PARP Inhibitors for the Treatment of Ovarian Cancer.

The standard of treatment for advanced ovarian cancer is represented by optimal surgical debulking preceded or followed by chemotherapeutic regimens including taxanes and platinum agents, possibly associated with bevacizumab and/or intraperitoneal therapy. Despite this comprehensive treatment strategy, almost 75% of patients relapse or progress and are therefore candidates for a second-line treatment, showing, at this point, less chemo-sensitivity and worse prognosis. An interesting approach to improve outcomes of these patients has been developed in the last decade, in BRCA-related ovarian cancer. Mutations in one of the BRCA genes result in impaired homologousrecombination DNA repair, which causes genetic abnormalities that promote carcinogenesis. Interestingly, this defect has been exploited by the introduction of poly (ADP-ribose) polymerase (PARP) inhibitors to provide specific cancer cell cytotoxicity. Particularly, the inhibition of PARP in BRCAmutation carriers leads to the persistence of DNA damage usually repaired by the homologousrecombination system, resulting in cell cycle arrest and thus apoptosis. Despite the mechanism of action, an activity of PARP inhibitors was also observed in "BRCAness" ovarian tumors, and in BRCA-related tumors other than ovarian, suggesting that these agents may be active regardless of BRCA mutation status or site of origin. This review aims to describe the principal evidence that led to the development and the study of PARP inhibitors and to discuss their main implications in our daily clinical practice.

Nanoparticle albumin bound Paclitaxel in the treatment of human cancer: nanodelivery reaches prime-time?

Nanoparticle albumin bound paclitaxel (nab-paclitaxel) represents the first nanotechnology-based drug in cancer treatment. We discuss the development of this innovative compound and report the recent changing-practice results in breast and pancreatic cancer. A ground-breaking finding is the demonstration that nab-paclitaxel can not only enhance the activity and reduce the toxicity of chromophore-diluted compound, but also exert activity in diseases considered refractory to taxane-based treatment. This is the first clinical demonstration of major activity of nanotechnologically modified drugs in the treatment of human neoplasms.

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

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.

Loss of BRCA1 function increases the antitumor activity of cisplatin against human breast cancer xenografts in vivo.

BACKGROUND: Previous reports suggested a central role of BRCA1 in DNA-damage repair mechanisms elicited by cell exposure to anti-tumor agents. Here we studied if BRCA1-defective HCC1937 or BRCA1-reconstituted HCC1937/(WT)BRCA1 human breast cancer xenografts (HBCXs) generated in SCID mice were differentially sensitive to cisplatin (CDDP) in vivo and we investigated potential molecular correlates of this effect. RESULTS: CDDP induced almost complete growth inhibition of BRCA1-defective HBCXs, while BRCA1-reconstituted HBCXs were only partially inhibited. Cell cycle analysis showed a significant S- and G(2)/M blockade in BRCA1-defective as compared with parental BRCA1-reconstituted cells. Comparative gene expression profiling of HCC1937 and HCC1937/(WT)BRCA1 showed upregulation of RAD52 and XRCC4, whereas ERCC1 and RRM1 were downregulated. Pathway finder analysis of gene arrays data indicated perturbations of major proliferation and survival pathways suggesting that BRCA1 is mostly involved in G(2)/M but also in G(1)/S-phase checkpoints as well as in several important signaling pathways, including IGF, VEGF, estrogen receptor, PI3K/AKT and EGF. METHODS: HCC1937 or HCC1937/(WT)BRCA1 HBCXs were generated in SCID mice. Animals were then weekly treated with 5 mg/kg CDDP i.p. or with vehicle for 4 w. Tumor volume and mice survival were evaluated. Tumors were retrieved from animals 12 hours after the last treatment with CDDP or vehicle treatment and the cell suspension underwent cell cycle analysis. Differential gene expression and pathway modulation between HCC1937 and HCC1937/(WT)BRCA1 cells were also studied. CONCLUSION: Our data suggest that BRCA1-defective in vivo HBCXs express a molecular scenario predictive of high sensitivity to platinum-derived compounds strongly supporting the rationale for prospective tailored clinical trials in hereditary breast cancer.