Olaparib for adjuvant treatment of BRCA mutation-positive HER2-negative high-risk early breast cancer after chemotherapy

People with BRCA mutation-positive HER2­negative high-risk early breast cancer usually have chemotherapy followed by surgery (neoadjuvant chemotherapy), or surgery followed by chemotherapy (adjuvant chemotherapy). Clinical trial evidence shows that, compared with placebo, olaparib after neoadjuvant or adjuvant chemotherapy decreases the chance of the cancer returning or getting worse, and increases the length of time people live. The cost-effectiveness estimates for olaparib are within what NICE considers to be an acceptable use of NHS resources. So, olaparib is recommended.

Modulation of Early Mitotic Inhibitor 1 (EMI1) depletion on the sensitivity of PARP inhibitors in BRCA1 mutated triple-negative breast cancer cells.

Triple negative breast cancer (TNBC) represents approximately 10-15% of all breast cancers and has a poor outcome as it lacks a receptor target for therapy, and TNBC is frequently associated with a germline mutation of BRCA1. Poly (ADP-ribose) polymerase inhibitor (PARPi) drugs have demonstrated some effectiveness in treating BRCA1 or BRCA2 mutated breast and ovarian cancers but resistance to PARPi is common. Published results found that resistance to Olaparib, a PARPi, can be due to downregulation of EMI1 and the consequent upregulation of the RAD51 recombinase. Using a tissue culture-based cell viability assay, we extended those observations to another PARPi and to other chemotherapy drugs that affect DNA repair or the cell cycle. As we expected, EMI1 downregulation resulted in resistance to another PARPi drug, Talazoparib. EMI1 downregulation also led to resistance to other cytotoxic drugs, Cisplatin and CHK1 inhibitor. Notably, increasing the RAD51 protein expression only recapitulated some, but not all, of the effects of EMI1 depletion in conferring to the cell resistance to different PARPi and the other cytotoxic drugs. These results suggest that the downstream effects of EMI1 downregulation that contribute to PARPi resistance are increasing the concentration of RAD51 protein in the cell and blocking mitotic entry. We found that combining CHK1 inhibitor with olaparib results in restoration of sensitivity even when EMI1 expression is downregulated. This combination therapy may be a means to overcome the PARPi resistance in BRCA1-deficient TNBC cells.

The role of PARP inhibitors in germline BRCA-associated pancreatic ductal adenocarcinoma.

Pancreatic ductal adenocarcinoma (PDAC) is an aggressive malignancy that remains a challenge to treat. In pursuit of personalized medicine, researchers continue active exploration of the genetic and molecular framework of PDAC to apply novel therapeutics and enhance outcomes. In patients who have PDAC, germline mutations-such as those in the BRCA1/2 and PALB2 genes-are predominantly associated with the DNA damage response and repair pathway. On the basis of studies completed in patients with BRCA-mutated advanced breast and ovarian cancer, the poly(ADP-ribose) polymerase (PARP) inhibitors have been evaluated for safety, tolerability, and efficacy in patients with advanced PDAC who are carrying germline BRCA gene mutations. Results have demonstrated meaningful activity and identified BRCA as a predictive and targetable biomarker in PDAC, and have also identified the role of olaparib as a maintenance therapy in PDAC. On the basis of the principle of synthetic lethality, and to avert resistance to PARP inhibitors, clinical trials of combination therapy with PARP inhibitors and platinum-based chemotherapy have been conducted with an early signal. As we continue to explore the role of PARP inhibitors in the management of PDAC, recent clinical trials are studying the effectiveness of PARP inhibitors in combination with immunotherapy, targeted inhibitors, and angiogenesis inhibitors. The next steps are to understand the role of PARP inhibitors beyond germline BRCA in other homologous recombination repair gene mutations and in other subgroups of patients with PDAC.

Polyclonal BRCA2 mutations following carboplatin treatment confer resistance to the PARP inhibitor rucaparib in a patient with mCRPC: a case report.

