Effect of a high-fat meal on the relative bioavailability of H3B-6527, a novel FGFR4 inhibitor, in healthy volunteers.

PURPOSE: This Phase I study estimated the effect of a high-fat meal on the pharmacokinetics (PK) of H3B-6527, a covalent inhibitor of the fibroblast growth factor receptor (FGFR) 4 in clinical development for hepatocellular carcinoma and intrahepatic cholangiocarcinoma. METHODS: In this randomized, single center, single-dose, open-label, 2-period crossover study 12 healthy male volunteers, aged 18-55 years old, received a single 200-mg dose of H3B-6527 (capsule) following an overnight fast or a high-fat breakfast. PK samples were collected serially up to 36 h postdose. H3B-6527 concentrations were measured using a validated high-performance liquid chromatography tandem mass spectrometry method. PK data were analyzed using a noncompartmental approach based on a mixed-effects model. The safety and tolerability of H3B-6527 were also assessed. RESULTS: H3B-6527 plasma exposure increased after a high-fat meal with fed/fasted ratios of the geometric means (90% confidence interval) of 174% (102-298%) for Cmax and 246% (146-415%) for AUC0-t. Food delayed and prolonged absorption of H3B-6527, with a fed/fasted ratio for tmax of 200% (137-263%). PK variability was lower under the fed condition, as illustrated by the CV% for Cmax and AUC0-t of 41.9-54.5% (fed) versus 64.3-70.4% (fasted). CONCLUSIONS: A single 200 mg dose of H3B-6527 was safe and generally well tolerated when administered to healthy adult males. A high-fat meal significantly increased exposure to H3B-6527, from 1.5- to 2.5-fold in the systemic circulation, compared to administration under fasted conditions. Food delayed and prolonged absorption of H3B-6527. In general, lower inter-subject variability was observed in the fed state in healthy volunteers. TRIAL REGISTRATION: ClinicalTrials.gov.: NCT03424577.

Structure-activity relationship of the aminomethylcyclines and the discovery of omadacycline.

A series of novel tetracycline derivatives were synthesized with the goal of creating new antibiotics that would be unaffected by the known tetracycline resistance mechanisms. New C-9-position derivatives of minocycline (the aminomethylcyclines [AMCs]) were tested for in vitro activity against Gram-positive strains containing known tetracycline resistance mechanisms of ribosomal protection (Tet M in Staphylococcus aureus, Enterococcus faecalis, and Streptococcus pneumoniae) and efflux (Tet K in S. aureus and Tet L in E. faecalis). A number of aminomethylcyclines with potent in vitro activity (MIC range of ≤0.06 to 2.0 µg/ml) were identified. These novel tetracyclines were more active against one or more of the resistant strains than the reference antibiotics tested (MIC range, 16 to 64 µg/ml). The AMC derivatives were active against bacteria resistant to tetracycline by both efflux and ribosomal protection mechanisms. This study identified the AMCs as a novel class of antibiotics evolved from tetracycline that exhibit potent activity in vitro against tetracycline-resistant Gram-positive bacteria, including pathogenic strains of methicillin-resistant S. aureus (MRSA) and vancomycin-resistant enterococci (VRE). One derivative, 9-neopentylaminomethylminocycline (generic name omadacycline), was identified and is currently in human trials for acute bacterial skin and skin structure infections (ABSSSI) and community-acquired bacterial pneumonia (CABP).

Probing the specificity of gamma-glutamylamine cyclotransferase: an enzyme involved in the metabolism of transglutaminase-catalyzed protein crosslinks.

γ-Glutamylamine cyclotransferase (gGACT) catalyzes the intramolecular cyclization of a variety of L-γ-glutamylamines producing 5-oxo-L-proline and free amines. Its substrate specificity implicates it in the downstream metabolism of transglutaminase products, and is distinct from that of γ-glutamyl cyclotransferase which acts on L-γ-glutamyl amino acids. To elucidate the mechanism by which gGACT distinguishes between L-γ-glutamylamine and amino acid substrates, the specificity of the rabbit kidney enzyme for the amide region of substrates was probed through the kinetic analysis of a series of L-γ-glutamylamines. The isodipeptide N(ε)-(L-γ-glutamyl)-L-lysine 1 was used as a reference. The kinetic constants of the L-γ-glutamyl derivative of n-butylamine 7, were nearly identical to those of 1. Introduction of a methyl or carboxylate group on the carbon adjacent to the side-chain amide nitrogen in L-γ-glutamylamine substrates resulted in a dramatic decrease in substrate properties for gGACT thus providing an explanation of why gGACT does not act on L-γ-glutamyl amino acids except for L-γ-glutamylglycine. Placement of substituents on carbons further removed from the side-chain amide nitrogen in L-γ-glutamylamines restored activity for gGACT, and L-γ-glutamylneohexylamine 19 had a higher specificity constant (k(cat) /K(m)) than 1. gGACT did not exhibit any stereospecificity in the amide region of L-γ-glutamylamine substrates. In addition, analogues (26-30) with heteroatom substitutions for the γ methylene position of the L-γ-glutamyl moiety were examined. Several thiocarbamoyl derivatives of L-cysteine (28-30) were excellent substrates for gGACT.

Tetracyclines that promote SMN2 exon 7 splicing as therapeutics for spinal muscular atrophy.

There is at present no cure or effective therapy for spinal muscular atrophy (SMA), a neurodegenerative disease that is the leading genetic cause of infant mortality. SMA usually results from loss of the SMN1 (survival of motor neuron 1) gene, which leads to selective motor neuron degeneration. SMN2 is nearly identical to SMN1 but has a nucleotide replacement that causes exon 7 skipping, resulting in a truncated, unstable version of the SMA protein. SMN2 is present in all SMA patients, and correcting SMN2 splicing is a promising approach for SMA therapy. We identified a tetracycline-like compound, PTK-SMA1, which stimulates exon 7 splicing and increases SMN protein levels in vitro and in vivo in mice. Unlike previously identified molecules that stimulate SMN production via SMN2 promoter activation or undefined mechanisms, PTK-SMA1 is a unique therapeutic candidate in that it acts by directly stimulating splicing of exon 7. Synthetic small-molecule compounds such as PTK-SMA1 offer an alternative to antisense oligonucleotide therapies that are being developed as therapeutics for a number of disease-associated splicing defects.

Novel anti-infection agents: small-molecule inhibitors of bacterial transcription factors.

Structure-based drug design was utilized to identify potent small-molecule inhibitors of proteins within the AraC family of bacterial transcription factors, which control virulence in medically important microbes. These agents represent a novel approach to fight infectious disease and may be less likely to promote resistance development. These compounds lack intrinsic antibacterial activity in vitro and were able to limit a bacterial infection in a mouse model of urinary tract infection.