PI3K/AKT/mTOR inhibitors in patients with breast and gynecologic malignancies harboring PIK3CA mutations

Phase I/II study of everolimus combined with mFOLFOX-6 and bevacizumab for first-line treatment of metastatic colorectal cancer

Background This phase I/II trial evaluated toxicity and antitumor activity of everolimus plus mFOLFOX6 + bevacizumab for first-line treatment of metastatic colorectal cancer (mCRC). Methods A phase I, modified 3 + 3 Fibonacci schema determined the maximum tolerated dose (MTD) of everolimus, followed by phase II dose expansion. The phase II primary objective was progression-free survival at 6 months (PFS-6 m). Results The everolimus MTD was 10 mg daily with mFOLFOX6 + bevacizumab based on safety from phase I (n = 22). Twenty-five patients were treated in the phase II at 10 mg everolimus daily. Frequent grade 3-4 adverse events were neutropenia (64%), leukopenia (28%) and hypokalemia (26%). Grade 2 stomatitis was observed in 62% of patients. Two dose-limiting toxicities were observed with one attributed to everolimus 10 mg daily (grade 3 diarrhea, hypokalemia, and anorexia) and grade 3 coronary vasospasm attributed to fluorouracil. The objective response rate was 53% and was higher (86%) in those with PTEN deficiency. PFS-6 m was 96% (95% CI 89-99.9%) at the MTD (n = 35). The everolimus recommended phase II dose of this regimen is 7.5 mg daily due to frequent stomatitis and dose reductions. Conclusions Everolimus plus mFOLFOX-6 + bevacizumab is tolerable and demonstrated preliminary efficacy for first-line mCRC. Further studies are warranted in PTEN deficiency.

Comprehensive Genomic Profiling of Hodgkin Lymphoma Reveals Recurrently Mutated Genes and Increased Mutation Burden

A better understanding of the underlying disease biology that leads to improvement in treatment outcomes is needed. Investigation of the genomic landscape of Hodgkin lymphoma has been difficult because of the low tumor content in these inflammatory cell‐ and stroma‐rich tissue samples. A comprehensive genomic profiling with targeted next‐generation sequencing panel was performed to test for genomic aberrations in archival tumor samples from patients with Hodgkin lymphoma to identify potentially actionable molecular targets.

Background.

The genomic landscape of Hodgkin lymphoma (HL) has been difficult to characterize due to the paucity of neoplastic cells and an abundant microenvironment. Such characterization is needed in order to improve treatment strategies.

Materials and Methods.

We performed comprehensive genomic profiling (CGP) using targeted next‐generation sequencing on archival formalin‐fixed paraffin embedded tumor samples from 63 patients to analyze the landscape of HL.

Results.

CGP was successful for 49/63 archival specimens (78%), and revealed aberrations impacting genes including B2M, TP53, and XPO1 (E571). Of the 34 patients for whom total mutation burden (TMB; mutations/megabase [Mb]) was assessed, 5 (15%) had high TMB (≥20 mutations/Mb), 18 (53%) had intermediate TMB (6–19 mutations/Mb), and 11 (32%) had low TMB (≤5 mutations/Mb). We next tested 13 patients' plasma cell‐free DNA with droplet digital polymerase chain reaction for the presence of XPO1 E571 mutation, which was confirmed in the plasma of 31% of patients. In three patients with serially collected plasma samples, XPO1 E571K allelic frequency changes corresponded with changes in tumor size on conventional radiographic imaging.

Conclusion.

The study demonstrates that comprehensive genomic profiling of archival Hodgkin lymphoma tumor samples is feasible and leads to the identification of genes that are recurrently mutated and that Hodgkin lymphoma has increased mutation burden in the majority of samples analyzed. Furthermore, tracking of XPO1 E571 mutant allele frequency in a subset of patients may also represent a potential disease‐monitoring strategy and warrants further investigation.

Implications for Practice.

This study provides the first evidence that comprehensive genomic profiling can be performed to map the genomic landscape of Hodgkin lymphoma and that a subpopulation of patients has mutations in TP53, B2M, XPO1, and other genes. It was found that 15% of patients have high mutation burden, which, in cancers such as melanoma, may indicate sensitivity to immune checkpoint inhibitors, and may thus be explored for Hodgkin lymphoma. Lastly, this work demonstrates that changes in the mutant allele frequency of XPO1 in serially collected plasma cell‐free DNA samples correspond with treatment outcomes measured with conventional radiographic imaging.

PIK3CA mutations are specifically localized to lymphatic endothelial cells of lymphatic malformations

Lymphatic malformations (LM) are characterized by the overgrowth of lymphatic vessels during pre- and postnatal development. Macrocystic, microcystic and combined forms of LM are known. The cysts are lined by lymphatic endothelial cells (LECs). Resection and sclerotherapy are the most common treatment methods. Recent studies performed on LM specimens in the United States of America have identified activating mutations in the phosphatidylinositol-4,5-bisphosphate 3-kinase catalytic subunit alpha (PIK3CA) gene in LM. However, whole tissue but not isolated cell types were studied. Here, we studied LM tissues resected at the University Hospitals Freiburg and Regensburg, Germany. We isolated LECs and fibroblasts separately, and sequenced the commonly affected exons 8, 10, and 21 of the PIK3CA gene. We confirm typical monoallelic mutations in 4 out of 6 LM-derived LEC lines, and describe two new mutations i.) in exon 10 (c.1636C>A; p.Gln546Lys), and ii.) a 3bp in-frame deletion of GAA (Glu109del). LM-derived fibroblasts did not possess such mutations, showing cell-type specificity of the gene defect. High activity of the PIK3CA—AKT- mTOR pathway was demonstrated by hyperphosphorylation of AKT-Ser473 in all LM-derived LECs (including the ones with newly identified mutations), as compared to normal LECs. Additionally, hyperphosphorylation of ERK was seen in all LM-derived LECs, except for the one with Glu109del. In vitro, the small molecule kinase inhibitors Buparlisib/BKM-120, Wortmannin, and Ly294002, (all inhibitors of PIK3CA), CAL-101 (inhibitor of PIK3CD), MK-2206 (AKT inhibitor), Sorafenib (multiple kinases inhibitor), and rapamycin (mTOR inhibitor) significantly blocked proliferation of LM-derived LECs in a concentration-dependent manner, but also blocked proliferation of normal LECs. However, MK-2206 appeared to be more specific for mutated LECs, except in case of Glu109 deletion. In sum, children that are, or will be, treated with kinase inhibitors must be monitored closely.

20(s)-Protopanaxadiol (PPD) increases the radiotherapy sensitivity of laryngeal carcinoma

Laryngeal carcinoma (LC) is one of the most prevalent malignant tumors in the head and neck area. Due to its high morbidity and mortality, LC poses a serious threat to human life and health. Even with surgical removal, some patients were not sensitive to radiotherapy or experienced transfer or recurrence. 20(s)-Protopanaxadiol (PPD), a natural product from Panax ginseng, has been reported to have cytotoxic effects against several cancer cell lines. However, whether it can improve the radiation sensitivity and the underlying mechanism of PPD's sensitization effect is still unknown. Herein, from in vitro and in vivo experiments, we found that the combination of PPD and radiation not only significantly inhibited proliferation and induced apoptosis, but also suppressed the tumor growth in mouse models. These findings confirmed the role of PPD in enhancing the sensitivity of radiotherapy. Moreover, our work showed that the expression levels of mTOR and its downstream effectors decreased remarkably after PPD addition when compared to radiation only. This result suggested that PPD's excellent synergistic effects with radiation might be associated with the down-regulation of the mTOR signaling pathway in Hep-2 cells.

