Poly (ADP-ribose) polymerase inhibitors (PARPi) are revolutionary drugs, effective in treating ovarian, breast, pancreatic and prostate cancers.
Multiple randomised clinical trials demonstrated efficacy of different drugs from PARPi family, such as Olaparib, Niraparib, Rucaparib and Talazoparib. Despite high efficiency, only a subset of patients truly benefit from the therapy. Some of them carry BRCA1/2 genes mutations, an excellent indicator of Homologous Recombination Deficiency (HRD), the best understood mechanism leading to PARPi sensitivity. However, clinical trials have demonstrated that patients who don’t carry BRCA mutations can also benefit from PARPi. For example, the PRIMA trial showed, that assessing HRD status can channel patients with no BRCA1/2 mutations into successful PARPi treatment. The PRIMA trial also showed that significant proportion of patients without BRCA1/2 mutation or HRD also respond to PARPi. This indicates that current diagnostics for PARPi is not efficient for patient selection.