An oral SARS-CoV-2 M inhibitor clinical candidate for the treatment of COVID-19.

The worldwide outbreak of COVID-19 caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has become a global pandemic. Alongside vaccines, antiviral therapeutics are an important part of the healthcare response to countering the ongoing threat presented by COVID-19. Here, we report the discovery and characterization of PF-07321332, an orally bioavailable SARS-CoV-2 main protease inhibitor with in vitro pan-human coronavirus antiviral activity and excellent off-target selectivity and in vivo safety profiles.

Can We Create an Arteriovenous Fistula for Hemodialysis through 0.5-1.0 cm Incision without Using Vascular Clamps?

A native arteriovenous fistula (AVF) is a gold standard for renal replacement therapy, where regular hemodialysis is the mainstay of survival in the majority of patients suffering from end-stage renal disease. Appropriate vascular clamps are routinely used to occlude an artery and a vein before an arteriotomy or a venotomy is done to prevent blood loss and have a clear field and an ease of anastomosis. The title makes one wonder, is it then possible to create an AVF without using vascular clamps? And through incisions as small as 0.

Dissecting the molecular determinants of clinical PARP1 inhibitor selectivity for tankyrase1.

Poly-ADP-ribosyltransferases play a critical role in DNA repair and cell death, and poly(ADP-ribosyl) polymerase 1 (PARP1) is a particularly important therapeutic target for the treatment of breast cancer because of its synthetic lethal relationship with breast cancer susceptibility proteins 1 and 2. Numerous PARP1 inhibitors have been developed, and their efficacy in cancer treatment is attributed to both the inhibition of enzymatic activity and their ability to trap PARP1 on to the damaged DNA, which is cytotoxic. Of the clinical PARP inhibitors, talazoparib is the most effective at trapping PARP1 on damaged DNA.

Discovery of Ketone-Based Covalent Inhibitors of Coronavirus 3CL Proteases for the Potential Therapeutic Treatment of COVID-19.

The novel coronavirus disease COVID-19 that emerged in 2019 is caused by the virus SARS CoV-2 and named for its close genetic similarity to SARS CoV-1 that caused severe acute respiratory syndrome (SARS) in 2002. Both SARS coronavirus genomes encode two overlapping large polyproteins, which are cleaved at specific sites by a 3C-like cysteine protease (3CL) in a post-translational processing step that is critical for coronavirus replication. The 3CL sequences for CoV-1 and CoV-2 viruses are 100% identical in the catalytic domain that carries out protein cleavage.

Small molecule inhibitors reveal PTK6 kinase is not an oncogenic driver in breast cancers.

Protein tyrosine kinase 6 (PTK6, or BRK) is aberrantly expressed in breast cancers, and emerging as an oncogene that promotes tumor cell proliferation, migration and evasion. Both kinase-dependent and -independent functions of PTK6 in driving tumor growth have been described, therefore targeting PTK6 kinase activity by small molecule inhibitors as a therapeutic approach to treat cancers remains to be validated. In this study, we identified novel, potent and selective PTK6 kinase inhibitors as a means to investigate the role of PTK6 kinase activity in breast tumorigenesis.

Optimization of Orally Bioavailable Enhancer of Zeste Homolog 2 (EZH2) Inhibitors Using Ligand and Property-Based Design Strategies: Identification of Development Candidate (R)-5,8-Dichloro-7-(methoxy(oxetan-3-yl)methyl)-2-((4-methoxy-6-methyl-2-oxo-1,2-dihydropyridin-3-yl)methyl)-3,4-dihydroisoquinolin-1(2H)-one (PF-06821497).

A new series of lactam-derived EZH2 inhibitors was designed via ligand-based and physicochemical-property-based strategies to address metabolic stability and thermodynamic solubility issues associated with previous lead compound 1. The new inhibitors incorporated an sp hybridized carbon atom at the 7-position of the lactam moiety present in lead compound 1 as a replacement for a dimethylisoxazole group. This transformation enabled optimization of the physicochemical properties and potency compared to compound 1.

Conserved RNA-binding specificity of polycomb repressive complex 2 is achieved by dispersed amino acid patches in EZH2.

Polycomb repressive complex 2 (PRC2) is a key chromatin modifier responsible for methylation of lysine 27 in histone H3. PRC2 has been shown to interact with thousands of RNA species in vivo, but understanding the physiological function of RNA binding has been hampered by the lack of separation-of-function mutants. Here, we use comprehensive mutagenesis and hydrogen deuterium exchange mass spectrometry (HDX-MS) to identify critical residues for RNA interaction in PRC2 core complexes from and , for which crystal structures are known.

Proteome-wide Map of Targets of T790M-EGFR-Directed Covalent Inhibitors.

