Tankyrase translation With a few pharmas entering the search for tankyrase inhibitors for cancer, Merck KGaA is hedging its bets by joining forces with The Institute of Cancer Research and the Wellcome Trust to accelerate development of selective inhibitors of the enzymes. The two tankyrases—tankyrase TRF1-interacting ankyrin-related ADP-ribose polymerase (TNKS) and TNKS2—are members of the poly(ADP-ribose) polymerase (PARP) family of enzymes that transfer ADP-ribose groups to a range of cellular proteins and are upregulated in a variety of cancers. Last year, several groups identified selective compounds that inhibited tankyrases but not other PARPs, including teams at the University of Oslo, Novartis AG’s Novartis Institutes for BioMedical Research and Roche’s Genentech Inc. unit.1,2 However, Genentech’s program is no longer active, and the current development status of the University of Oslo and Novartis compounds was unavailable at press time. Under the terms of the Merck KGaA deal, the pharma’s Merck Serono unit and the team at the Institute of Cancer Research (ICR) will initially focus on translating existing leads from both groups into the clinic and identifying backup compounds. Merck Serono will make milestone payments to ICR and Wellcome—which originally funded the program at ICR—based on regulatory and sales goals, plus royalty payments on net sales of future products discovered or developed under the agreement. The partners will combine their portfolios of tankyrase inhibitors, continue parallel screening efforts and work together on biomarker identification and animal studies. The ICR team is led by Alan Ashworth, a professor of molecular biology at ICR, and Chris Lord, team leader and reader in cancer biology and therapeutics at ICR. The two have experience with small molecule inhibitors of PARP. Andree Blaukat, head of translational innovation platform oncology at Merck Serono, told SciBX that both partners have confirmed the selectivity of their initial leads and that studies are under way to profile the therapeutic window of the compounds. “Our tankyrase inhibitors are also very selective, so they do not inhibit other PARPs at all,” he said. Blaukat added that biomarker identification was also one of the key goals. “We will only move programs forward if we have biomarkers either preclinically validated or a very solid hypothesis for additional markers,” he said. Although Merck declined to disclose funding details, Blaukat said that both Merck and ICR are contributing resources to the collaboration. He added that each partner will contribute scientifically based on its particular strengths—for example, by performing animal models or biophysical analyses that are well established at the respective institutions.
Breast cancerHomeobox A1 (HOXA1)vitro and mouse studies suggest depleting HOXA1 could prevent progression of early breast cancer lesions.Computational evaluation and comparison of networks of gene expression changes in tumorigenic and wild-type mouse mammary glands identified Hoxa1 as a possible modulator of early tumor progression.In 3D cell culture, siRNA knockdown of Hoxa1 caused mammary epithelial tumor cells to adopt wildtype tissue architectures.In a mouse model of human breast cancer, intraductal delivery of lipid nanoparticle-formulated siRNA targeting Hoxa1 decreased cell proliferation and tumor incidence compared with nonspecific siRNA.Next steps include profiling Hoxa1 mutations in human breast cancer and building related computational models based on human clinical samples.
Atherosclerosis Myosin regulatory light chain interacting protein (MYLIP; MIR; IDOL); liver X receptor (LXR) Nonhuman primate studies suggest combining MYLIP inhibitors with LXR agonists could help treat atherosclerosis.LXR agonists used in atherosclerosis treatment raise plasma low-density lipoprotein (LDL) levels as a side effect.In normal nonhuman primates, an LXR agonist increased plasma LDL levels and hepatic Mylip mRNA levels compared with vehicle.In nonhuman primates fed a high-fat diet, an antisense oligonucleotide against MYLIP attenuated LXR agonist-induced increases in plasma LDL levels.Ongoing work includes screening for small molecule MYLIP inhibitors.Exelixis Inc. and Bristol-Myers Squibb Co. have XL041 (BMS-852927), a small molecule modulator of LXR, in Phase I testing to treat metabolic syndrome.Vitae Pharmaceuticals Inc. has two LXR-b (NR1H2) agonists in preclinical development: VTP-38443 for acute coronary syndrome and VTP-38543 for dermatitis.