Conception and Management of a Poorly Understood Spectrum of Dermatologic Neoplasms: Atypical Fibroxanthoma, Pleomorphic Dermal Sarcoma, and Undifferentiated Pleomorphic Sarcoma

OPINION STATEMENT

Atypical fibroxanthoma (AFX) and pleomorphic dermal sarcoma (PDS) tumors share many clinical, etiologic, and histologic features and likely represent components of a tumor spectrum. In dermatologic oncology, differentiating between AFX and PDS is pivotal as tumors with histological features consistent with PDS are more likely to behave in a clinically aggressive manner. Importantly, the term "pleomorphic dermal sarcoma" (PDS) is a more appropriate designation than "undifferentiated pleomorphic sarcoma" (UPS) for describing deeper, more aggressive, histologically high-grade cutaneous tumors that otherwise resemble AFX. Surgery remains the gold standard for treatment. In the setting of AFX, excision with the Mohs micrographic technique appears to offer superior tumor control rates while maintaining greater tissue preservation over wide local excision and should be considered first line. In the setting of PDS, optimal management is less clear given the paucity of available data. However, due to its greater propensity to recur and metastasize, extirpation with complete tumor margin control appears paramount. The roles of imaging and SLNB in management and clinical outcomes of AFX and PDS are unclear given the lack of available data. In reality, these tools are unlikely to be helpful in most cases of AFX. However, in the setting of PDS, emerging literature indicates that these tumors are inherently higher risk, and thus, imaging and SLNB may be helpful in select cases. Additionally, radiation therapy may be of adjuvant benefit for these tumors when clear surgical margins cannot be obtained. While traditional chemotherapy has been largely ineffectual, the recent discovery of key oncogenetic mutations has allowed for the identification of several potential molecular drug targets that may have a therapeutic role with future study. In the unfortunate setting of metastatic disease, a multidisciplinary approach is optimal. Further studies are needed to establish definitive conclusions regarding risk stratification and best management practices.

Effect of CXCR4 silencing with shRNA on MAPK signaling in ovarian cancer

Our previous study demonstrated that short hairpin RNA (shRNA) targeting of C-X-C chemokine receptor type 4 (CXCR4) significantly inhibited cell proliferation, metastasis and invasion. On the basis of these results, the aim of the present study was to determine the effects of shRNA-CXCR4 silencing on mitogen-activated protein kinase (MAPK) signaling in human SW626 ovarian cancer cells. Following silencing the CXCR4 gene with shRNA, the mRNA expression of apoptosis signal-regulating kinase 1 (ASK1) was determined using the reverse transcription-quantitative polymerase chain reaction, whereas the protein expression of extracellular-signal-regulated kinase (ERK)1/2 and phosphorylated (p)-c-Jun were determined using immunocytochemistry and western blotting. SW626 cells transfected with shRNA-CXCR4 exhibited significantly increased ASK1 mRNA expression (P<0.05), significantly increased p-c-Jun protein expression (P<0.05), and significantly decreased ERK1/2 protein expression (P<0.05). Silencing the CXCR4 gene with shRNA significantly inhibited cell proliferation, promoted cell apoptosis and may be mediated by the MAPK signaling pathway.

Translational Genomics: Practical Applications of the Genomic Revolution in Breast Cancer

The genomic revolution has fundamentally changed our perception of breast cancer. It is now apparent from DNA-based massively parallel sequencing data that at the genomic level, every breast cancer is unique and shaped by the mutational processes to which it was exposed during its lifetime. More than 90 breast cancer driver genes have been identified as recurrently mutated, and many occur at low frequency across the breast cancer population. Certain cancer genes are associated with traditionally defined histologic subtypes, but genomic intertumoral heterogeneity exists even between cancers that appear the same under the microscope. Most breast cancers contain subclonal populations, many of which harbor driver alterations, and subclonal structure is typically remodeled over time, across metastasis and as a consequence of treatment interventions. Genomics is deepening our understanding of breast cancer biology, contributing to an accelerated phase of targeted drug development and providing insights into resistance mechanisms. Genomics is also providing tools necessary to deliver personalized cancer medicine, but a number of challenges must still be addressed. Clin Cancer Res; 23(11); 2630-9. ©2017 AACRSee all articles in this CCR Focus section, "Breast Cancer Research: From Base Pairs to Populations."

Targeting the PI3K pathway in cancer: are we making headway?

The PI3K-AKT-mTOR pathway is one of the most frequently dysregulated pathways in cancer and, consequently, more than 40 compounds that target key components of this signalling network have been tested in clinical trials involving patients with a range of different cancers. The clinical development of many of these agents, however, has not advanced to late-phase randomized trials, and the antitumour activity of those that have been evaluated in comparative prospective studies has typically been limited, or toxicities were found to be prohibitive. Nevertheless, the mTOR inhibitors temsirolimus and everolimus and the PI3K inhibitors idelalisib and copanlisib have been approved by the FDA for clinical use in the treatment of a number of different cancers. Novel compounds with greater potency and selectivity, as well as improved therapeutic indices owing to reduced risks of toxicity, are clearly required. In addition, biomarkers that are predictive of a response, such as PIK3CA mutations for inhibitors of the PI3K catalytic subunit α isoform, must be identified and analytically and clinically validated. Finally, considering that oncogenic activation of the PI3K-AKT-mTOR pathway often occurs alongside pro-tumorigenic aberrations in other signalling networks, rational combinations are also needed to optimize the effectiveness of treatment. Herein, we review the current experience with anticancer therapies that target the PI3K-AKT-mTOR pathway.

Clinical implications of genomic profiles in metastatic breast cancer with a focus on TP53 and PIK3CA, the most frequently mutated genes

Breast cancer (BC) has been genetically profiled through large-scale genome analyses. However, the role and clinical implications of genetic alterations in metastatic BC (MBC) have not been evaluated. Therefore, we conducted whole-exome sequencing (WES) and RNA-Seq of 37 MBC samples and targeted deep sequencing of another 29 MBCs. We evaluated somatic mutations from WES and targeted sequencing and assessed gene expression and performed pathway analysis from RNA-Seq. In this analysis, PIK3CA was the most commonly mutated gene in estrogen receptor (ER)-positive BC, while in ER-negative BC, TP53 was the most commonly mutated gene (p = 0.018 and p < 0.001, respectively). TP53 stopgain/loss and frameshift mutation was related to low expression of TP53 in contrast nonsynonymous mutation was related to high expression. The impact of TP53 mutation on clinical outcome varied with regard to ER status. In ER-positive BCs, wild type TP53 had a better prognosis than mutated TP53 (median overall survival (OS) (wild type vs. mutated): 88.5 ± 54.4 vs. 32.6 ± 10.7 (months), p = 0.002). In contrast, mutated TP53 had a protective effect in ER-negative BCs (median OS: 0.10 vs. 32.6 ± 8.2, p = 0.026). However, PIK3CA mutation did not affect patient survival. In gene expression analysis, CALM1, a potential regulator of AKT, was highly expressed in PIK3CA-mutated BCs. In conclusion, mutation of TP53 was associated with expression status and affect clinical outcome according to ER status in MBC. Although mutation of PIK3CA was not related to survival in this study, mutation of PIK3CA altered the expression of other genes and pathways including CALM1 and may be a potential predictive marker of PI3K inhibitor effectiveness.

