The poly (ADP-ribose) polymerase (PARP) inhibitor olaparib is FDA approved for the treatment of BRCA-mutated breast, ovarian and pancreatic cancers. Olaparib inhibits PARP1/2 enzymatic activity and ...traps PARP1 on DNA at single-strand breaks, leading to replication-induced DNA damage that requires BRCA1/2-dependent homologous recombination repair. Moreover, DNA damage response pathways mediated by the ataxia-telangiectasia mutated (ATM) and ataxia-telangiectasia mutated and Rad3-related (ATR) kinases are hypothesised to be important survival pathways in response to PARP-inhibitor treatment. Here, we show that olaparib combines synergistically with the ATR-inhibitor AZD6738 (ceralasertib), in vitro, leading to selective cell death in ATM-deficient cells. We observe that 24 h olaparib treatment causes cells to accumulate in G2-M of the cell cycle, however, co-administration with AZD6738 releases the olaparib-treated cells from G2 arrest. Selectively in ATM-knockout cells, we show that combined olaparib/AZD6738 treatment induces more chromosomal aberrations and achieves this at lower concentrations and earlier treatment time-points than either monotherapy. Furthermore, single-agent olaparib efficacy in vitro requires PARP inhibition throughout multiple rounds of replication. Here, we demonstrate in several ATM-deficient cell lines that the olaparib and AZD6738 combination induces cell death within 1-2 cell divisions, suggesting that combined treatment could circumvent the need for prolonged drug exposure. Finally, we demonstrate in vivo combination activity of olaparib and AZD6738 in xenograft and PDX mouse models with complete ATM loss. Collectively, these data provide a mechanistic understanding of combined PARP and ATR inhibition in ATM-deficient models, and support the clinical development of AZD6738 in combination with olaparib.
•11q13 amplification is a key event in oral carcinogenesis.•We examine the 11q13 amplicon and its amplicon cores and drivers in OSCC.•We review the oncogenic implications of oncogenes in the 11q13 ...amplicon.•We analyze the therapeutic targeting of chromosome band 11q13 in HNSCC and OSCC.•We discuss future research lines.
An important event in oral carcinogenesis is the amplification of chromosomal band 11q13, in which numerous oncogenes and some tumor-suppressor genes are localized and frequently co-amplified during the malignant transformation of oral epithelium. The objectives of this study were to review published data on the involvement of 11q13 amplification in oral cancer, to provide an update on novel concepts and terminology related to gene amplification, and to explore the composition of the 11q13 amplicon in OSCC, including its most relevant amplicon cores and potential drivers. We report on the critical oncogenes and tumor-suppressor genes in 11q13 that may play a major role in oral cancer, focusing on their functions, on the characteristics acquired by their amplification, and on their clinicopathological implications. Finally, we discuss the possible usefulness of the 11q13 region as a therapeutic target in oral cancer.
Genetically engineered mouse models of cancer can be used to filter genome‐wide expression datasets generated from human tumours and to identify gene expression alterations that are functionally ...important to cancer development and progression. In this study, we have generated RNAseq data from tumours arising in two established mouse models of prostate cancer, PB‐Cre/PtenloxP/loxP and p53loxP/loxPRbloxP/loxP, and integrated this with published human prostate cancer expression data to pinpoint cancer‐associated gene expression changes that are conserved between the two species. To identify potential therapeutic targets, we then filtered this information for genes that are either known or predicted to be druggable. Using this approach, we revealed a functional role for the kinase MELK as a driver and potential therapeutic target in prostate cancer. We found that MELK expression was required for cell survival, affected the expression of genes associated with prostate cancer progression and was associated with biochemical recurrence.
Synopsis
Genetically engineered mouse models (GEMM) of human cancers can be used as “biological filters” to identify genes that are important to cancer development and prioritise potential therapeutic targets. The example of MELK in prostate cancer.