Patients with non-small cell lung cancers that have kinase-activating epidermal growth factor receptor (EGFR) mutations are highly responsive to first- and second-generation EGFR inhibitors. However, these patients often relapse due to a secondary, drug-resistant mutation in EGFR whereby the gatekeeper threonine is converted to methionine (T790M). Several third-generation EGFR inhibitors have been developed that irreversibly inactivate T790M-EGFR while sparing wild-type EGFR, thus reducing epithelium-based toxicities.

The Axl kinase domain in complex with a macrocyclic inhibitor offers first structural insights into an active TAM receptor kinase.

The receptor tyrosine kinase family consisting of Tyro3, Axl, and Mer (TAM) is one of the most recently identified receptor tyrosine kinase families. TAM receptors are up-regulated postnatally and maintained at high levels in adults. They all play an important role in immunity, but Axl has also been implicated in cancer and therefore is a target in the discovery and development of novel therapeutics.

Discovery of N-((3R,4R)-4-Fluoro-1-(6-((3-methoxy-1-methyl-1H-pyrazol-4-yl)amino)-9-methyl-9H-purin-2-yl)pyrrolidine-3-yl)acrylamide (PF-06747775) through Structure-Based Drug Design: A High Affinity Irreversible Inhibitor Targeting Oncogenic EGFR Mutants with Selectivity over Wild-Type EGFR.

Mutant epidermal growth factor receptor (EGFR) is a major driver of non-small-cell lung cancer (NSCLC). Marketed first generation inhibitors, such as erlotinib, effect a transient beneficial response in EGFR mutant NSCLC patients before resistance mechanisms render these inhibitors ineffective. Secondary oncogenic EGFR mutations account for approximately 50% of relapses, the most common being the gatekeeper T790M substitution that renders existing therapies ineffective.

Turned in fasciocutaneous island flap from face and neck based on subdermal microcirculation for reconstruction of the oral cavity following cancer surgery.

Background: The skin and soft tissues of the face and neck have a rich plexus of dermal-subdermal vessels, which creates the possibility of raising a fasciocutaneous flap based on this vascular supply. A turned in fasciocutaneous island flap (TIFCIF) from an adjacent area of the defect can provide a simple substitute to many complex reconstructive procedures.

Materials And Methods: Fifteen patients underwent wide excision for oral cancer and upper neck dissection, maintaining bone framework, between August 2010 and June 2014.

Broad-Spectrum Kinase Profiling in Live Cells with Lysine-Targeted Sulfonyl Fluoride Probes.

Protein kinases comprise a large family of structurally related enzymes. A major goal in kinase-inhibitor development is to selectively engage the desired kinase while avoiding myriad off-target kinases. However, quantifying inhibitor interactions with multiple endogenous kinases in live cells remains an unmet challenge.

Polycomb repressive complex 2 structure with inhibitor reveals a mechanism of activation and drug resistance.

Polycomb repressive complex 2 (PRC2) mediates gene silencing through chromatin reorganization by methylation of histone H3 lysine 27 (H3K27). Overexpression of the complex and point mutations in the individual subunits of PRC2 have been shown to contribute to tumorigenesis. Several inhibitors of the PRC2 activity have shown efficacy in EZH2-mutated lymphomas and are currently in clinical development, although the molecular basis of inhibitor recognition remains unknown.

Discovery of 1-{(3R,4R)-3-[({5-Chloro-2-[(1-methyl-1H-pyrazol-4-yl)amino]-7H-pyrrolo[2,3-d]pyrimidin-4-yl}oxy)methyl]-4-methoxypyrrolidin-1-yl}prop-2-en-1-one (PF-06459988), a Potent, WT Sparing, Irreversible Inhibitor of T790M-Containing EGFR Mutants.

First generation EGFR TKIs (gefitinib, erlotinib) provide significant clinical benefit for NSCLC cancer patients with oncogenic EGFR mutations. Ultimately, these patients' disease progresses, often driven by a second-site mutation in the EGFR kinase domain (T790M). Another liability of the first generation drugs is severe adverse events driven by inhibition of WT EGFR.

Effect of water solvation on the lipophilicity of isomeric pyrimidine-carboxamides.

Incorporation of nitrogen is a common medicinal chemistry tactic to reduce logD values. Neighboring group participation influences logD, so the results are isomer dependent. The logD and logP differences observed between isomeric pyrimidines 1, 2 and 3 presumably result when the carbonyl or ether lone pairs are in close proximity to a heterocyclic nitrogen lone pair, recruiting water to bridge between the electron rich atoms.

SAH derived potent and selective EZH2 inhibitors.

A series of novel enhancer of zeste homolog 2 (EZH2) inhibitors was designed based on the chemical structure of the histone methyltransferase (HMT) inhibitor SAH (S-adenosyl-l-homocysteine). These nucleoside-based EZH2 inhibitors blocked the methylation of nucleosomes at H3K27 in biochemical assays employing both WT PRC2 complex as well as a Y641N mutant PRC2 complex. The most potent compound, 27, displayed IC50's against both complexes of 270 nM and 70 nM, respectively.