Kinase-targeted cancer therapies: progress, challenges and future directions

The human genome encodes 538 protein kinases that transfer a γ-phosphate group from ATP to serine, threonine, or tyrosine residues. Many of these kinases are associated with human cancer initiation and progression. The recent development of small-molecule kinase inhibitors for the treatment of diverse types of cancer has proven successful in clinical therapy. Significantly, protein kinases are the second most targeted group of drug targets, after the G-protein-coupled receptors. Since the development of the first protein kinase inhibitor, in the early 1980s, 37 kinase inhibitors have received FDA approval for treatment of malignancies such as breast and lung cancer. Furthermore, about 150 kinase-targeted drugs are in clinical phase trials, and many kinase-specific inhibitors are in the preclinical stage of drug development. Nevertheless, many factors confound the clinical efficacy of these molecules. Specific tumor genetics, tumor microenvironment, drug resistance, and pharmacogenomics determine how useful a compound will be in the treatment of a given cancer. This review provides an overview of kinase-targeted drug discovery and development in relation to oncology and highlights the challenges and future potential for kinase-targeted cancer therapies.

Cross-talk Signaling between HER3 and HPV16 E6 and E7 Mediates Resistance to PI3K Inhibitors in Head and Neck Cancer

Human papillomavirus (HPV) type 16 is implicated in approximately 75% of head and neck squamous cell carcinomas (HNSCC) that arise in the oropharynx, where viral expression of the E6 and E7 oncoproteins promote cellular transformation, tumor growth, and maintenance. An important oncogenic signaling pathway activated by E6 and E7 is the PI3K pathway, a key driver of carcinogenesis. The PI3K pathway is also activated by mutation or amplification of PIK3CA in over half of HPV(+) HNSCC. In this study, we investigated the efficacy of PI3K-targeted therapies in HPV(+) HNSCC preclinical models and report that HPV(+) cell line- and patient-derived xenografts are resistant to PI3K inhibitors due to feedback signaling emanating from E6 and E7. Receptor tyrosine kinase profiling indicated that PI3K inhibition led to elevated expression of the HER3 receptor, which in turn increased the abundance of E6 and E7 to promote PI3K inhibitor resistance. Targeting HER3 with siRNA or the mAb CDX-3379 reduced E6 and E7 abundance and enhanced the efficacy of PI3K-targeted therapies. Together, these findings suggest that cross-talk between HER3 and HPV oncoproteins promotes resistance to PI3K inhibitors and that cotargeting HER3 and PI3K may be an effective therapeutic strategy in HPV(+) tumors.Significance: These findings suggest a new therapeutic combination that may improve outcomes in HPV(+) head and neck cancer patients. Cancer Res; 78(9); 2383-95. ©2018 AACR.

Preclinical evaluation and reverse phase protein Array-based profiling of PI3K and MEK inhibitors in endometrial carcinoma in vitro

BACKGROUND

The phosphoinositide-3-kinase (PI3K) pathway is the most commonly activated pathway in cancers due to mutations at multiple nodes and loss of PTEN. Furthermore, in endometrial cancer (EC), PI3K and RAS/RAF/MEK/MAPK (RAS/MAPK herein) pathway mutations frequently co-exist. We examined the role of PI3K and RAS/MAPK pathway mutations in determining responsiveness to therapies targeted to these pathways in vitro in EC.

METHODS

13 EC cell lines were profiled for their PI3K pathway and KRAS mutational and PTEN protein status and treated with one MEK- and two PI3K- targeted inhibitors alone and in combination. Expression and phosphorylation of 66 proteins were evaluated by Reverse-Phase-Protein-Array (RPPA) in 6 EC cell lines to identify signalling changes in these pathways in response to therapy.

RESULTS

PTEN protein loss and the absence of any tested pathway mutations are dominant negative predictors of sensitivity to MEK inhibition. KRAS-mutated cells were most sensitive to MEK inhibition, but significantly more resistant to PI3K inhibition than KRAS-wild-type cell lines. Combinations of PI3K and MEK inhibitors showed synergy or additivity in all but two cell lines tested. Treatment of KRAS-mutated cells with PI3K inhibitors and treatment of PTEN-low cells with a MEK inhibitor were most likely to induce activation of MEK/MAPK and AKT, respectively, likely indicative of feedback-loop regulation.

CONCLUSIONS

MEK inhibition may be a promising treatment modality, not just for ECs with mutated KRAS, but also for those with retained PTEN. Up-regulation of MEK/MAPK signalling by PI3K inhibition, and up-regulation of AKT activation by MEK inhibition may serve as potential biomarkers of likely responsiveness to each inhibitor.

Selective mTORC2 Inhibitor Therapeutically Blocks Breast Cancer Cell Growth and Survival

Small-molecule inhibitors of the mTORC2 kinase (torkinibs) have shown efficacy in early clinical trials. However, the torkinibs under study also inhibit the other mTOR-containing complex mTORC1. While mTORC1/mTORC2 combined inhibition may be beneficial in cancer cells, recent reports describe compensatory cell survival upon mTORC1 inhibition due to loss of negative feedback on PI3K, increased autophagy, and increased macropinocytosis. Genetic models suggest that selective mTORC2 inhibition would be effective in breast cancers, but the lack of selective small-molecule inhibitors of mTORC2 have precluded testing of this hypothesis to date. Here we report the engineering of a nanoparticle-based RNAi therapeutic that can effectively silence the mTORC2 obligate cofactor Rictor. Nanoparticle-based Rictor ablation in HER2-amplified breast tumors was achieved following intratumoral and intravenous delivery, decreasing Akt phosphorylation and increasing tumor cell killing. Selective mTORC2 inhibition in vivo, combined with the HER2 inhibitor lapatinib, decreased the growth of HER2-amplified breast cancers to a greater extent than either agent alone, suggesting that mTORC2 promotes lapatinib resistance, but is overcome by mTORC2 inhibition. Importantly, selective mTORC2 inhibition was effective in a triple-negative breast cancer (TNBC) model, decreasing Akt phosphorylation and tumor growth, consistent with our findings that RICTOR mRNA correlates with worse outcome in patients with basal-like TNBC. Together, our results offer preclinical validation of a novel RNAi delivery platform for therapeutic gene ablation in breast cancer, and they show that mTORC2-selective targeting is feasible and efficacious in this disease setting.Significance: This study describes a nanomedicine to effectively inhibit the growth regulatory kinase mTORC2 in a preclinical model of breast cancer, targeting an important pathogenic enzyme in that setting that has been undruggable to date. Cancer Res; 78(7); 1845-58. ©2018 AACR.

