The safety and efficacy of olaparib therapy in patients with relapsed ovarian cancer

Secondary cytoreductive surgery followed by olaparib tablets as maintenance therapy in patients with BRCA mutated recurrent ovarian cancer: A multi-center retrospective study

OBJECTIVE

To evaluate the effect of secondary cytoreductive surgery (SeCRS) followed by platinum-based chemotherapy (PBC) and olaparib tablets as maintenance therapy in patients with BRCA mutated recurrent epithelial ovarian cancer.

METHODS

This was a retrospective study of a prospective database. We collected information on 623 patients diagnosed with BRCA mutated recurrent epithelial ovarian cancer, all of whom underwent SeCRS followed by PBC in combination with or without olaparib. Overall survival and progression-free survival were measured to evaluate treatment effectiveness.

RESULTS

Of the 623 patients recruited, 240 underwent SeCRS plus hyperthermic intraperitoneal chemotherapy followed by PBC and olaparib maintenance therapy (Group A), 248 underwent SeCRS followed by PBC and olaparib maintenance therapy (Group B), and 135 underwent SeCRS followed by PBC only upon recurrence (Group C). The median progression-free survival for Group A was significantly longer than that for Group B (32.5 vs. 24.2 months, P<0.001), and Group B was significantly longer than Group C (24.2 vs. 15.1 months, P<0.001). The median overall survival for Groups A was significantly longer than that for Group B (71.4 vs. 63.5 months, P<0.001), and Group B was significantly longer than Group C (63.5 vs. 47.5 months, P<0.001).

CONCLUSIONS

This study suggested that SeCRS followed by PBC and olaparib maintenance therapy resulted in longer overall survival and progression-free survival than SeCRS followed by PBC only in patients with BRCA mutated recurrent ovarian cancer, especially in patients treated with SeCRS plus hyperthermic intraperitoneal chemotherapy.

Hypoxia-activated prodrugs of phenolic olaparib analogues for tumour-selective chemosensitisation

Poly(ADP-ribose)polymerase inhibitors (PARPi) are used for treatment of tumours with a defect in homologous recombination (HR) repair. Combination with radio- or chemotherapy could broaden their applicability but a major hurdle is enhancement of normal tissue toxicity. Development of hypoxia-activated prodrugs (HAPs) of PARPi has potential to restrict PARP inhibition to tumours thereby avoiding off-target toxicity. We have designed and synthesised phenolic derivatives of olaparib (termed phenolaparibs) and corresponding ether-linked HAPs. Phenolaparib cytotoxicity in HR-proficient and deficient cell lines was consistent with inhibition of PARP-1. Prodrugs were deactivated relative to phenolaparibs in biochemical PARP-1 inhibition assays, and cell culture. Prodrug 7 was selectively converted to phenolaparib 4 under hypoxia and demonstrated hypoxia-selective cytotoxicity, including chemosensitisation of HR-proficient cells in combination with temozolomide. This work demonstrates the feasibility of a HAP approach to PARPi for use in combination therapies.

Studies Towards Hypoxia-Activated Prodrugs of PARP Inhibitors

Poly(ADP-ribose)polymerase (PARP) inhibitors (PARPi) have recently been approved for the treatment of breast and ovarian tumors with defects in homologous recombination repair (HRR). Although it has been demonstrated that PARPi also sensitize HRR competent tumors to cytotoxic chemotherapies or radiotherapy, normal cell toxicity has remained an obstacle to their use in this context. Hypoxia-activated prodrugs (HAPs) provide a means to limit exposure of normal cells to active drug, thus adding a layer of tumor selectivity. We have investigated potential HAPs of model PARPi in which we attach a bioreducible “trigger” to the amide nitrogen, thereby blocking key binding interactions. A representative example showed promise in abrogating PARPi enzymatic activity in a biochemical assay, with a ca. 160-fold higher potency of benzyl phthalazinone 4 than the corresponding model HAP 5, but these N-alkylated compounds did not release the PARPi upon one-electron reduction by radiolysis. Therefore, we extended our investigation to include NU1025, a PARPi that contains a phenol distal to the core binding motif. The resulting 2-nitroimidazolyl ether provided modest abrogation of PARPi activity with a ca. seven-fold decrease in potency, but released the PARPi efficiently upon reduction. This investigation of potential prodrug approaches for PARPi has identified a useful prodrug strategy for future exploration.

