Lead Drug Candidates Research Articles

Abstract 5759: Discovery of a novel claudin 6 (CLDN6) specific monoclonal antibody

Abstract Claudin 6 (CLDN6) is a tight junction molecule that is involved in cell to cell adhesion of epithelial and endothelial cell sheets. CLDN6 is considered an oncofetal protein which is not expressed in normal human tissue but is expressed in some cancers such as endometrial, ovarian and testis cancer. Expression of CLDN6 in endometrial and urothelial cancer leads to a poor prognosis. The problem of developing antibodies against CLDN6 is that the family member claudin 9 (CLDN9) is highly homologous, only varying by 2 amino acids in the extracellular domain. To address this need, Integral Molecular has developed the MPS Discovery Engine® to enable the isolation, characterization, and engineering of monoclonal antibodies for tight junction proteins, GPCRs, ion channels, and transporters. MPS utilizes a collection of technologies to address each of the barriers to monoclonal antibody development against the native extracellular epitopes of multispan membrane proteins. These include, antigen engineering to attain high levels of surface expression, DNA and Lipoparticle immunization to present native epitopes to the immune system, diverse immunization host species to deal with highly conserved proteins, Lipoparticles (high concentration native membrane proteins) to enable phage display, microfludic B-cell isolation to isolate rare MAbs, and shotgun mutagenesis (comprehensive alanine scanning) for epitope mapping. Using the MPS Discovery Engine® we were able to successfully screen a large panel of clones for claudin 6 specificity. From these clones there were 72 potential antibodies that reacted with either claudin 6 or 6/9. A subset of these antibodies reacted only to claudin 6 and not to claudin 9 which has led to our lead drug candidate. With our MPS Discovery Engine® platform, we have the ability to target intact, conformationally specific, and functional antibodies to multipass membrane proteins. Citation Format: Lewis J. Stafford, Brad Screnci, Chidananda Sulli, Erin Rosenberg, Nicholas Molino, David Tucker, Jonathan Sullivan, Trevor Barnes, Jennifer Pfaff, Tanmayee Hazarika, Thomas Charpentier, Samantha Gilman, Rebecca Rimkunas, Rona Wilf, Sharon Willis, Benjamin Doranz, Joseph Rucker, Ross Chambers. Discovery of a novel claudin 6 (CLDN6) specific monoclonal antibody [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 5759.

Pro region engineering of nerve growth factor by deep mutational scanning enables a yeast platform for conformational epitope mapping of anti-NGF monoclonal antibodies.

Nerve growth factor (NGF) plays a central role in multiple chronic pain conditions. As such, anti-NGF monoclonal antibodies (mAbs) that function by antagonizing NGF downstream signaling are leading drug candidates for non-opioid pain relief. To evaluate anti-canine NGF (cNGF) mAbs we sought a yeast surface display platform of cNGF. Both mature cNGF and pro-cNGF displayed on the yeast surface but bound conformationally sensitive mAbs at most 2.5-fold in mean fluorescence intensity above background, suggesting that cNGF was mostly misfolded. To improve the amount of folded, displayed cNGF, we used comprehensive mutagenesis, FACS, and deep sequencing to identify point mutants in the pro-region of canine NGF that properly enhance the folded protein displayed on the yeast surface. Out of 1,737 tested single point mutants in the pro region, 49 increased the amount of NGF recognized by conformationally sensitive mAbs. These gain-of-function mutations cluster around residues A-61-P-26. Gain-of-function mutants were additive, and a construct containing three mutations increased amount of folded cNGF to 23-fold above background. Using this new cNGF construct, fine conformational epitopes for tanezumab and three anti-cNGF mAbs were evaluated. The epitope revealed by the yeast experiments largely overlapped with the tanezumab epitope previously determined by X-ray crystallography. The other mAbs showed site-specific differences with tanezumab. As the number of binding epitopes of functionally neutralizing anti-NGF mAbs on NGF are limited, subtle differences in the individual interacting residues on NGF that bind each mAb contribute to the understanding of each antibody and variations in its neutralizing activity. These results demonstrate the potential of deep sequencing-guided protein engineering to improve the production of folded surface-displayed protein, and the resulting cNGF construct provides a platform to map conformational epitopes for other anti-neurotrophin mAbs.