Dystrophia myotonica protein kinase (DMPK)In vitro and mouse studies identified a DMPK CUG repeat-binding inhibitor that could help treat myotonic dystrophy type 1 (DM1).DM1 is caused by CUG repeats in the DMPK mRNA that bind and sequester the splicing regulator muscleblind (MBNL1).In HeLa cells expressing CUG repeatcontaining DMPK, an inhibitor that bound the repeats and blocked binding to MBNL1 decreased formation of ribonuclear foci and partially corrected splicing of two genes compared with no treatment.In a transgenic Drosophila model of DM1, the inhibitor suppressed disease phenotypes.Next steps could include testing the inhibitor in additional DM1 models and improving its potency.
Assays & screensNano-plasmonic exosome (nPLEX) sensor for high throughput, label-free, quantitative analysis of exosome proteins Patient sample studies suggest an nPLEX sensor can help diagnose and/or monitor cancer treatment.The nPLEX sensor is comprised of an array of nanopores in a metal film functionalized with affinity ligands for specific proteins and a miniaturized imaging system.Binding of affinity ligands to proteins on exosomes results in a spectral shift.In ascites derived from patients with ovarian cancer, epithelial cell adhesion molecule (EpCAM) and CD24 arrays detected more exosomes and higher levels of protein per exosome than what was seen in ascites derived from patients with cirrhosis.Next steps include performing large-scale proteomic analysis on exosomes.
Assays & screensAssay to detect circulating methylated DNA (cMethDNA) to detect and monitor breast cancerIn vitro studies suggest a cMethDNA assay could help detect and monitor tumor burden.The cMethDNA assay amplifies and measures methylation of 10 genes with low methylation in normal cells but high methylation in breast cancer cells.The assay detected cancer with 96.4% specificity and 91.7% sensitivity in a set of 24 cancer and 28 normal samples, and results were validated in an additional 33 cancer and 27 normal samples.In samples from patients who responded to chemotherapy, cMethDNA levels were lower than those in samples from patients who had progressive disease.Next steps include validating clinical utility to monitor response to chemotherapy over time.
Transmembrane 6 superfamily member 2 (TM6SF2) Studies in human samples and mice suggest inhibiting TM6SF2 could help lower total cholesterol levels.In 5,771 Norwegians, genomewide assessment of coding variants identified an association between the rs58542926 SNP in TM6SF2 and low total cholesterol levels.In mice, Tm6sf2 overexpression in the liver increased total cholesterol compared with overexpression of a control gene.In mice, shRNA against Tm6sf2 decreased total cholesterol levels compared with control shRNA.Next steps could include identifying carriers of the rs58542926 SNP in clinical trials of lipid-modulating therapies.
Berg taps into tissue banks; somatic cell nuclear transfer may be catching up to iPS cell technology; a roundup of public-private partnerships.
Drug platformsHexamer-forming mAbs that activate the complement system mAbs engineered with mutations that promote hexamer formation could help treat infections and cancer by activating the complement system.The complement system is a part of the innate immune system that helps to eliminate pathogens and tumor cells.In cell culture, multiple IgGs engineered with an E345R mutation had greater complement-dependent cytotoxicity than unmodified variants.In vitro, IgGs with the E345R mutation were better than control IgGs at forming hexameric structures that activated complement component 1 q subcomponent (C1q) after binding to their target antigen.Next steps include selecting complement activation-enhancing mutations and specific mAb variants to use in Genmab A/S' HexaBody platform for generating therapeutic antibodies.Genmab uses its HexaBody platform to design mAbs that have an improved ability to eliminate pathogens and tumor cells while retaining their regular structure and specificity.