Comparisons of high‐throughput sequencing data from two GEMM of prostate cancer with human prostate cancer gene expression data revealed that human and murine tumours share common gene expression alterations.
Integration of human and murine gene expression data was used to identify potential therapeutic targets in prostate cancer, including the protein kinase MELK.
MELK is overexpressed in prostate cancer and associated with poor prognosis.
Silencing of MELK or treatment with an inhibitor targeting MELK resulted in induction of apoptosis in prostate cancer cells in vitro and in vivo.
Genetically engineered mouse models (GEMM) of human cancers can be used as “biological filters” to identify genes that are important to cancer development and prioritise potential therapeutic targets. The example of MELK in prostate cancer.
The androgen receptor (AR) regulates prostate cell growth in man, and prostate cancer is the commonest cancer in men in the UK. We present a comprehensive analysis of AR binding sites in human ...prostate cancer tissues, including castrate-resistant prostate cancer (CRPC). We identified thousands of AR binding sites in CRPC tissue, most of which were not identified in PC cell lines. Many adjacent genes showed AR regulation in xenografts but not in cultured LNCaPs, demonstrating an in-vivo-restricted set of AR-regulated genes. Functional studies support a model of altered signaling in vivo that directs AR binding. We identified a 16 gene signature that outperformed a larger in-vitro-derived signature in clinical data sets, showing the importance of persistent AR signaling in CRPC.
► AR ChIP-seq in primary clinical material reveals persistent AR signaling in CRPC ► A tissue-specific transcriptional network exists in human prostate tissue ► AR signaling in CRPC is maintained via a distinct set of AR targets ► A core 16 gene set derived from this data is clinically relevant
We have previously demonstrated that Stat3 regulates lysosomal-mediated programmed cell death (LM-PCD) during mouse mammary gland involution in vivo. However, the mechanism that controls the release ...of lysosomal cathepsins to initiate cell death in this context has not been elucidated. We show here that Stat3 regulates the formation of large lysosomal vacuoles that contain triglyceride. Furthermore, we demonstrate that milk fat globules (MFGs) are toxic to epithelial cells and that, when applied to purified lysosomes, the MFG hydrolysate oleic acid potently induces lysosomal leakiness. Additionally, uptake of secreted MFGs coated in butyrophilin 1A1 is diminished in Stat3-ablated mammary glands and loss of the phagocytosis bridging molecule MFG-E8 results in reduced leakage of cathepsins in vivo. We propose that Stat3 regulates LM-PCD in mouse mammary gland by switching cellular function from secretion to uptake of MFGs. Thereafter, perturbation of lysosomal vesicle membranes by high levels of free fatty acids results in controlled leakage of cathepsins culminating in cell death.
A 2‐day meeting was held by members of the UK Quantitative Systems Pharmacology Network (<http://www.qsp‐uk.net/>) in November 2018 on the topic of Translational Challenges in Oncology. Participants ...from a wide range of backgrounds were invited to discuss current and emerging modeling applications in nonclinical and clinical drug development, and to identify areas for improvement. This resulting perspective explores opportunities for impactful quantitative pharmacology approaches. Four key themes arose from the presentations and discussions that were held, leading to the following recommendations:
Evaluate the predictivity and reproducibility of animal cancer models through precompetitive collaboration.
Apply mechanism of action (MoA) based mechanistic models derived from nonclinical data to clinical trial data.
Apply MoA reflective models across trial data sets to more robustly quantify the natural history of disease and response to differing interventions.
Quantify more robustly the dose and concentration dependence of adverse events through mathematical modelling techniques and modified trial design.