BACKGROUND: Poly (ADP-ribose) polymerase (PARP) inhibitors are approved for the treatment of breast cancer susceptibility genes 1 and 2 (BRCA1/2) mutant ovarian and breast cancers, and are now being evaluated in metastatic castration-resistant prostate cancer (mCRPC). Reversion mutations that restore BRCA1/2 function have been shown to be responsible for resistance to platinum-based chemotherapy and PARP inhibitors, however there is no information on the sequential use of these agents in prostate cancer. CASE PRESENTATION: A patient with mCRPC associated with a germline BRCA2 mutation was sequentially treated with carboplatin and the PARP inhibitor rucaparib. Genomic profiling of the available baseline tumor and progression blood samples using next-generation sequencing panel tests identified polyclonal BRCA2 reversion mutations post carboplatin treatment but prior to rucaparib treatment. A total of 12 somatic reversion mutations were detected and ranged from small indels to larger deletions of up to 387 amino acids. These alterations are all predicted to restore the BRCA2 open reading frame and potentially protein function. The patient received limited benefit while on rucaparib, likely due to these reversion mutations observed prior to treatment. CONCLUSIONS: Here we report a case of a patient with prostate cancer who received a platinum agent and PARP inhibitor sequentially and in whom polyclonal BRCA2 reversion mutations were identified as the likely mechanism of acquired resistance to carboplatin and primary resistance to PARP inhibition. These findings suggest caution is warranted in sequencing these agents.

A male germ cell assay and supporting somatic cells: its application for the detection of phase specificity of genotoxins in vitro.

Male germ stem cells are responsible for transmission of genetic information to the next generation. Some chemicals exert a negative impact on male germ cells, either directly, or indirectly affecting them through their action on somatic cells. Ultimately, these effects might inhibit fertility, and may exhibit negative consequences on future offspring. Genotoxic anticancer agents may interact with DNA in germ cells potentially leading to a heritable germline mutation. Experimental information in support of this theory has not always been reproducible and suitable in vivo studies remain limited. Thus, alternative male germ cell tests, which are now able to detect phase specificity of such agents, might be used by regulatory agencies to help evaluate the potential risk of mutation. However, there is an urgent need for such approaches for identification of male reproductive genotoxins since this area has until recently been dependent on in vivo studies. Many factors drive alternative approaches, including the (1) commitment to the principles of the 3R's (Replacement, Reduction, and Refinement), (2) time-consuming nature and high cost of animal experiments, and (3) new opportunities presented by new molecular analytical assays. There is as yet currently no apparent appropriate model of full mammalian spermatogenesis in vitro, under the REACH initiative, where new tests introduced to assess genotoxicity and mutagenicity need to avoid unnecessary testing on animals. Accordingly, a battery of tests used in conjunction with the high throughput STAPUT gravity sedimentation was recently developed for purification of male germ cells to investigate genotoxicity for phase specificity in germ cells. This system might be valuable for the examination of phases previously only available in mammals with large-scale studies of germ cell genotoxicity in vivo. The aim of this review was to focus on this alternative approach and its applications as well as on chemicals of known in vivo phase specificities used during this test system development.

Germline variants and response to systemic therapy in advanced prostate cancer.

Our current understanding of prostate cancer pharmacogenomics is growing at a rapid pace. Apart from evaluating relevant biomarkers and genomic alterations in tumor tissues, an increasing focus is being placed on decoding the impact of germline alterations on prostate cancer and its treatment. Herein we summarize various germline variants that have shown to associate with response to systemic therapy in men with advanced prostate cancer. Covered biomarkers include HSD3B1, SLCO2B1, SULT1E1, TRMT11, CYP17A1, CYP1B1, genes involved in homologous recombination and DNA mismatch repair.

DNA Copy Number Variations as Markers of Mutagenic Impact.