Biologic Impact and Clinical Implication of mTOR Inhibition in Metastatic Breast Cancer

The goal of therapy for patients with metastatic breast cancer (MBC) is prolonging life and palliation of symptoms. Thus the preferred approach remains to use, at least initially, non-cytotoxic drugs. In hormone receptor-positive breast cancer the sequential use of single anti-estrogen drugs, e.g. tamoxifen, aromatase inhibitors, and many others is standard, but eventually drug resistance will lead to failure of these compounds and a switch to chemotherapy will be necessary. Reversing resistance to anti-estrogen therapy in MBC is one of the strategies to avoid and delay the use of cytotoxic compounds. The mammalian target of rapamycin (mTOR) has been recently associated with in vitro reversal of drug resistance, including tamoxifen resistance. A number of early clinical studies have confirmed the concept and, more recently, everolimus was successfully tested in a randomized controlled trial in postmenopausal patients who progressed on previous anti-estrogen therapy for MBC. This manuscript will review the biology, preclinical and clinical data including the randomized controlled trial that lead to the approval of everolimus by the US FDA.

Brucein D, a Naturally Occurring Tetracyclic Triterpene Quassinoid, Induces Apoptosis in Pancreatic Cancer through ROS-Associated PI3K/Akt Signaling Pathway

Brucein D (BD), a major active quassinoid in Brucea javanica, has exhibited pronounced anticancer activities. However, the biologic mechanisms have not been fully explored. In this study, BD exhibited more potent cytotoxic effect on pancreatic cancer (PanCa) cell lines, while exerted weaker cytotoxic effects on GES-1 cells (non-tumorigenic). BD was shown to elicit apoptosis through inducing both the intrinsic and extrinsic mitochondria-mediated caspase activations. Furthermore, the BD-induced apoptotic effects were dependent on the accumulated reactive oxygen species (ROS) and inactivation of PI3K/Akt signaling pathway. Pretreatment with tempol completely prevented the cellular apoptosis induced by BD, and recovered the inactivation of AKT, which suggested ROS essentially involved in BD-elicited apoptosis and down-regulation of PI3K/Akt pathway. In addition, the results obtained from orthotopic xenograft in nude mice were congruent with those of the in vitro investigations. These results support the notion that BD held good potential to be further developed into an effective pharmaceutical agent for the treatment of PanCa.

Biomarkers of Everolimus Sensitivity in Hormone Receptor-Positive Breast Cancer

Activation of the mammalian target of rapamycin (mTOR) signaling pathway is an important mechanism of resistance to endocrine therapy in breast cancer. Everolimus, an mTOR inhibitor, has been shown to increase the efficacy of endocrine therapy and overcome resistance to endocrine therapies. Clinical studies have suggested that everolimus combined with endocrine therapy prolongs progression-free survival in hormone receptor-positive breast cancer patients. However, because breast cancer includes a group of highly heterogeneous tumors, patients may have different responses to everolimus. Therefore, finding biomarkers that can predict a patient's positive response or resistance to everolimus is critical. Numerous preclinical studies have shown that PIK3CA/PTEN mutations are predictive of sensitivity to everolimus; however, clinical trials have not confirmed the correlation between mutation status and clinical response. KRAS or BRAF mutations can bypass the phosphatidylinositol 3-kinase pathway; therefore, mutations in KRAS or BRAF may lead to resistance to mTOR inhibitors, and preclinical studies have shown that PIK3CA mutant cells which also contain KRAS mutations are resistant to everolimus. However, there are no clinical data in breast cancer patients to support this conclusion. Therefore, large-scale clinical studies are needed to identify biomarkers of efficacy and resistance to everolimus.

Oncogene and therapeutic target analyses in atypical fibroxanthomas and pleomorphic dermal sarcomas

BACKGROUND

Until now, almost nothing is known about the tumorigenesis of atypical fibroxanthoma (AFX) and pleomorphic dermal sarcoma (PDS). Our hypothesis is that AFX is the non-infiltrating precursor lesion of PDS.

MATERIALS AND METHODS

We performed the world-wide most comprehensive immunohistochemical and mutational analysis in well-defined AFX (n=5) and PDS (n=5).

RESULTS

In NGS-based mutation analyses of selected regions by a 17 hotspot gene panel of 102 amplicons we could detect TP53 mutations in all PDS as well as in the only analyzed AFX and PDS of the same patient. Besides, we detected mutations in the CDKN2A, HRAS, KNSTRN and PIK3CA genes.Performing immunohistochemistry for CTNNB1, KIT, CDK4, c-MYC, CTLA-4, CCND1, EGFR, EPCAM, ERBB2, IMP3, INI-1, MKI67, MDM2, MET, p40, TP53, PD-L1 and SOX2 overexpression of TP53, CCND1 and CDK4 was seen in AFX as well as in PDS. IMP3 was upregulated in 2 AFX (weak staining) and 4 PDS (strong staining).FISH analyses for the genes FGFR1, FGFR2 and FGFR3 revealed negative results in all tumors.

CONCLUSIONS

UV-induced TP53 mutations as well as CCND1/CDK4 changes seem to play essential roles in tumorigenesis of PDS. Furthermore, we found some more interesting mutated genes in other oncogene pathways (activating mutations of HRAS and PIK3CA). All AFX and PDS investigated immunohistochemically presented with similar oncogene expression profiles (TP53, CCND1, CDK4 overexpression) and the single case with an AFX and PDS showed complete identical TP53 and PIK3CA mutation profiles in both tumors. This reinforces our hypothesis that AFX is the non-infiltrating precursor lesion of PDS.

YAP1 inhibition radiosensitizes triple negative breast cancer cells by targeting the DNA damage response and cell survival pathways

The Hippo pathway is an evolutionarily conserved signaling pathway that regulates proliferation and apoptosis to control organ size during developmental growth. Yes-associated protein 1 (YAP1), the terminal effector of the Hippo pathway, is a transcriptional co-activator and a potent growth promoter that has emerged as a critical oncogene. Overexpression of YAP1 has been implicated in promoting resistance to chemo-, radiation and targeted therapy in various cancers. However, the role of YAP1 in radioresistance in triple-negative breast cancer (TNBC) is currently unknown. We evaluated the role of YAP1 in radioresistance in TNBC in vitro, using two approaches to inhibit YAP1: 1) genetic inhibition by YAP1 specific shRNA or siRNA, and 2) pharmacological inhibition by using the small molecule inhibitor, verteporfin that prevents YAP1 transcriptional activity. Our findings demonstrate that both genetic and pharmacological inhibition of YAP1 sensitizes TNBC cells to radiation by inhibiting the EGFR/PI3K/AKT signaling axis and causing an increased accumulation of DNA damage. Our results reveal that YAP1 activation exerts a protective role for TNBC cells in radiotherapy and represents a pharmacological target to enhance the anti-tumor effects of DNA damaging modalities in the treatment of TNBC.