Contribution of hydrogen bonds to protein stability.

Our goal was to gain a better understanding of the contribution of the burial of polar groups and their hydrogen bonds to the conformational stability of proteins. We measured the change in stability, Δ(ΔG), for a series of hydrogen bonding mutants in four proteins: villin headpiece subdomain (VHP) containing 36 residues, a surface protein from Borrelia burgdorferi (VlsE) containing 341 residues, and two proteins previously studied in our laboratory, ribonucleases Sa (RNase Sa) and T1 (RNase T1). Crystal structures were determined for three of the hydrogen bonding mutants of RNase Sa: S24A, Y51F, and T95A.

Pyrimidone-based series of glucokinase activators with alternative donor-acceptor motif.

Glucokinase activators are a class of experimental agents under investigation as a therapy for Type 2 diabetes mellitus. An X-ray crystal structure of a modestly potent agent revealed the potential to substitute the common heterocyclic amide donor-acceptor motif for a pyridone moiety. We have successfully demonstrated that both pyridone and pyrimidone heterocycles can be used as a potent donor-acceptor substituent.

EGFR: tale of the C-terminal tail.

The carboxy terminal tail of epidermal growth factor receptor (EGFR) plays a critical role in the regulation of the enzyme activity of the kinase. There is a good structural model for the mechanism by which the C-terminal tail proximal to the kinase domain contributes to the negative regulation of the activity. Its conformation in the active state, conversely, has remained elusive due to its dynamic nature.

Biaxial serial excision: A technique to deal with benign skin lesions and scars.

Background: In the best of hands, the ultimate surgical scar of an otherwise well-performed surgery is unpredictable, and surgical techniques are constantly evolving to prevent or revise large scars. The present series uses the principles of serial excision to reduce the eventual scar length.

Materials And Methods: Between January 1991 and December 2010, 30 patients were operated upon.

Ack1: activation and regulation by allostery.

The non-receptor tyrosine kinase Ack1 belongs to a unique multi-domain protein kinase family, Ack. Ack is the only family of SH3 domain containing kinases to have an SH3 domain following the kinase domain; others have their SH3 domains preceding the kinase domain. Previous reports have suggested that Ack1 does not require phosphorylation for activation and the enzyme activity of the isolated kinase domain is low relative to other kinases.

Insights into the aberrant activity of mutant EGFR kinase domain and drug recognition.

The oncogenicity of the L858R mutant form of the epidermal growth factor receptor (EGFR) in non-small-cell lung cancer is thought to be due to the constitutive activation of its kinase domain. The selectivity of the marketed drugs gefitinib and erlotinib for L858R mutant is attributed to their specific recognition of the active kinase and to weaker ATP binding by L858R EGFR. We present crystal structures showing that neither L858R nor the drug-resistant L858R+T790M EGFR kinase domain is in the constitutively active conformation.

Specific inhibition of Notch1 signaling enhances the antitumor efficacy of chemotherapy in triple negative breast cancer through reduction of cancer stem cells.

Recent evidence suggests that Notch signaling may play a role in regulation of cancer stem cell (CSC) self-renewal and differentiation hence presenting a promising target for development of novel therapies for aggressive cancers such as triple negative breast cancer (TNBC). We generated Notch1 monoclonal antibodies (mAbs) that specifically bind to the negative regulatory region of human Notch1. Notch1 inhibition in TNBC Sum149 and patient derived xenograft (PDX) 144580 models led to significant TGI particularly in combination with docetaxel.

Design strategies to target crystallographic waters applied to the Hsp90 molecular chaperone.

A series of novel and potent small molecule Hsp90 inhibitors was optimized using X-ray crystal structures. These compounds bind in a deep pocket of the Hsp90 enzyme that is partially comprised by residues Asn51 and Ser52. Displacement of several water molecules observed crystallographically in this pocket using rule-based strategies led to significant improvements in inhibitor potency.

Optimization of potent, selective, and orally bioavailable pyrrolodinopyrimidine-containing inhibitors of heat shock protein 90. Identification of development candidate 2-amino-4-{4-chloro-2-[2-(4-fluoro-1H-pyrazol-1-yl)ethoxy]-6-methylphenyl}-N-(2,2-difluoropropyl)-5,7-dihydro-6H-pyrrolo[3,4-d]pyrimidine-6-carboxamide.

A novel class of heat shock protein 90 (Hsp90) inhibitors was discovered by high-throughput screening and was subsequently optimized using a combination of structure-based design, parallel synthesis, and the application of medicinal chemistry principles. Through this process, the biochemical and cell-based potency of the original HTS lead were substantially improved along with the corresponding metabolic stability properties. These efforts culminated with the identification of a development candidate (compound 42) which displayed desired PK/PD relationships, significant efficacy in a melanoma A2058 xenograft tumor model, and attractive DMPK profiles.