New perspectives on epigenetic modifications and PARP inhibitor resistance in HR-deficient cancers

The clinical treatment of DNA-repair defective tumours has been revolutionised by the use of poly(ADP) ribose polymerase (PARP) inhibitors. However, the efficacy of these compounds is hampered by resistance, which is attributed to numerous mechanisms including rewiring of the DNA damage response to favour pathways that repair PARP inhibitor-mediated damage. Here, we comment on recent findings by our group identifying the lysine methyltransferase SETD1A as a novel factor that conveys PARPi resistance. We discuss the implications, with a particular focus on epigenetic modifications and H3K4 methylation. We also deliberate on the mechanisms responsible, the consequences for the refinement of PARP inhibitor use in the clinic, and future possibilities to circumvent drug resistance in DNA-repair deficient cancers.

Automated summary

The clinical treatment of DNA-repair defective tumors has been revolutionized by PARP inhibitors. However, resistance to these compounds is a challenge due to the rewiring of the DNA damage response. Recent findings identify SETD1A as a novel factor that contributes to PARPi resistance, with implications for epigenetic modifications and H3K4 methylation. Mechanisms responsible, consequences for PARP inhibitor use, and future possibilities to overcome drug resistance in DNA-repair deficient cancers are discussed.