Erythropoietin and mTOR: A "One-Two Punch" for Aging-Related Disorders Accompanied by Enhanced Life Expectancy

Life expectancy continues to increase throughout the world, but is accompanied by a rise in the incidence of non-communicable diseases. As a result, the benefits of an increased lifespan can be limited by aging-related disorders that necessitate new directives for the development of effective and safe treatment modalities. With this objective, the mechanistic target of rapamycin (mTOR), a 289-kDa serine/threonine protein, and its related pathways of mTOR Complex 1 (mTORC1), mTOR Complex 2 (mTORC2), proline rich Akt substrate 40 kDa (PRAS40), AMP activated protein kinase (AMPK), Wnt signaling, and silent mating type information regulation 2 homolog 1 (Saccharomyces cerevisiae) (SIRT1), have generated significant excitement for furthering novel therapies applicable to multiple systems of the body. Yet, the biological and clinical outcome of these pathways can be complex especially with oversight of cell death mechanisms that involve apoptosis and autophagy. Growth factors, and in particular erythropoietin (EPO), are one avenue under consideration to implement control over cell death pathways since EPO can offer potential treatment for multiple disease entities and is intimately dependent upon mTOR signaling. In experimental and clinical studies, EPO appears to have significant efficacy in treating several disorders including those involving the developing brain. However, in mature populations that are affected by aging-related disorders, the direction for the use of EPO to treat clinical disease is less clear that may be dependent upon a number of factors including the understanding of mTOR signaling. Continued focus upon the regulatory elements that control EPO and mTOR signaling could generate critical insights for targeting a broad range of clinical maladies.

PIK3CA exon9 mutations associate with reduced survival, and are highly concordant between matching primary tumors and metastases in endometrial cancer

Mutations of the phosphoinositide-3-kinase (PI3K) catalytic subunit alpha gene (PIK3CA) are frequent in endometrial cancer. We sequenced exon9 and exon20 of PIK3CA in 280 primary endometrial cancers to assess the relationship with clinicopathologic variables, patient survival and associations with PIK3CA mRNA and phospho-AKT1 by gene expression and protein data, respectively. While PIK3CA mutations generally had no impact on survival, and were not associated with clinicopathological variables, patients with exon9 charge-changing mutations, providing a positive charge at the substituted amino acid residue, were associated with poor survival (p = 0.018). Furthermore, we characterized PIK3CA mutations in the metastatic setting, including 32 patients with matched primary tumors and metastases, and found a high level of concordance (85.7%; 6 out of 7 patients), suggesting limited heterogeneity. PIK3CA mRNA levels were increased in metastases compared to the primary tumors (p = 0.031), independent of PIK3CA mutation status, which rather associated with reduced PIK3CA mRNA expression. PIK3CA mutated tumors expressed higher p-AKT/AKT protein levels, both within primary (p < 0.001) and metastatic lesion (p = 0.010). Our results support the notion that the PI3K signaling pathway might be activated, both dependent- and independently of PIK3CA mutations, an aspect that should be considered when designing PIK3 pathway targeting strategies in endometrial cancer.

Potential therapeutic targets of triple-negative breast cancer based on its intrinsic subtype

Triple-negative breast cancer (TNBC) is an aggressive subgroup of human breast cancer, which is characterized as estrogen receptor (ER) negative, progesterone receptor (PR) negative, and human epidermal growth factor receptor 2 (HER2) negative. TNBC is the most difficult breast cancer subgroup to treat, due to its unresponsiveness to current clinical targeted therapies, high rate of recurrence, and poor prognosis. Thus, there is an urgent medical need to identify therapeutic targets and develop more effective stratified medicine for the treatment of TNBC. Here we review the potential therapeutic targets for TNBC based on its intrinsic subtype. We also review the aberrant activated signals found in different subgroups of TNBC, including androgen receptor (AR) and PI3K/AKT/mTOR, Notch, Wnt/β-catenin, Hedge-hog, and TGF-β signaling pathways, which play essential roles in multiple development stages of TNBC. The careful analysis of these signaling pathways and therapeutic targets would have significant impact on the drug development and clinical trials, leading to effective therapies for this deadly disease.

Predicting treatment resistance and relapse through circulating DNA

The use of circulating DNA(ctDNA) to provide a non-invasive, personalised genomic snapshot of a patients' tumour has huge potential. Over the past five years this area of research has gained huge momentum. A number of studies in metastatic breast cancer have shown the potential of ctDNA to predict prognosis and treatment response using ctDNA. Further developments have included deeper sequencing using whole exome and shallow whole genome approaches which has the potential to identify new mutations and chromosomal copy number changes which appear upon resistance to treatment. In early breast cancer, recent work utilising personalised digital PCR probes has shown huge potential in predicting disease relapse and the detection of micrometastatic disease which could lead to improved treatment and outcome for these patients. Specific pathways of resistance can also be monitored and liquid biopsy approaches for the detection of ESR1 mutations have been used which could identify patients who have become resistant to particular endocrine therapies. The identification of PIK3CA mutations in plasma has also been shown to predict a higher response rate to specific PI3K inhibitors and could be used as a non-invasive screening tool prior to treatment. Further work on the detection of exosomal miRNA and hypermethylated DNA in plasma have shown promise in terms of specificity for early breast cancer detection and could be used to monitor treatment response. This review will focus on technological advances in the field, early detection of relapse and the detection of tumour-specific genomic alterations which could predict treatment response and resistance in patients with breast cancer.

Target and Agent Prioritization for the Children's Oncology Group-National Cancer Institute Pediatric MATCH Trial

Over the past decades, outcomes for children with cancer have improved dramatically through serial clinical trials based in large measure on dose intensification of cytotoxic chemotherapy for children with high-risk malignancies. Progress made through such dose intensification, in general, is no longer yielding further improvements in outcome. With the revolution in sequencing technologies and rapid development of drugs that block specific proteins and pathways, there is now an opportunity to improve outcomes for pediatric cancer patients through mutation-based targeted therapeutic strategies. The Children's Oncology Group (COG), in partnership with the National Cancer Institute (NCI), is planning a trial entitled the COG-NCI Pediatric Molecular Analysis for Therapeutic Choice (Pediatric MATCH) protocol utilizing an umbrella design. This protocol will have centralized infrastructure and will consist of a biomarker profiling protocol and multiple single-arm phase II trials of targeted therapies. Pediatric patients with recurrent or refractory solid tumors, lymphomas, or histiocytoses with measurable disease will be eligible. The Pediatric MATCH Target and Agent Prioritization (TAP) committee includes membership representing COG disease committees, the Food and Drug Administration, and the NCI. The TAP Committee systematically reviewed target and agent pairs for inclusion in the Pediatric MATCH trial. Fifteen drug-target pairs were reviewed by the TAP Committee, with seven recommended for further development as initial arms of the Pediatric MATCH trial. The current evidence for availability, efficacy, and safety of targeted agents in children for each class of mutation considered for inclusion in the Pediatric MATCH trial is discussed in this review.

