Response to PARP Inhibitor Predicted by the RAD51 Assay

Summary

In tumors with a defect in the homologous recombination (HR) pathway, double-strand break repair is partly impaired. Patients with HR deficient tumors benefit from therapies that induce DNA lesions requiring HR for repair. These therapies include platinum compounds and inhibitors of the enzyme PARP-1. At this moment, selection for PARP inhibitor treatment relies on detection of germ-line or somatic mutations in the HR pathway genes BRCA1 or BRCA2. However, not all HR deficient tumors have a BRCA gene mutation, the BRCA genes can also be silenced by promoter methylation. Moreover, the HR pathway can be defective due to mutations in other HR genes. In addition, the presence of a BRCA gene mutation does not guarantee defective HR since mutations in other genes (e.g. TP53BP1) can restore HR despite the presence of a BRCA1 mutation. Since all patients with tumors that are HR deficient may benefit from PARP inhibition, better tools are required to identify these patients. Recently, a functional ex vivo test for HR deficiency (the RAD51 assay) became available for clinical use. The RAD51 assay can identify patients with functional defects in HR-repair and may predict which cancer patients are likely to benefit from PARP inhibition. The purpose of this study is to investigate whether the RAD51 assay can select patients who will benefit from treatment with the PARP-inhibitor veliparib.

Timeline

Start

2019-11

Primary completion

2020-11

Completion

2020-11

Drugs

Indications