DNA copy number variation (CNV) occurs due to deletion or duplication of DNA segments resulting in a different number of copies of a specific DNA-stretch on homologous chromosomes. Implications of CNVs in evolution and development of different diseases have been demonstrated although contribution of environmental factors, such as mutagens, in the origin of CNVs, is poorly understood. In this review, we summarize current knowledge about mutagen-induced CNVs in human, animal and plant cells. Differences in CNV frequencies induced by radiation and chemical mutagens, distribution of CNVs in the genome, as well as adaptive effects in plants, are discussed. Currently available information concerning impact of mutagens in induction of CNVs in germ cells is presented. Moreover, the potential of CNVs as a new endpoint in mutagenicity test-systems is discussed.

Genetic predisposition for malignant mesothelioma: A concise review.

Malignant mesothelioma (MM) is an aggressive cancer associated with asbestos exposure. Studies of familial malignant pleural mesothelioma (MPM) have suggested the existence of a genetic predisposition. Information on the role of genetic risk factors in the development of MM has been growing in the last years, and both low- and high-risk genetic factors have been identified, but genetic factors alone (without any exposure to asbestos or other mineral fibers) have never been shown to induce MM. Low-risk genetic factors have been identified in studies that systematically analyzed the whole genome. When considered alone these low-risk genetic factors carry a relative risk of MPM that is 10- to 15-fold lower than that carried by asbestos exposure; however, a large number of these factors in combination may increase the impact of asbestos exposure. High-risk genetic factors include truncating variants in the tumor suppressor BAP1 and in other tumor suppressor genes belonging to DNA repair pathways. Heterozygous germline variants in these genes may favor carcinogenesis if a second somatic variant occurs that impairs the wild-type allele. This impairment can cause genetic instability due to the suppression of a specific DNA repair pathway, and transformation. This genetic predisposition may have translational consequences, as it may predict patient response to drugs that induce tumor-specific synthetic lethality.

An insight into the genotoxicity assessment studies in dipterans.

The dipterans have been widely utilized in genotoxicity assessment studies. Short life span, easy maintenance, production of large number of offspring in a single generation and the tissues with appropriate cell populations make these flies ideal for studies associated to developmental biology, diseases, genetics, genetic toxicology and stress biology in the group. Moreover, their cosmopolitan presence makes them suitable candidate for ecological bio-monitoring. An attempt has been made in the present review to reveal the significance of dipteran flies for assessing alterations in genetic content through various genotoxicity biomarkers and to summarize the gradual advancement in these studies. Recent studies on genotoxicity assays in dipterans have opened up a broader perspective for DNA repair related mechanistic studies, pre-screening of chemicals and environmental bio-monitoring. Studies in dipterans, other than Drosophila may be helpful in using them as an alternative model system for assessment of genotoxicity, especially at the gene level and further extension of these studies give a future insight to develop new strategies for maintaining environment friendly limits of the toxicants.

Randomized Controlled Trials in Hereditary Cancer Syndromes.

Conducting randomized controlled trials (RCTs) in patients with germline mutations in genes that predispose to adult-onset cancer is hampered by the rarity of these mutations, barriers to their identification, and challenges inherent to randomizing high-risk individuals as part of a clinical trial. Most of the clinically relevant RCTs have been conducted in 3 syndromes in only some of the high-risk genes for which clinical testing is currently available. This article reviews the surgical, screening, and chemoprevention RCTs in each of the syndromes in clinically relevant studies conducted in the past 10 years.

Attainment of a Long-term Favorable Outcome by Sunitinib Treatment for Pancreatic Neuroendocrine Tumor and Renal Cell Carcinoma Associated with von Hippel-Lindau Disease.

von Hippel-Lindau (VHL) disease, caused by germline mutations in the VHL gene, is a hereditary autosomal-dominant disorder which predisposes the individual to various malignant and benign tumors. VHL acts as a tumor suppressor, mainly through the negative regulation of hypoxia-inducible factors. Molecular-targeted drugs against vascular endothelial growth factor-signaling pathways, a target of hypoxia-inducible factors, have recently been introduced into clinical practice for the treatment of patients with sporadic renal cell carcinoma and pancreatic neuroendocrine tumors. However, whether such treatments are effective in patients with VHL disease remains to be elucidated. We herein report a Japanese patient with VHL disease who was successfully treated with sunitinib for approximately 5 years.