Phosphoinositide 3-kinase (PI3K) pathway inhibitors in solid tumors: From laboratory to patients

The phosphoinositide 3-kinase (PI3K) pathway is an intracellular signaling pathway that has regulatory roles in cell survival, proliferation, and differentiation, and a critical role in tumorigenesis. In cancer, multiple studies have investigated the therapeutic targeting of the PI3K pathway, and multiple inhibitors targeting PI3K and its isoforms, protein kinase B/AKT, mammalian target of rapamycin (mTOR), and other pathway proteins have been developed. For the treatment of solid tumors, only allosteric mTOR inhibitors, such as everolimus and temsirolimus, are currently approved for clinical use. This review describes the PI3K inhibitors that have progressed from the laboratory to late-stage clinical trials, and discusses the challenges that have prevented other compounds from doing the same. Challenges to the therapeutic effectiveness of some PI3K inhibitors include the absence of reliable and effective biomarkers, their limited efficacy as single agents, insufficient development of rational therapeutic combinations, the use of schedules with a variety of off-target effects, and suboptimal therapeutic exposures. Therefore, with regard to PI3K inhibitors currently in late-stage clinical trials, the identification of appropriate biomarkers of efficacy and the development of optimal combination regimens and dosing schedules are likely to be important for graduation into clinical practice.

Mutation-Enrichment Next-Generation Sequencing for Quantitative Detection of KRAS Mutations in Urine Cell-Free DNA from Patients with Advanced Cancers

Purpose: Tumor-derived cell-free DNA (cfDNA) from urine of patients with cancer offers noninvasive biological material for detection of cancer-related molecular abnormalities such as mutations in Exon 2 of KRASExperimental Design: A quantitative, mutation-enrichment next-generation sequencing test for detecting KRASG12/G13 mutations in urine cfDNA was developed, and results were compared with clinical testing of archival tumor tissue and plasma cfDNA from patients with advanced cancer.Results: With 90 to 110 mL of urine, the KRASG12/G13 cfDNA test had an analytical sensitivity of 0.002% to 0.006% mutant copies in wild-type background. In 71 patients, the concordance between urine cfDNA and tumor was 73% (sensitivity, 63%; specificity, 96%) for all patients and 89% (sensitivity, 80%; specificity, 100%) for patients with urine samples of 90 to 110 mL. Patients had significantly fewer KRASG12/G13 copies in urine cfDNA during systemic therapy than at baseline or disease progression (P = 0.002). Compared with no changes or increases in urine cfDNA KRASG12/G13 copies during therapy, decreases in these measures were associated with longer median time to treatment failure (P = 0.03).Conclusions: A quantitative, mutation-enrichment next-generation sequencing test for detecting KRASG12/G13 mutations in urine cfDNA had good concordance with testing of archival tumor tissue. Changes in mutated urine cfDNA were associated with time to treatment failure. Clin Cancer Res; 23(14); 3657-66. ©2017 AACR.

Universal Genomic Testing: The next step in oncological decision-making or a dead end street?

The concept of 'personalised medicine' aims at allocating patients to different treatment options based on individual characteristics to optimise treatment benefit and side effects. In oncology, personalised treatments coupled to biomarkers have led to the approval of targeted agents with high anti-tumour activity. However, these therapies are often limited to narrow, molecularly defined subsets of patients with a specific morphomolecular tumour profile. Recently, it became obvious that the same molecular alteration might drive oncogenesis in many different tumours, and it might be beneficial to target the alteration in a histology informed but entity-overarching way. Consequently, Universal Genomic Testing (UGT) of tumours encompassing panel sequencing to whole-exome and transcriptome sequencing is propagated to revolutionise oncology. This article will describe the developments leading to identification and application of potential biomarkers using UGT. On this basis, it will review the clinical evidence of this approach and summarise recommendations for the ongoing evaluation of UGT as the next step in oncological decision-making.

The Potential Value of the PI3K/Akt/mTOR Signaling Pathway for Assessing Prognosis in Cervical Cancer and as a Target for Therapy

Cervical cancer is a common gynecological cancer and a leading cause of cancer-related death in women globally. There is a need for the identification of prognostic and predictive biomarker for risk stratification. The phosphatidylinositol 3-kinase/protein kinase B/mammalian target of rapamycin (PI3K/Akt/mTOR) pathway is often dysregulated in cervical cancer, indicating that it may be a potential therapeutic target in the treatment of this malignancy, and could perhaps be used as a novel biomarker in the assessment of risk of developing cervical cancer. We aimed to provide an overview of the potential applications of the PI3K/Akt/mTOR pathway as biomarker for risk stratification, in predicting the prognosis of cervical cancer, and for developing new therapeutic approaches in patients with cervical cancer. J. Cell. Biochem. 118: 4163-4169, 2017. © 2017 Wiley Periodicals, Inc.

Synergistic interactions with PI3K inhibition that induce apoptosis

Activating mutations involving the PI3K pathway occur frequently in human cancers. However, PI3K inhibitors primarily induce cell cycle arrest, leaving a significant reservoir of tumor cells that may acquire or exhibit resistance. We searched for genes that are required for the survival of PI3K mutant cancer cells in the presence of PI3K inhibition by conducting a genome scale shRNA-based apoptosis screen in a PIK3CA mutant human breast cancer cell. We identified 5 genes (PIM2, ZAK, TACC1, ZFR, ZNF565) whose suppression induced cell death upon PI3K inhibition. We showed that small molecule inhibitors of the PIM2 and ZAK kinases synergize with PI3K inhibition. In addition, using a microscale implementable device to deliver either siRNAs or small molecule inhibitors in vivo, we showed that suppressing these 5 genes with PI3K inhibition induced tumor regression. These observations identify targets whose inhibition synergizes with PI3K inhibitors and nominate potential combination therapies involving PI3K inhibition.

Pilot study of sirolimus in patients with PIK3CA mutant/amplified refractory solid cancer

In patients with refractory cancer, the effect of additional chemotherapy is very limited. Targeted agents for molecular pathways associated with cancer cell progression and survival have emerged as attractive options in several cancer types. The current pilot study assessed the efficacy and safety of sirolimus in patients with refractory cancer with PIK3CA mutation/amplification. Refractory cancer patients with PIK3CA mutation/amplification were enrolled, irrespective of tumor-types. Enrolled patients received a daily dose of 1 mg sirolimus and one cycle defined as 28 days. An assessment of the efficacy and safety of sirolimus was performed. Overall, 4 patients were enrolled between October 2014 and April 2015. The median of 2.5 cycles of sirolimus was administered. Three patients had advanced gastric cancer and one had advanced cholangiocarcinoma. The overall response rate was 0%, three patients (75%) had stable disease following one cycle and one patient (25%) received sirolimus for 4 cycles without disease progression. The median progression free survival was 1.9 months [95% confidence interval (CI), 0.3–3.5 months], and the median overall survival was 3.6 months (95% CI, 0.4–6.8 months). Grade 3 or greater hematologic/non-hematologic toxicity was not observed. Grade 1 nausea was reported in one patient each. There were no treatment-associated mortalities. Sirolimus had modest efficacy and a tolerable toxicity-profile in patients with refractory cancer with PIK3CA mutation/amplification.