Novartis to acquire AveXis

Novartis plans to acquire the neurological gene therapy firm AveXis for $8.7 billion. The purchase will bolster the Swiss giant’s standing as a big pharma leader in the emerging gene therapy field. AveXis’s leading drug candidate is its gene therapy to treat infants with spinal muscular atrophy type 1 (SMA1), a devastating genetic disease, sometimes called “floppy baby syndrome,” that causes weak muscles and difficulty breathing. Only 8% of afflicted infants survive to 20 months. In November, a study showed that all 15 infants treated with AveXis’s gene therapy for SMA1 were alive after 20 months (N. Engl. J. Med. 2017, DOI: 10.1056/nejmoa1706198). “Those kids were dying, and the outcomes look really good at this point,” Mark A. Kay, a director of the human gene therapy program at Stanford University School of Medicine, told C&EN in November when the study was released. Gene therapy enthusiasm grew even more in December

Computational Analysis for the Rational Design of Anti-Amyloid Beta (Aβ) Antibodies.

Alzheimer's disease (AD) is a neurodegenerative disorder that lacks effective treatment options. Anti-amyloid beta (Aβ) antibodies are the leading drug candidates to treat AD, but the results of clinical trials have been disappointing. Introducing rational mutations into anti-Aβ antibodies to increase their effectiveness is a way forward, but the path to take is unclear. In this study, we demonstrate the use of computational fragment-based docking and MMPBSA binding free energy calculations in the analysis of anti-Aβ antibodies for rational drug design efforts. Our fragment-based docking method successfully predicts the emergence of the common EFRH epitope. MD simulations coupled with MMPBSA binding free energy calculations are used to analyze scenarios described in prior studies, and we computationally introduce rational mutations into PFA1 to predict mutations that can improve its binding affinity toward the pE3-Aβ3-8 form of Aβ. Two out of our four proposed mutations are predicted to stabilize binding. Our study demonstrates that a computational approach may lead to an improved drug candidate for AD in the future.

Molecular Docking: From Lock and Key to Combination Lock.

Accurate modeling of protein ligand binding is an important step in structure-based drug design, is a useful starting point for finding new lead compounds or drug candidates. The 'Lock and Key' concept of protein-ligand binding has dominated descriptions of these interactions, and has been effectively translated to computational molecular docking approaches. In turn, molecular docking can reveal key elements in protein-ligand interactions-thereby enabling design of potent small molecule inhibitors directed against specific targets. However, accurate predictions of binding pose and energetic remain challenging problems. The last decade has witnessed more sophisticated molecular docking approaches to modeling protein-ligand binding and energetics. However, the complexities that confront accurate modeling of binding phenomena remain formidable. Subtle recognition and discrimination patterns governed by three-dimensional features and microenvironments of the active site play vital roles in consolidating the key intermolecular interactions that mediates ligand binding. Herein, we briefly review contemporary approaches and suggest that future approaches treat protein-ligand docking problems in the context of a 'combination lock' system.

Merck and KalVista sign diabetes drug pact

Merck & Co. will pay $9 million for a 9.9% stake in the protease inhibitor developer KalVista Pharmaceuticals. Merck is also giving KalVista $37 million up front for its lead drug candidate, a smal...

BMTP-11 is active in preclinical models of human osteosarcoma and a candidate targeted drug for clinical translation

Osteosarcoma occurs predominantly in children and young adults. High-grade tumors require multidisciplinary treatment consisting of chemotherapy in the neoadjuvant and adjuvant settings, along with surgical intervention. Despite this approach, death from respiratory failure secondary to the development and progression of pulmonary metastases remains a significant problem. Here, we identify the IL-11 receptor α subunit (IL-11Rα) as a cell surface marker of tumor progression that correlates with poor prognosis in patients with osteosarcoma. We also show that both IL-11Rα and its ligand, IL-11, are specifically up-regulated in human metastatic osteosarcoma cell lines; engagement of this autocrine loop leads to tumor cell proliferation, invasion, and anchorage-independent growth in vitro. Consistently, IL-11Rα promotes lung colonization by human metastatic osteosarcoma cells in vivo in an orthotopic mouse model. Finally, we evaluate the IL-11Rα-targeted proapoptotic agent bone metastasis-targeting peptidomimetic (BMTP-11) in preclinical models of primary intratibial osteosarcomas, observing marked inhibition of both tumor growth and lung metastases. This effect was enhanced when BMTP-11 was combined with the chemotherapeutic drug gemcitabine. Our combined data support the development of approaches targeting IL-11Rα, and establish BMTP-11 as a leading drug candidate for clinical translation in patients with high-risk osteosarcoma.

