Leveraging homologous recombination repair deficiency in sarcoma.

Personalised oncology is at the forefront of cancer research. The goal of personalised oncology is to selectively kill cancer cells while minimising side effects on normal tissue. This can be achieved by identifying and targeting cancer vulnerabilities that distinguish it from normal cells. Many cancers are deficient in high-fidelity DNA repair pathways that maintain genomic stability, such as homologous recombination (HR). Such cancers are highly sensitive to targeted therapies that induce DNA damage or inhibit DNA repair pathways. A notable example and a poster child of personalised oncology are PARP1/2 inhibitors (PARPi) that selectively kill HR-deficient (HRD) cancer cells by preventing repair of DNA gaps or single-strand breaks (SSBs) (Slade, 2020). Inhibitors of cell cycle checkpoints such as CHK1 and WEE1 can also eliminate HRD cancers by pushing cancer cells through the cell cycle despite unrepaired DNA damage and causing death by mitotic catastrophe (Groelly et al, 2022). PARPi have been approved for the treatment of ovarian, breast, pancreatic, and prostate cancer but other cancer types with an HRD signature (HRDness) may also respond to PARPi treatment. Planas-Paz et al (2023) now show that many sarcomas show HRDness and respond to PARP1/2 and WEE1 inhibitors, thus offering a new personalised oncology approach for this treatment-refractory cancer.