BRCA1/2 genetic background-based therapeutic tailoring of human ovarian cancer: hope or reality?

Abstract

Ovarian epithelial tumors are an hallmark of hereditary cancer syndromes which are related to the germ-line inheritance of cancer predisposing mutations in BRCA1 and BRCA2 genes. Although these genes have been associated with multiple different physiologic functions, they share an important role in DNA repair mechanisms and therefore in the whole genomic integrity control. These findings have risen a variety of issues in terms of treatment and prevention of breast and ovarian tumors arising in this context. Enhanced sensitivity to platinum-based anticancer drugs has been related to BRCA1/2 functional loss. Retrospective studies disclosed differential chemosensitivity profiles of BRCA1/2-related as compared to "sporadic" ovarian cancer and led to the identification of a "BRCA-ness" phenotype of ovarian cancer, which includes inherited BRCA1/2 germ-line mutations, a serous high grade histology highly sensitive to platinum derivatives. Molecularly-based tailored treatments of human tumors are an emerging issue in the "era" of molecular targeted drugs and molecular profiling technologies. We will critically discuss if the genetic background of ovarian cancer can indeed represent a determinant issue for decision making in the treatment selection and how the provocative preclinical findings might be translated in the therapeutic scenario. The presently available preclinical and clinical evidence clearly indicates that genetic background has an emerging role in treatment individualization for ovarian cancer patients.

Figure 1

DNA repair defects and therapeutic intervention in BRCA1/2 defective tumors. Following DNA damage poly(ADP-ribose) polymerases (PARP), specifically PARP-1 and PARP-2, are activated and bind to the exposed Single Strand Breaks (SSBs). Pharmacological inhibition of PARP1 with PARP-inhibitors leads to a block in the repair of SSBs, resulting in the blockage of replication fork and subsequent conversion of damage in DSBs. In hereditary cancers harboring BRCA1/BRCA2 mutations, this system is inefficient and therefore the tumor cells lacking this survival mechanism undergo cell death. The antitumor activity of PARP inhibitors may be enhanced by combination with chemotherapeutic agents which induce direct damage to DNA, such as platinum derivatives.