Endocyte slashes staff and programs

After disappointing early data on its two lead drug candidates, Endocyte is cutting 40% of its staff and paring back its development plans. Endocyte is working on small-molecule drug conjugates, which link a compound that targets a specific ligand in the body to a “payload,” often a cytotoxin that would be too toxic to be administered on its own. Weak Phase I trial data prompted Endocyte to significantly narrow the patient populations it will pursue for EC1456, a folate receptor-targeted tubulysin cancer treatment, and EC1169, a prostate-specific membrane-antigen-targeted tubulysin prostate cancer therapy.

Snapshot Profiling of the Antileishmanial Potency of Lead Compounds and Drug Candidates against Intracellular Leishmania donovani Amastigotes, with a Focus on Human-Derived Host Cells.

This study characterized the in vitro potencies of antileishmanial agents against intracellular Leishmania donovani amastigotes in primary human macrophages, obtained with or without CD14-positive monocyte enrichment, phorbol 12-myristate 13-acetate (PMA)-differentiated THP-1 cells, and mouse peritoneal exudate macrophages (PEMs). Host cell-dependent potency was confirmed for pentavalent and trivalent antimony. Fexinidazole was inactive against intracellular amastigotes across the host cell panel. Fexinidazole sulfone, (R)-PA-824, (S)-PA-824, and VL-2098 displayed similar potency in all of the host cells tested.

NS1209/SPD 502, A Novel Selective AMPA Antagonist for Stroke, Neuropathic Pain or Epilepsy? Drug Development Lessons Learned.

Preclinical Research The selective AMPA (α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid) receptor antagonist, NS1209 (also known as SPD 502) has been explored in several research and development campaigns since its selection as a lead drug candidate in the early 1990s by the Danish biotechnology company, NeuroSearch. The compound was successively tested in animal models of stroke, neuropathic pain and epilepsy. The preclinical data to support development for the treatment of stroke were incomplete, as the compound was administered after the stroke episode, and did not protect subcortical areas of the brain. Preclinical data for neuropathic pain and epilepsy appeared more promising, but the design of the Phase IIa studies in both indications was suboptimal, and an exploratory study in neuropathic pain, like one in refractory epilepsy gave inconclusive results. Preclinical data in pain models were much less convincing than reported by the authors in abstract and discussion sections. Due to a long preclinical sequential testing phase and insufficiently powered clinical trials, NS 1209 disappeared from the CNS development pipeline, while its patent protection exclusivity was markedly reduced due to the unfortunate slow speed in development-a phenomenon far from unusual in CNS drug discovery. NeuroSearch ceased operations as an R&D entity in 2012 and its R & D portfolio was transferred to Teva Pharmaceuticals and to a spin off, Saniona A/S. Based on an in-depth case analysis of the development of NS 1209, a number of recommendations are given to reduce chances of failure during clinical development of neuropathic pain compounds and, more generally, of CNS compounds. Drug Dev Res 78 : 75-80, 2017. © 2017 Wiley Periodicals, Inc.

Future Leads: Natural Products as Anti-infective Agent

Natural drugs have become a subject of world importance with both therapeutic and economic implications. Natural products are harnessed as potential therapeutic candidates from natural resources for the discovery of lead drug candidates and new pharmaceutical products. The natural products provide most of the FDA approved formulations. Thus, they are the continuous source of inspiration in the development of new drug candidates. Naturally derived products have the significant role to treat life-threatening conditions. Information collected from various database sources such as Pubmed, Scopus, ScienceDirect, Google Scholar etc. has revealed that biologically important scaffold and molecules are abundantly naturally available. Hence, the information is compiled as a short review on some highly valuable natural resources as anti-infective agents. Moreover, a special emphasis has also been laid on the marine anti-infective agents. This compilation will pave way for scientific, academic and industrial researchers to look forward to discover high valued anti-infective agents. Keywords: Natural product, drugs, anti-infective agent, marine sources, sponges, infectious diseases.