Profiling protein expression in circulating tumour cells using microfluidic western blotting

Circulating tumour cells (CTCs) are rare tumour cells found in the circulatory system of certain cancer patients. The clinical and functional significance of CTCs is still under investigation. Protein profiling of CTCs would complement the recent advances in enumeration, transcriptomic and genomic characterization of these rare cells and help define their characteristics. Here we describe a microfluidic western blot for an eight-plex protein panel for individual CTCs derived from estrogen receptor-positive (ER+) breast cancer patients. The precision handling and analysis reveals a capacity to assay sparingly available patient-derived CTCs, a biophysical CTC phenotype more lysis-resistant than breast cancer cell lines, a capacity to report protein expression on a per CTC basis and two statistically distinct GAPDH subpopulations within the patient-derived CTCs. Targeted single-CTC proteomics with the capacity for archivable, multiplexed protein analysis offers a unique, complementary taxonomy for understanding CTC biology and ascertaining clinical impact.

Circulating tumour cells (CTCs) are rare cells found in the blood of certain cancer patients. Here, the authors develop a cytometry tool that appends a microfluidic western blot to a CTC isolation workflow and apply it to profile a panel of proteins in single CTCs isolated from ER+ breast cancer patients.

Ginsenoside PPD's Antitumor Effect via Down-Regulation of mTOR Revealed by Super-Resolution Imaging

Derived from Panax ginseng, the natural product 20(S)-Protopanaxadiol (PPD) has been reported for its cytotoxicity against several cancer cell lines. The molecular mechanism is, however, not well understood. Here we show that PPD significantly inhibits proliferation, induces apoptosis and causes G2/M cell cycle arrest in human laryngeal carcinoma cells (Hep-2 cells). PPD also decreases the levels of proteins related to cell proliferation. Moreover, PPD-induced apoptosis is characterized by a dose-dependent down-regulation of Bcl-2 expression and up-regulation of Bax, and is accompanied by the activation of Caspase-3 as well. Further molecular mechanism is revealed by direct stochastic optical reconstruction microscopy (dSTORM)—a novel high-precision localization microscopy which enables effective resolution down to the order of 10 nm. It shows the expression and spatial arrangement of mTOR and its downstream effectors, demonstrating that this ginsenoside exerts its excellent anticancer effects via down-regulation of mTOR signaling pathway in Hep-2 cells. Taken together, our findings elucidate that the antitumor effect of PPD is associated with its regulation of mTOR expression and distribution, which encourages further studies of PPD as a promising therapeutic agent against laryngeal carcinoma.

Predicting clinical benefit from everolimus in patients with advanced solid tumors, the CPCT-03 study

Background

In this study, our aim was to identify molecular aberrations predictive for response to everolimus, an mTOR inhibitor, regardless of tumor type.

Methods

To generate hypotheses about potential markers for sensitivity to mTOR inhibition, drug sensitivity and genomic profiles of 835 cell lines were analyzed. Subsequently, a multicenter study was conducted. Patients with advanced solid tumors lacking standard of care treatment options were included and underwent a pre-treatment tumor biopsy to enable DNA sequencing of 1,977 genes, derive copy number profiles and determine activation status of pS6 and pERK. Treatment benefit was determined according to TTP ratio and RECIST. We tested for associations between treatment benefit and single molecular aberrations, clusters of aberrations and pathway perturbation.

Results

Cell line screens indicated several genes, such as PTEN (P = 0.016; Wald test), to be associated with sensitivity to mTOR inhibition. Subsequently 73 patients were included, of which 59 started treatment with everolimus. Response and molecular data were available from 43 patients. PTEN aberrations, i.e. copy number loss or mutation, were associated with treatment benefit (P = 0.046; Fisher's exact test).

Conclusion

Loss-of-function aberrations in PTEN potentially represent a tumor type agnostic biomarker for benefit from everolimus and warrants further confirmation in subsequent studies.

Evaluation of a novel approach to circulating tumor cell isolation for cancer gene panel analysis in patients with breast cancer

Liquid biopsy isolation of circulating tumor cells (CTCs) allows the genomic analysis of CTCs, which is useful in the determination of personalized cancer therapy. In the present study, CTCs from patients with breast cancer were enriched and successfully analyzed using cancer gene panel analysis. Blood samples from 11 patients with breast cancer were collected and CTCs enriched for using size-based filtration. The enriched CTCs were analyzed using immunofluorescence staining with antibodies directed against epithelial cell adhesion molecule (EpCAM) and cluster of differentiation 45. The genomic DNA of CTCs was extracted, amplified and 50 genes screened for mutations using the Ion AmpliSeq™ Cancer Hotspot Panel v2. EpCAM staining detected CTCs in 10/11 patients and the average CTC count was 3.9 in 5 ml blood. The average purity of enriched CTCs was 14.2±29.4% and the average amount of amplified DNA was 28.6±11.9 µg. Catalogue Of Somatic Mutations In Cancer mutations were detected in the CTCs and included IDH2, TP53, NRAS, IDH1, PDGFRA, HRAS, STK11, EGFR, PTEN, MLH1, PIK3CA, CDKN2A, KIT and SMARCB1. In conclusion, a novel size-based filtration approach for the isolation of CTCs was evaluated and successfully applied for the genomic analysis of CTCs from patients with breast cancer.

Comprehensive genomic profiling (CGP) of ovarian clear cell carcinomas (OCCC) identifies clinically relevant genomic alterations (CRGA) and targeted therapy options

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MTOR pathway genes are often mutated in ovarian clear cell carcinomas (OCCC).

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11.2% of OCCC have targetable alterations only in the mTOR pathway.

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MTOR pathway mutations in OCCC can underlie robust, lasting responses to everolimus.

Synthesis and Biological Evaluation of Novel 8-Morpholinoimidazo[1,2-a]pyrazine Derivatives Bearing Phenylpyridine/Phenylpyrimidine-Carboxamides

Herein we designed and synthesized three series of novel 8-morpholinoimidazo[1,2-a]pyrazine derivatives bearing phenylpyridine/phenylpyrimidine-carboxamides (compounds 12a–g, 13a–g and 14a–g). All the compounds were evaluated for their IC₅₀ values against three cancer cell lines (A549, PC-3 and MCF-7). Most of the target compounds exhibited moderate cytotoxicity against the three cancer cell lines. Two selected compounds 14b, 14c were further tested for their activity against PI3Kα kinase, and the results indicated that compound 14c showed inhibitory activity against PI3Kα kinase with an IC₅₀ value of 1.25 μM. Structure-activity relationships (SARs) and pharmacological results indicated that the replacement of the thiopyranopyrimidine with an imidazopyrazine was beneficial for the activity and the position of aryl group has a significant influence to the activity of these compounds. The compounds 13a–g in which an aryl group substituted at the C-4 position of the pyridine ring were more active than 12a–g substituted at the C-5 position. Moreover, the cytotoxicity of compounds 14a–g bearing phenylpyrimidine-carboxamides was better than that of the compounds 12a–g, 13a–g bearing phenylpyridine-carboxamides. Furthermore, the substituents on the benzene ring also had a significant impact on the cytotoxicity and the pharmacological results showed that electron donating groups were beneficial to the cytotoxicity.