Ovarian cancer is the deadliest gynecologic cancer, with a 5-year survival rate of 30%, when the disease has spread throughout the peritoneal cavity. We investigated the efficacy to delay disease ...progression by the DNA-dependent protein kinase (DNA-PK) inhibitor AZD7648, administered in combination with two of the therapeutic options for patient management: either pegylated liposomal doxorubicin (PLD) or the PARP inhibitor olaparib. Patient-derived ovarian cancer xenografts (OC-PDX) were transplanted subcutaneously to evaluate the effect of treatment on tumor growth, or orthotopically in the peritoneal cavity to evaluate the effect on metastatic spread. AZD7648 was administered orally in combination with PLD (dosed intravenously) or with olaparib (orally). To prove the inhibition of DNA-PK in the tumors, we measured pDNA-PKcs, pRPA32, and γH2AX, biomarkers of DNA-PK activity. AZD7648 enhanced the therapeutic efficacy of PLD in all the OC-PDXs tested, regardless of their BRCA status or sensitivity to cisplatin or PLD. The treatment caused disease stabilization, which persisted despite therapy discontinuation for tumors growing subcutaneously, and significantly impaired the abdominal metastatic dissemination, prolonging the lifespan of mice implanted orthotopically. AZD7648 potentiated the efficacy of olaparib in BRCA-deficient OC-PDXs but did not sensitize BRCA-proficient OC-PDXs to olaparib, despite an equivalent inhibition of DNA-PK, suggesting the need of a preexisting olaparib activity to benefit from the addition of AZD7648. This work suggests that AZD7648, an inhibitor of DNA-PK, dosed in combination with PLD or olaparib is an exciting therapeutic option that could benefit patients with ovarian cancer and should be explored in clinical trials.
DNA-PK is a key component within the DNA damage response, as it is responsible for recognizing and repairing double-strand DNA breaks (DSBs) via non-homologous end joining. Historically it has been ...challenging to identify inhibitors of the DNA-PK catalytic subunit (DNA-PKcs) with good selectivity versus the structurally related PI3 (lipid) and PI3K-related protein kinases. We screened our corporate collection for DNA-PKcs inhibitors with good PI3 kinase selectivity, identifying compound 1. Optimization focused on further improving selectivity while improving physical and pharmacokinetic properties, notably co-optimization of permeability and metabolic stability, to identify compound 16 (AZD7648). Compound 16 had no significant off-target activity in the protein kinome and only weak activity versus PI3Kα/γ lipid kinases. Monotherapy activity in murine xenograft models was observed, and regressions were observed when combined with inducers of DSBs (doxorubicin or irradiation) or PARP inhibition (olaparib). These data support progression into clinical studies (NCT03907969).
Poly ADP-ribose polymerase inhibitors (PARPi) have transformed ovarian cancer (OC) treatment, primarily for tumours deficient in homologous recombination repair. Combining VEGF-signalling inhibitors ...with PARPi has enhanced clinical benefit in OC. To study drivers of efficacy when combining PARP inhibition and VEGF-signalling, a cohort of patient-derived ovarian cancer xenografts (OC-PDXs), representative of the molecular characteristics and drug sensitivity of patient tumours, were treated with the PARPi olaparib and the VEGFR inhibitor cediranib at clinically relevant doses. The combination showed broad anti-tumour activity, reducing growth of all OC-PDXs, regardless of the homologous recombination repair (HRR) mutational status, with greater additive combination benefit in tumours poorly sensitive to platinum and olaparib. In orthotopic models, the combined treatment reduced tumour dissemination in the peritoneal cavity and prolonged survival. Enhanced combination benefit was independent of tumour cell expression of receptor tyrosine kinases targeted by cediranib, and not associated with change in expression of genes associated with DNA repair machinery. However, the combination of cediranib with olaparib was effective in reducing tumour vasculature in all the OC-PDXs. Collectively our data suggest that olaparib and cediranib act through complementary mechanisms affecting tumour cells and tumour microenvironment, respectively. This detailed analysis of the combined effect of VEGF-signalling and PARP inhibitors in OC-PDXs suggest that despite broad activity, there is no dominant common mechanistic inter-dependency driving therapeutic benefit.
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