cells harboring specific clinically observed heterozygous mutations in or . Sensitivity of NER mutants to irofulven was greater than to a current standard-of-care agent, cisplatin. Hypomorphic -mutant cells had impaired ability to repair irofulven-induced DNA damage. Transcriptomic profiling of tumor tissues suggested codependencies between DNA repair pathways, indicating a potential benefit of combination therapies, which were confirmed by studies.

Conclusions: These findings provide novel insights into a synthetic lethal relationship between clinically observed NER gene deficiencies and sensitivity to irofulven and its potential synergistic combination with other drugs..