PARP1 and cancer: Although breast and ovarian cancers with mutations in BRCA1/2 demonstrate exquisite sensitivity to PARPi, these cancers represent a relatively small subset of cancers.[96] However, niraparib (Zejula®) also showed significant benefit in patients with functional HR repair capability, indicating that there are likely potential biomarkers and mechanisms that may provide sensitivity towards PARP inhibition in addition to HR pathway genes.[12]