Clustered, regularly interspaced short palindromic repeats (CRISPR) genome editing to produce genetically modified monkeys Primate studies suggest CRISPR could be used to develop genetically modified monkeys that model disease.In single-cell cynomolgus monkey embryos, injection of a pool of five single guide RNAs (sgRNAs) targeting peroxisome proliferation-activated receptor-g (PPARG; PPARg), recombinant activating gene 1 (RAG1) and nuclear receptor subfamily 0 group B member 1 (NR0B1) plus CRISPR-associated 9 (Cas9) mRNA resulted in embryos with simultaneous disruptions in two target genes.In infant monkeys born after embryos were transferred to female monkeys, umbilical cord, placenta and ear puncture tissues from twin monkeys had the same genetic modifications in Pparg and Rag1.Next steps include developing germline-modified monkeys using the strategy.
Transformationassociated recombination (TAR)-based method to capture large, biosynthetic bacterial gene clustersA TAR-based approach to isolate bacterial gene clusters could aid the synthesis of natural products including antibiotics.In yeast, TAR was used to assemble a contiguous 67 kb region from the marine actinomycete Saccharomonospora sp. that contained 20 transcriptionally silent open reading frames including a biosynthetic gene cluster.Subsequent deletion of an inhibitory gene, heterologous expression in a model biosynthetic host and structural characterization identified the cluster's product as taromycin A, an antibiotic similar to Cubicin daptomycin.Next steps include streamlining the TAR-based approach for high throughput screening of biosynthetic microbial gene clusters.Cubist Pharmaceuticals Inc. markets Cubicin to treat bacteremia and skin and skin structure infections.
Cushing's diseaseProtein kinase cAMP-dependent catalytic-a (PRKACA) L205R Genetic sequencing studies identified an activating PRKACA mutation in Cushing's disease that could help model the disorder.In 49 adrenocortical tumor samples from patients with Cushing's disease, the somatic PRKACA L205R mutation was found in 55.1% of tumors and specifically in 69.1% of the benign adrenocortical adenoma tumor subset.In human cells, overexpression of PRKACA L205R increased phosphorylation of PRKACA substrates compared with wild-type PRKACA expression, suggesting it is an activating mutation.Next steps include developing a transgenic mouse model of Cushing's disease based on the findings.
A UNC Chapel Hill team has found a way to block multiple pain receptors by antagonizing the lipid kinase PIP5K1C. Although a PIP5K1C inhibitor alleviates chronic pain in multiple mouse models, the lethality of PIP5K1C mutations suggests that titrating the right dose will be key for safety.
Mouse model of Crohn's diseaseMice with the T300A mutation in autophagy related 16-like 1 (Atg16l1) could be useful as a model for studying the biology of Crohn's disease and evaluating therapeutic candidates.In the mouse model, knock-in of a Crohn's disease-associated T300A Atg16l1 variant resulted in abnormal intestinal cell morphology and impaired autophagy and led to greater intestinal bacterial replication and higher proinflammatory cytokine production than expression of wild-type Atg16l1.Next steps could include identifying conditions that lead to Crohn's disease pathogenesis in the model.
Assays & screensOne-bead, onecompound peptoidencoded a-helix mimetic library to identify chaperones or inhibitors of proteinprotein interactions Cell culture studies suggest a one-bead, one-compound peptoid-encoded a-helix mimetic library could be used to identify chaperones or inhibitors of a-helix-mediated proteinprotein interactions.Each bead displays one of 1,458 triazinepiperazine-triazine-based a-helix mimetics on the outside and a peptoid coding tag on the inside, enabling identification of the corresponding inhibitory mimetic.A screen of the one-bead, one-compound library against the myeloid leukemia cell differentiation protein (MCL1) identified two MCL1-binding compounds that also antagonized the interaction between MCL1 and the proapoptotic protein Bcl2 homology domain 3 (BH3).A screen of the library against recombinant a-synuclein (SNCA) protein also identified two SNCA-binding compounds that delayed the onset of SNCA aggregation.Ongoing work includes optimizing the identified compounds and preparing more diverse and larger libraries of a-helix mimetics to screen against different targets.