Azolium analogues as CDK4 inhibitors: Pharmacophore modeling, 3D QSAR study and new lead drug discovery

The cyclin-dependent kinase 4 (CDK4) enzyme is a key regulator in cell cycle G1 phase progression. It is often overexpressed in variety of cancer cells, which makes it an attractive therapeutic target for cancer treatment. A number of chemical scaffolds have been reported as CDK4 inhibitors in the literature, and in particular azolium scaffolds as potential inhibitors. Here, a ligand based pharmacophore modeling and an atom based 3D-QSAR analyses for a series of azolium based CDK4 inhibitors are presented. A five point pharmacophore hypothesis, i.e. APRRR with one H-bond acceptor (A), one positive cationic feature (P) and three ring aromatic sites (R) is developed, which yielded an atom based 3D-QSAR model that shows an excellent correlation coefficient value- R2 = 0.93, fisher ratio- F = 207, along with good predictive ability- Q2 = 0.79, and Pearson R value = 0.89. The visual inspection of the 3D-QSAR model, with the most active and the least active ligands, demonstrates the favorable and unfavorable structural regions for the activity towards CDK4. The roles of positively charged nitrogen, the steric effect, ligand flexibility, and the substituents on the activity are in good agreement with the previously reported experimental results. The generated 3D QSAR model is further applied as query for a 3D database screening, which identifies 23 lead drug candidates with good predicted activities and diverse scaffolds. The ADME analysis reveals that, the pharmacokinetic parameters of all the identified new leads are within the acceptable range.

Chemopreventive Potential of 2,3,5,4'-Tetrahydroxystilbene-2-O-β-D-glucoside on the Formation of Aberrant Crypt Foci in Azoxymethane-Induced Colorectal Cancer in Rats.

2,3,5,4′-Tetrahydroxystilbene-2-O-β-D-glucoside (THSG) has been shown to have antioxidative and anti-inflammatory effects. Oxidative and inflammatory reactions are related to the development of colorectal carcinoma (CRC). In the present study, we characterized the preventive activities of THSG on colon carcinogenesis using the azoxymethane- (AOM-) mediated rat colon carcinogenesis model. F344 male rats were randomly divided into 5 groups (untreated and AOM model rats treated with or without THSG at 30, 150, or 250 mg/kg) after which the numbers of aberrant crypt foci (ACF) were assessed in the colon tissues of all rats. The expressions of nuclear factor-κB (NF-κB), cyclooxygenase-2 (COX-2), matrix metalloproteinase proteins (MMPs), and carcinoembryonic antigen (CEA) were measured as effective early predictors of CRC using western blot analysis. Treatment with THSG (150 or 250 mg/kg) induced a 50% reduction in total colonic ACF formation (P < 0.05). Furthermore, our results revealed a downregulation of CEA and NF-κB protein levels in the reduced number of ACF elicited by treatment with THSG, whereas levels of COX-2 and MMPs proteins were not changed. Collectively, THSG may be a promising natural lead compound or drug candidate for treating early phases of CRC.

Vzhe-039, a Novel Structurally-Enhanced Allosteric Hemoglobin Effector Inhibits Sickling of SS Erythrocytes In Vitro, and Exhibits Improved Pharmacologic Properties In Vivo