Predictive biomarker candidates to delineate efficacy of antiangiogenic treatment in renal cell carcinoma.

Antiangiogenic therapy is currently considered as the cornerstone of treatment in metastatic kidney cancer. A monoclonal antibody against the vascular endothelial growth factor (VEGF) and several tyrosine kinase inhibitors targeting the VEGF receptors demonstrated, 7 years ago, to deeply impact the outcome of this tumor and became a model of integration of molecular knowledge into clinical practice. Unfortunately, no further improvement in survival has been made and 20-25 % of cases remain primary refractory to these drugs, with an overall dismal prognosis. Since biomarker predictors of activity are lacking, their development could highly help in the process of making clinical decisions when choosing the best option for every patient or prompting the inclusion in clinical trials. This unmet medical need could become even more relevant if new immunotherapy confirms its initial promising results in this pathology. In this article, we provide an insight of current state of the art regarding the prediction of antiangiogenic efficacy in kidney cancer and propose new strategies for the implementation of such markers in clinical practice.

Familial and multiple gastrointestinal stromal tumors with fair response to a half-dose of imatinib.

Gastrointestinal stromal tumors (GISTs) are the most common mesenchymal tumors of the gastrointestinal tract. Since our first report in 1998, approximately 30 families with multiple GISTs due to a germline gain-of-function mutation of c-kit have been reported. We herein present a case of a family with multiple GISTs that have a germline c-kit mutation in exon 11 (Del-Val560) in two siblings. One of the patients showed a fair response to treatment with a half-dose of imatinib (200 mg/day). There are few reports describing the response to imatinib in familial GISTs and this drug appears to be a promising therapeutic option.

8-oxoguanine causes spontaneous de novo germline mutations in mice.

Spontaneous germline mutations generate genetic diversity in populations of sexually reproductive organisms, and are thus regarded as a driving force of evolution. However, the cause and mechanism remain unclear. 8-oxoguanine (8-oxoG) is a candidate molecule that causes germline mutations, because it makes DNA more prone to mutation and is constantly generated by reactive oxygen species in vivo. We show here that endogenous 8-oxoG caused de novo spontaneous and heritable G to T mutations in mice, which occurred at different stages in the germ cell lineage and were distributed throughout the chromosomes. Using exome analyses covering 40.9 Mb of mouse transcribed regions, we found increased frequencies of G to T mutations at a rate of 2 × 10(-7) mutations/base/generation in offspring of Mth1/Ogg1/Mutyh triple knockout (TOY-KO) mice, which accumulate 8-oxoG in the nuclear DNA of gonadal cells. The roles of MTH1, OGG1, and MUTYH are specific for the prevention of 8-oxoG-induced mutation, and 99% of the mutations observed in TOY-KO mice were G to T transversions caused by 8-oxoG; therefore, we concluded that 8-oxoG is a causative molecule for spontaneous and inheritable mutations of the germ lineage cells.

Genome-wide ENU mutagenesis in combination with high density SNP analysis and exome sequencing provides rapid identification of novel mouse models of developmental disease.