A Review of mTOR Pathway Inhibitors in Gynecologic Cancer

The treatment of advanced gynecologic cancers remains palliative in most of cases. Although systemic treatment has entered into the era of targeted drugs the antitumor efficacies of current therapies are still limited. In this context there is a great need for more active treatment and rationally designed targeted therapies. The PI3K/AKT/mTOR is a signaling pathway in mammal cells that coordinates important cell activities. It has a critical function in the survival, growth, and proliferation of malignant cells and was object of important research in the last two decades. The mTOR pathway emerges as an attractive therapeutic target in cancer because it serves as a convergence point for many growth stimuli and, through its downstream substrates, controls cellular processes that contribute to the initiation and maintenance of cancer. Aberrant PI3K-dependent signaling occurs frequently in a wide range of tumor types, including endometrial, cervical, and ovarian cancers. The present study reviewed the available evidence regarding the potential impact of some mTOR pathway inhibitors in the treatment of gynecological cancer. Few advances in medical management have occurred in recent years in the treatment of advanced or recurrent gynecological malignancies, and a poor prognosis remains. Rationally designed molecularly targeted therapy is an emerging and important option in this setting; then more investigation in PI3K/AKT/mTOR pathway-targeted therapies is warranted.

Cell Signaling Pathways in Brain Tumors

Primary brain tumors, particularly glioblastoma, are associated with significant morbidity and are often recalcitrant to standard therapies. In recent years, brain tumors have been the focus of large-scale genomic sequencing efforts, providing unprecedented insight into the genomic aberrations and cellular signaling mechanisms that drive these cancers. Discoveries from these efforts have translated into novel diagnostic algorithms, biomarkers, and therapeutic strategies in Neuro-Oncology. However, the cellular mechanisms that drive brain tumors are heterogeneous and complex: applying this new knowledge to improve patient outcomes remains a challenge. Efforts to characterize and target these molecular vulnerabilities are evolving.

Dual-activity PI3K-BRD4 inhibitor for the orthogonal inhibition of MYC to block tumor growth and metastasis

MYC is a major cancer driver but is documented to be a difficult therapeutic target itself. Here, we report on the biological activity, the structural basis, and therapeutic effects of the family of multitargeted compounds that simultaneously disrupt functions of two critical MYC-mediating factors through inhibiting the acetyllysine binding of BRD4 and the kinase activity of PI3K. We show that the dual-action inhibitor impairs PI3K/BRD4 signaling in vitro and in vivo and affords maximal MYC down-regulation. The concomitant inhibition of PI3K and BRD4 blocks MYC expression and activation, promotes MYC degradation, and markedly inhibits cancer cell growth and metastasis. Collectively, our findings suggest that the dual-activity inhibitor represents a highly promising lead compound for the development of novel anticancer therapeutics.

Berberine-sonodynamic therapy induces autophagy and lipid unloading in macrophage

Impaired autophagy in macrophages accompanies the progression of atherosclerosis and contributes to lipid loading in plaques and ineffective lipid degradation. Therefore, evoking autophagy and its associated cholesterol efflux may provide a therapeutic treatment for atherosclerosis. In the present study, berberine-mediated sonodynamic therapy (BBR-SDT) was used to induce autophagy and cholesterol efflux in THP-1 macrophages and derived foam cells. Following BBR-SDT, autophagy was increased in the macrophages, autophagy resistance in the foam cells was prevented, and cholesterol efflux was induced. The first two effects were blocked by the reactive oxygen species scavenger, N-acetyl cysteine. BBR-SDT also reduced the phosphorylation of Akt and mTOR, two key molecules in the PI3K/AKT/mTOR signaling pathway, which is responsible for inducing autophagy. Correspondingly, treatment with the autophagy inhibitor, 3-methyladenine, or the PI3K inhibitor, LY294002, abolished the autophagy-induced effects of BBR-SDT. Furthermore, induction of cholesterol efflux by BBR-SDT was reversed by an inhibition of autophagy by 3-methyladenine or by a small interfering RNA targeting Atg5. Taken together, these results demonstrate that BBR-SDT effectively promotes cholesterol efflux by increasing reactive oxygen species generation, and this subsequently induces autophagy via the PI3K/AKT/mTOR signaling pathway in both ‘normal' macrophages and lipid-loaded macrophages (foam cells). Thus, BBR-SDT may be a promising atheroprotective therapy to inhibit the progression of atherosclerosis and should be further studied.

Chemoresistance and targeted therapies in ovarian and endometrial cancers

Gynecological cancers are known for being very aggressive at their advanced stages. Indeed, the survival rate of both ovarian and endometrial cancers is very low when diagnosed lately and the success rate of current chemotherapy regimens is not very efficient. One of the main reasons for this low success rate is the acquired chemoresistance of these cancers during their progression. The mechanisms responsible for this acquired chemoresistance are numerous, including efflux pumps, repair mechanisms, survival pathways (PI3K/AKT, MAPK, EGFR, mTOR, estrogen signaling) and tumor suppressors (P53 and Par-4). To overcome these resistances, a new type of therapy has emerged named targeted therapy. The principle of targeted therapy is simple, taking advantage of changes acquired in malignant cancer cells (receptors, proteins, mechanisms) by using compounds specifically targeting these, thus limiting their action on healthy cells. Targeted therapies are emerging and many clinical trials targeting these pathways, frequently involved in chemoresistance, have been tested on gynecological cancers. Despite some targets being less efficient than expected as mono-therapies, the combination of compounds seems to be the promising avenue. For instance, we demonstrate using ChIP-seq analysis that estrogen downregulate tumor suppressor Par-4 in hormone-dependent cells by directly binding to its DNA regulatory elements and inhibiting estrogen signaling could reinstate Par-4 apoptosis-inducing abilities. This review will focus on the chemoresistance mechanisms and the clinical trials of targeted therapies associated with these, specifically for endometrial and ovarian cancers.

Next-generation sequencing reveals somatic mutations that confer exceptional response to everolimus

Background

Given the modest responses to everolimus, a mTOR inhibitor, in multiple tumor types, there is a pressing need to identify predictive biomarkers for this drug. Using targeted ultra-deep sequencing, we aimed to explore genomic alterations that confer extreme sensitivity to everolimus.

Results

We collected formalin-fixed paraffin-embedded tumor/normal pairs from 39 patients (22 with exceptional clinical benefit, 17 with no clinical benefit) who were treated with everolimus across various tumor types (13 gastric cancers, 15 renal cell carcinomas, 2 thyroid cancers, 2 head and neck cancer, and 7 sarcomas). Ion AmpliSeq^TM Comprehensive Cancer Panel was used to identify alterations across all exons of 409 target genes. Tumors were sequenced to a median coverage of 552x. Cancer genomes are characterized by 219 somatic single-nucleotide variants (181 missense, 9 nonsense, 7 splice-site) and 22 frameshift insertions/deletions, with a median of 2.1 mutations per Mb (0 to 12.4 mutations per Mb). Overall, genomic alterations with activating effect on mTOR signaling were identified in 10 of 22 (45%) patients with clinical benefit and these include MTOR, TSC1, TSC2, NF1, PIK3CA and PIK3CG mutations. Recurrently mutated genes in chromatin remodeling genes (BAP1; n = 2, 12%) and receptor tyrosine kinase signaling (FGFR4; n = 2, 12%) were noted only in patients without clinical benefit.

Conclusions

Regardless of different cancer types, mTOR-pathway-activating mutations confer sensitivity to everolimus. Targeted sequencing of mTOR pathway genes facilitates identification of potential candidates for mTOR inhibitors.