Allosteric effectors of hemoglobin (AEH) remain promising as a viable therapeutic approach for the management of sickle cell disease (SCD). AEH bind to hemoglobin (Hb) in a transiently covalently manner, increasing Hb affinity for oxygen (O2), with concomitant inhibition of polymerization of deoxygenated sickle Hb (HbS) and erythrocyte sickling. As part of our ongoing efforts to surmount well-known AEH druggability challenges, we have designed and synthesized VZHE-039, a novel substituted benzaldehyde with potent in-vitro anti-polymerization activity, as well as more favorable in-vivopharmacokinetic and pharmacodynamic (PK/PD) properties. Here, we report the results of our early findings.The anti-sickling properties of VZHE-039 were tested in-vitro by incubating 0.5, 1, and 2 mM concentrations with blood suspensions from a subject with homozygous SCD (hematocrit: 20%) under hypoxic conditions (4% O2/96% N2) at 37°C for 2 h. At conclusion, aliquots were drawn into a fixative (2% glutaraldehyde solution), and sickling was assessed by microscopy. Aliquot samples were also subjected to cation-exchange HPLC analyses to measure the degree of Hb modification (Hb adduct formation), as well as standard O2 equilibrium curves (OEC) to assess p50 shifts. Subsequently, we conducted in-vivo PK/PD studies in wild-type mice that received single doses of VZHE-039 via the intravenous (I.V.: 25 and 50 mg/kg), intraperitoneal (I.P.: 100-150 mg/kg) and oral (P.O.: 100-200 mg/kg) routes. Serial blood samples were collected up to 24 h after I.V. and P.O., and up to 6 h after I.P. administration, respectively; aliquots were hemolyzed, de-proteinized and subjected to reverse-phase HPLC-UV assay to quantify VZH-039 blood concentrations. Residual blood samples were also hemolyzed, and clarified lysates were assayed for in-vivoHb adduct formation, and the corresponding change in Hb oxygen affinity (Δp50, %).The results of our in-vitrostudies demonstrated a concentration-dependent inhibition of SS cell sickling: 39±1.4%, 68.6±4.9%, and 89.9±5.2%, at 0.5, 1 and 2 mM of VZHE-039, respectively. HbS was modified correspondingly (46±7.4%, 83.6±6.4%, and 96.4±6.2%), and this adduct formation was correlated linearly with the left shift in OEC (Δp50 values of 34.3±8.7%, 63.6±2.4%, and 76.6±2.5%).Noncompartmental PK analysis showed that, after I.V. administration, systemic PK was dose-independent with a CLtot of 0.5 mL/min/kg, resulting in a terminal half-life of 9 h. After I.P. administration, AUCtrap increased supra-proportionally with dose; the limited sampling schedule suggested an I.P. bioavailability of >20%. After P.O. administration, AUCtrap increased supra-proportionally with dose as well due to an increase in oral bioavailability to ~ 10%, with peak blood concentrations up to ~ 0.25 mM; the terminal half-lives were prolonged (relative to I.V.) to 14 h. The PD effect-time course of change in %Hb adduct paralleled (and was reasonably linearly related to) blood concentrations for all routes. Baseline-corrected peak PD effects after I.V. administration were 15.7% and 31.9%, after 25 and 50 mg/kg respectively; after P.O. administration of 200 mg/kg, the peak change was 17.6%. Overall, VZHE-039 exhibited a low (metabolic) clearance, presumably reflecting high-affinity and sustained Hb (and possibly albumin) binding, leading to the observed extended terminal half-life and duration of action. While its oral bioavailability is low (likely due to limited GI solubility) and there is evidence of saturable first-pass effects and possibly enterohepatic recycling, oral in-vivo exposures were associated with PD effects that were consistent with the results from the in-vitrostudies.In conclusion, the results of our current studies establish VZHE-039 as a novel, potent anti-sickling agent, confirm its proposed mechanism of action in-vitro and in-vivo, and suggest that therapeutically-relevant blood concentrations may be achieved after daily oral doses. Therefore, VZHE-039 is our new lead drug candidate that may require further modifications and studies to (a) improve its GI solubility and oral bioavailability; (b) elucidate atomic level structural interactions and kinetics of its Hb binding; and (c) formally investigate its biological activity after repeat-doses in a SCD mouse model. DisclosuresNo relevant conflicts of interest to declare.

Design, synthesis and SAR analysis of potent BACE1 inhibitors: Possible lead drug candidates for Alzheimer's disease

We have identified potent isophthalic acid derivatives armed with imidazol and indolyl groups as potent β-secretase inhibitors. The most effective analogs demonstrated low nano-molar potency for the BACE1 (β-secretase cleaving enzyme) as measured by FRET (Fluorescence Resonance Energy Transfer) and cell-based (ELISA) assays. Our design strategy followed a traditional SAR approach and was supported by molecular modeling studies based on previously reported hydroxyethylene transition state inhibitor derived from isophthalic acid I. In the FRET assay, the most potent compound, 10a, displayed an IC50 value for BACE1 of 75 nM, and exhibited cellular activity with an EC50 value of 0.81 μM. On the other hand, compound 11b was found to be the most potent compound in the cell-based assay with an EC50 value of 0.29 μM.

