1.Guanosine analog in the pyrido[2,3-d]pyrimidine ring system as a potential toll-like receptor agonist.
Jin G1, Wu CC, Carson DA, Cottam HB. Nucleosides Nucleotides Nucleic Acids. 2006;25(12):1391-7.
The synthesis of a guanosine analog in the pyrido[2,3-d]pyrimidine ring system has been accomplished by glycosylation of the preformed aromatic heterocyclic base, which was prepared in 2 steps by condensation of methyl acrylate with guanidine carbonate and methyl cyanoacetate in the presence of sodium methoxide, followed by dehydrogenation. The analog was evaluated in vitro for its ability to modulate the innate immune response by acting as an agonist or as an antagonist of Toll-like receptor (TLR) signaling by measuring cytokine induction or inhibition of induction, respectively, in mouse bone marrow-derived macrophages. Despite its structural similarity to 7-thia-8-oxoguanosine, a known TLR7 agonist, the analog was found to antagonize TLR7-induced cytokine induction in this cell-based assay.
2.Isatoribine, an agonist of TLR7, reduces plasma virus concentration in chronic hepatitis C infection.
Horsmans Y1, Berg T, Desager JP, Mueller T, Schott E, Fletcher SP, Steffy KR, Bauman LA, Kerr BM, Averett DR. Hepatology. 2005 Sep;42(3):724-31.
Immune-based therapy is the mainstay treatment for chronic hepatitis C virus (HCV) infection but causes multiple side effects and achieves durable viral clearance in only approximately 50% of patients. Most new investigational anti-HCV compounds are direct-acting antivirals for which durability of response and risk of viral mutations and resistance are not yet known. Therefore, continuing discovery and development of new immune-based treatments is desirable. Toll-like receptors (TLRs) are pathogen recognition receptors that initiate the innate immune response. The responsiveness of HCV or other ongoing chronic systemic infections to treatment with a selective TLR agonist has not been reported. Isatoribine is a selective agonist of TLR7. In a proof-of-concept study, we found that once-daily 7-day treatment with intravenous isatoribine 800 mg caused a significant (P = .001) reduction of plasma HCV RNA (mean, -0.76; range, -2.85 to +0.21 log(10) units) in otherwise untreated patients (n = 12) who were chronically infected with HCV.
3.Gateways to clinical trials.
Bayes M1, Rabasseda X, Prous JR. Methods Find Exp Clin Pharmacol. 2005 Nov;27(9):665-77.
Gateways to Clinical Trials are a guide to the most recent clinical trials in current literature and congresses. The data in the following tables have been retrieved from the Clinical Trials Knowledge Area of Prous Science Integrity(R), the drug discovery and development portal, http://integrity.prous.com. This issue focuses on the following selection of drugs: (Z)-4-Hydroxytamoxifen, [18F]-FPS; Adalimumab, alefacept, alemtuzumab, alfimeprase, aprepitant, aripiprazole, atomoxetine hydrochloride; Belatacept, bortezomib; C340, caspofungin acetate, clazosentan sodium, Cypher; Darbepoetin alfa, DB-289, decitabine, dronedarone hydrochloride, duloxetine hydrochloride; Eletriptan, entecavir, ertapenem sodium, escitalopram oxalate, eszopiclone, etoricoxib; Gaboxadol, gadofosveset sodium, galiximab, gemifloxacin mesilate, glutamine; Human insulin; I-131 ch-TNT-1/B, indiplon, inhaled insulin, isatoribine; L-Arginine hydrochloride, liposomal doxorubicin, lopinavir/ritonavir, lumiracoxib; Magnesium sulfate; Natalizumab; Olmesartan medoxomil, omapatrilat, OncoVEX (GM-CSF); rDNA insulin, rupatadine fumarate; Sorafenib; Tadalafil, teduglutide, temsirolimus, tenofovir disoproxil fumarate, tiotropium bromide; Valdecoxib, vardenafil hydrochloride hydrate.
4.Masked oral prodrugs of toll-like receptor 7 agonists: a new approach for the treatment of infectious disease.
Fletcher S1, Steffy K, Averett D. Curr Opin Investig Drugs. 2006 Aug;7(8):702-8.
Toll-like receptor (TLR)7 is a pattern-recognition receptor that activates the innate immune response. Stimulation of TLR7 induces type I interferons, pro-inflammatory cytokines, the upregulation of co-stimulatory molecules and leads to the development of an adaptive immune response. Small-molecule TLR7 agonists with broad-spectrum antiviral activities in animal models have been identified. Such compounds have been examined clinically for a number of different infectious disease indications, leading to marketing approval of one of these agents, imiquimod, for the topical treatment of external genital and perianal papillomavirus infections. In contrast with topical and intravenous routes of administration, compounds delivered orally have exhibited poor tolerability at desired doses, with substantial adverse events associated with gastrointestinal toxicity. However, dosing with masked oral prodrugs of TLR7 agonists, such as ANA-975, limits the adverse events associated with the activation of responsive gastrointestinal immune tissue.