Sequential therapeutic targeting of ovarian Cancer harboring dysfunctional BRCA1

Background

Poly (ADP-ribose) polymerase inhibitors (PARPi) have become the first targeted therapies available in the treatment of patients with high-grade serous ovarian cancer (HGSOC). We recently described a significant reduction in PARP1 protein levels in vitro and in vivo in patients treated with standard carboplatinum-paclitaxel chemotherapy, raising the question whether the sequence of treatment used today with chemotherapy followed by PARPi is optimal. In this study, we aim to evaluate if the sequence of PARPi followed by chemotherapy could be more beneficial.

Methods

BRCA1-mutated (UWB1.287, SNU-251), epigenetically-silenced (OVCAR8), and wild-type (SKOV3, A2780PAR & A2780CR) ovarian cancer cell lines were exposed to clinically relevant doses of PARPi followed by different doses of standard chemotherapy and compared to the inverse treatment. The therapeutic efficacy was assessed using colony formation assays. Flow cytometry was used to evaluate cell apoptosis rate and the changes in cell cycle. Finally, apoptotic and cell cycle protein expression was immunodetected using western blot.

Results

Exposure to PARPi prior to standard chemotherapy sensitized BRCA1-mutated or epigenetically-silenced BRCA1 cell lines to lower doses of chemotherapy. Similar results were observed in BRCA1 wild-type and cell lines in which BRCA1 functionality was restored. Moreover, this treatment increased the apoptotic rate in these cell lines.

Conclusion

Pre-treatment with PARPi followed by standard chemotherapy in vitro is more efficient in growth inhibition and induction of apoptosis compared to the administration of standard chemotherapy followed by PARPi.

Electronic supplementary material

The online version of this article (10.1186/s12885-018-5250-4) contains supplementary material, which is available to authorized users.

Guidelines for reporting secondary findings of genome sequencing in cancer genes: the SFMPP recommendations

In oncology, the expanding use of multi-gene panels to explore familial cancer predisposition and tumor genome analysis has led to increased secondary findings discoveries (SFs) and has given rise to important medical, ethical, and legal issues. The American College of Medical Genetics and Genomics published a policy statement for managing SFs for a list of genes, including 25 cancer-related genes. Currently, there are few recommendations in Europe. From June 2016 to May 2017, the French Society of Predictive and Personalized Medicine (SFMPP) established a working group of 47 experts to elaborate guidelines for managing information given on the SFs for genes related to cancers. A subgroup of ethicists, lawyers, patients' representatives, and psychologists provided ethical reflection, information guidelines, and materials (written consent form and video). A subgroup with medical expertise, including oncologists and clinical and molecular geneticists, provided independent evaluation and classification of 60 genes. The main criteria were the "actionability" of the genes (available screening or prevention strategies), the risk evaluation (severity, penetrance, and age of disease onset), and the level of evidence from published data. Genes were divided into three classes: for class 1 genes (n = 36), delivering the information on SFs was recommended; for class 2 genes (n = 5), delivering the information remained questionable because of insufficient data from the literature and/or level of evidence; and for class 3 genes (n = 19), delivering the information on SFs was not recommended. These guidelines for managing SFs for cancer-predisposing genes provide new insights for clinicians and laboratories to standardize clinical practices.

Targeting NAD+ in Metabolic Disease: New Insights Into an Old Molecule

Nicotinamide adenine dinucleotide (NAD+) is an established cofactor for enzymes serving cellular metabolic reactions. More recent research identified NAD+ as a signaling molecule and substrate for sirtuins and poly-adenosine 5'-diphosphate polymerases; enzymes that regulate protein deacetylation and DNA repair, and translate changes in energy status into metabolic adaptations. Deranged NAD+ homeostasis and concurrent alterations in mitochondrial function are intrinsic in metabolic disorders, such as type 2 diabetes, nonalcoholic fatty liver, and age-related diseases. Contemporary NAD+ precursors show promise as nutraceuticals to restore target tissue NAD+ and have demonstrated the ability to improve mitochondrial function and sirtuin-dependent signaling. This review discusses the accumulating evidence for targeting NAD+ metabolism in metabolic disease, maps the different strategies for NAD+ boosting, and addresses the challenges and open questions in the field. The health potential of targeting NAD+ homeostasis will inform clinical study design to identify nutraceutical approaches for combating metabolic disease and the unwanted effects of aging.