Drug-like Properties and ADME of Xanthone Derivatives: The Antechamber of Clinical Trials.

Xanthone derivatives have been described as compounds with a privileged scaffold exhibiting diverse biological/pharmacological activities, what directed the interest to pursue the development of these derivatives into drug candidates. Nevertheless, to achieve this purpose it is crucial to study their pharmacokinetics and toxicity (PK/tox) properties as decision endpoints to continue or interrupt the development investment. This review aims to expose the most relevant analytical methods used in the physicochemical and PK/tox studies in order to detect, quantify, and identify different bioactive xanthones. Analyzing the main results from in vitro and in vivo systems towards ADME properties such as solubility, lipophilicity, pKa, chemical and metabolic stability, permeability, transporters modulation, and plasma protein binding, it is possible to uncover some threats governing the PK properties and to understand the bioavailability and drugability of xanthone derivatives. The last section of this review focuses on a case-study of the development of the drug candidate DMXAA, which has reached clinical trials, to provide the paths and the importance of PK/tox parameters of this scaffold. The data assembled in this review intends to guide for tackling issues in the design of potential lead compounds and drug candidates with a xanthone scaffold.

Talented 12 class of 2015: Where are they now?

TALENTED 12 Talented 12 class of 2015: Where are they now?Changing the world takes a while. We asked our inaugural class what they’ve been up to this past year. ShareShare onFacebookTwitterWechatLinked InRedditEmail C&EN, 2016, 94 (33), p 50August 22, 2016Cite this:C&EN 94, 33, 50Here, Erb (left) celebrates the feat with grad student Thomas Schwander. “Put your helmets on, we are going to cycle CO2!” (Credit: Erb Lab )Figure1of2Balskus, a microbial metabolism expert, poses with Hitomi Nakamura (left) and Smaranda Bodea (right). (Credit: Courtesy of Emily Balskus)Figure1of2 Brad OlsenMIT Olsen reports that his group published its first paper on loop defects in polymer networks in Physical Review Letters (DOI: 10.1103/physrevlett.116.188302). Tobias ErbMax Planck Institute for Terrestrial Microbiology Erb’s team successfully engineered enzymes to pull CO2 from the atmosphere and efficiently convert it into useful carbon-based compounds. Luke LavisHoward Hughes Medical Institute’s Janelia Research Campus “After a year of heavy traveling and writing papers, I finally got back into the lab and made some dyes with my own hands.” Matt MacDonaldAir Products & Chemicals MacDonald tells us he’s been whipping up new silicon-based compounds to build microelectronic devices with three-dimensional memory technology. Troy ListerSpero Therapeutics Lister disclosed his company’s lead drug candidate, SPR741, for the first time at a meeting in Boston. SPR741 is a molecule that disrupts the outer membrane of resistant bacteria so that antibiotics can sneak in and attack. Denis MalyshevTop secret start-up “I got a job at a biotech company that I’m super stoked about.” The firm is still in stealth mode, though, so Malyshev wouldn’t name names. Kami HullUniversity of Illinois, Urbana-Champaign Hull reports that her lab has “successfully done both directed and undirected anti-Markovnikov-selective amination” this year. (Translation for nonorganickers: They’ve achieved both tight and loose control over a reaction that adds amines to the most crowded carbon in a carbon-carbon double bond.) Hosea NelsonUCLA “My lab ran its first experiment. It worked!” Nelson says. The organic chemist adds that he also taught his first classes ever. “The second class was 100 times better than the first.” Karen HavenstriteTangible Science Havenstrite says her firm was issued two patents and received U.S. Food & Drug Administration clearance for its contact lens technology, which helps treat dry eye. Emily BalskusHarvard “I graduated my first class of Ph.D. students this year!” Jacob HookerHarvard Medical School Hooker celebrated his first graduate student getting her Ph.D. And the radiochemist will soon celebrate the birth of his second child, in mid-September. Matt KananStanford Kanan pointed us to a paper his team published in Nature on a reaction that uses simple molten salts to convert greenhouse gas CO2 into building blocks for making a type of polyester plastic (DOI: 10.1038/nature17185).