BACKGROUND: Mice harbouring gene mutations that cause phenotypic abnormalities during organogenesis are invaluable tools for linking gene function to normal development and human disorders. To generate mouse models harbouring novel alleles that are involved in organogenesis we conducted a phenotype-driven, genome-wide mutagenesis screen in mice using the mutagen N-ethyl-N-nitrosourea (ENU). METHODOLOGY/PRINCIPAL FINDINGS: ENU was injected into male C57BL/6 mice and the mutations transmitted through the germ-line. ENU-induced mutations were bred to homozygosity and G3 embryos screened at embryonic day (E) 13.5 and E18.5 for abnormalities in limb and craniofacial structures, skin, blood, vasculature, lungs, gut, kidneys, ureters and gonads. From 52 pedigrees screened 15 were detected with anomalies in one or more of the structures/organs screened. Using single nucleotide polymorphism (SNP)-based linkage analysis in conjunction with candidate gene or next-generation sequencing (NGS) we identified novel recessive alleles for Fras1, Ift140 and Lig1. CONCLUSIONS/SIGNIFICANCE: In this study we have generated mouse models in which the anomalies closely mimic those seen in human disorders. The association between novel mutant alleles and phenotypes will lead to a better understanding of gene function in normal development and establish how their dysfunction causes human anomalies and disease.

NanoTIO(2) (UV-Titan) does not induce ESTR mutations in the germline of prenatally exposed female mice.

BACKGROUND: Particulate air pollution has been linked to an increased risk of cardiovascular disease and cancer. Animal studies have shown that inhalation of air particulates induces mutations in the male germline. Expanded simple tandem repeat (ESTR) loci in mice are sensitive markers of mutagenic effects on male germ cells resulting from environmental exposures; however, female germ cells have received little attention. Oocytes may be vulnerable during stages of active cell division (e.g., during fetal development). Accordingly, an increase in germline ESTR mutations in female mice prenatally exposed to radiation has previously been reported. Here we investigate the effects of nanoparticles on the female germline. Since pulmonary exposure to nanosized titanium dioxide (nanoTiO(2)) produces a long-lasting inflammatory response in mice, it was chosen for the present study. FINDINGS: Pregnant C57BL/6 mice were exposed by whole-body inhalation to the nanoTiO(2) UV-Titan L181 (~42.4 mg UV-Titan/m(3)) or filtered clean air on gestation days (GD) 8-18. Female C57BL/6 F1 offspring were raised to maturity and mated with unexposed CBA males. The F2 descendents were collected and ESTR germline mutation rates in this generation were estimated from full pedigrees (mother, father, offspring) of F1 female mice (192 UV-Titan-exposed F2 offspring and 164 F2 controls). ESTR mutation rates of 0.029 (maternal allele) and 0.047 (paternal allele) in UV-Titan-exposed F2 offspring were not statistically different from those of F2 controls: 0.037 (maternal allele) and 0.061 (paternal allele). CONCLUSIONS: We found no evidence for increased ESTR mutation rates in F1 females exposed in utero to UV-Titan nanoparticles from GD8-18 relative to control females.

Exposure to anticancer drugs can result in transgenerational genomic instability in mice.

The genetic effects of human exposure to anticancer drugs remain poorly understood. To establish whether exposure to anticancer drugs can result not only in mutation induction in the germ line of treated animals, but also in altered mutation rates in their offspring, we evaluated mutation rates in the offspring of male mice treated with three commonly used chemotherapeutic agents: cyclophosphamide, mitomycin C, and procarbazine. The doses of paternal exposure were approximately equivalent to those used clinically. Using single-molecule PCR, the frequency of mutation at the mouse expanded simple tandem repeat locus Ms6-hm was established in DNA samples extracted from sperm and bone marrow of the offspring of treated males. After paternal exposure to any one of these three drugs, expanded simple tandem repeat mutation frequencies were significantly elevated in the germ line (sperm) and bone marrow of their offspring. This observed transgenerational instability was attributed to elevated mutation rates at the alleles derived from both the exposed fathers and from the nonexposed mothers, thus implying a genome-wide destabilization. Our results suggest that paternal exposure to a wide variety of mutagens can result in transgenerational instability manifesting in their offspring. Our data also raise important issues concerning delayed transgenerational effects in the children of survivors of anticancer therapy.