The pyrrolidinoindoline alkaloid Psm2 inhibits platelet aggregation and thrombus formation by affecting PI3K/Akt signaling.

Psm2, one of the pyrrolidinoindoline alkaloids isolated from whole Selaginella moellendorffii plants, has shown a potent antiplatelet activity. In this study, we further evaluated the antiplatelet effects of Psm2, and elucidated the underlying mechanisms. Human platelet aggregation in vitro and rat platelet aggregation ex vivo were investigated. Agonist-induced platelet aggregation was measured using a light transmission aggregometer. The antithrombotic effects of Psm2 were evaluated in arteriovenous shunt thrombosis model in rats. To elucidate the mechanisms underlying the antiplatelet activity of Psm2, ELISAs, Western blotting and molecular docking were performed. The bleeding risk of Psm2 administration was assessed in a mouse tail cutting model, and the cytotoxicity of Psm2 was measured with MTT assay in EA.hy926 cells. Psm2 dose-dependently inhibited human platelet aggregation induced by ADP, U4619, thrombin and collagen with IC50 values of 0.64, 0.37, 0.35 and 0.87 mg/mL, respectively. Psm2 (1, 3, 10 mg/kg) administered to rats significantly inhibited platelet aggregation ex vivo induced by ADP. Psm2 (1, 3, 10 mg/mL, iv) administered to rats with the A-V shunt dose-dependently decreased the thrombus formation. Psm2 inhibited platelet adhesion to fibrinogen and collagen with IC50 values of 84.5 and 96.5 mg/mL, respectively, but did not affect the binding of fibrinogen to GPIIb/IIIa. Furthermore, Psm2 inhibited AktSer473 phosphorylation, but did not affect MAPK signaling and Src kinase activation. Molecular docking showed that Psm2 bound to phosphatidylinositol 3-kinase β (PI3Kβ) with a binding free energy of -13.265 kcal/mol. In addition, Psm2 did not cause toxicity in EA.hy926 cells and produced only slight bleeding in a mouse tail cutting model. Psm2 inhibits platelet aggregation and thrombus formation by affecting PI3K/Akt signaling. Psm2 may be a lead compound or drug candidate that could be developed for the prevention or treatment of thrombotic diseases.

VC-backed Biotechnology Firms: What is Entrepreneurs’ Return?

Valuation is a highly significant process used extensively not only by start-ups seeking Venture Capital (VC) funding but also by large, established companies that are in need to set a price for an acquisition or merger. Such process becomes increasingly complex in the biotechnology sector where the realization of the true value of a firm is largely correlated with the success or failure of lead drug candidates undergoing clinical trials. In this article, the author sets up a simple long-term financial model that aims at providing an easy tool for estimating entrepreneurs’ return at exit.

Artificial Neural Network Analysis of Pharmacokinetic and Toxicity Properties of Lead Molecules for Dengue Fever, Tuberculosis and Malaria.

Poor pharmacokinetic and toxicity profiles are major reasons for the low rate of advancing lead drug candidates into efficacy studies. The In-silico prediction of primary pharmacokinetic and toxicity properties in the drug discovery and development process can be used as guidance in the design of candidates. In-silico parameters can also be used to choose suitable compounds for in-vivo testing thereby reducing the number of animals used in experiments. At the Novartis Institute for Tropical Diseases, a data set has been curated from in-house measurements in the disease areas of Dengue, Tuberculosis and Malaria. Volume of distribution, half-life, total in-vivo clearance, in-vitro human plasma protein binding and in-vivo oral bioavailability have been measured for molecules in the lead optimization stage in each of these three disease areas. Data for the inhibition of the hERG channel using the radio ligand binding dofetilide assay was determined for a set of 300 molecules in these therapeutic areas. Based on this data, Artificial Neural Networks were used to construct In-silico models for each of the properties listed above that can be used to prioritize candidates for lead optimization and to assist in selecting promising molecules for in-vivo pharmacokinetic studies.