New developments in anti-HIV chemotherapy.
Virtually all the compounds that are currently used, or are subject of advanced clinical trials, for the treatment of human immunodeficiency virus (HIV) infections, belong to one of the following classes: (i) nucleoside/nucleotide reverse transcriptase inhibitors (NRTIs): i.e. zidovudine (AZT), didanosine (ddI), zalcitabine (ddC), stavudine (d4T), lamivudine (3TC), abacavir (ABC), emtricitabine [(-)FTC], tenofovir disoproxil fumarate; (ii) non-nucleoside reverse transcriptase inhibitors (NNRTIs): i.e. nevirapine, delavirdine, efavirenz, emivirine; and (iii) protease inhibitors (PIs): i.e. saquinavir, ritonavir, indinavir, nelfinavir, amprenavir and lopinavir. In addition to the reverse transcriptase (RT) and protease reaction, various other events in the HIV replicative cycle can be considered as potential targets for chemotherapeutic intervention: (i) viral adsorption, through binding to the viral envelope glycoprotein gp120 (polysulfates, polysulfonates, polycarboxylates, polyoxometalates, polynucleotides, and negatively charged albumins); (ii) viral entry, through blockade of the viral coreceptors CXCR4 [bicyclam (AMD3100) derivatives] and CCR5 (TAK-779 derivatives); (iii) virus-cell fusion, through binding to the viral envelope glycoprotein gp41 (T-20, T-1249); (iv) viral assembly and disassembly, through NCp7 zinc finger-targeted agents [2,2'-dithiobisbenzamides (DIBAs), azadicarbonamide (ADA)]; (v) proviral DNA integration, through integrase inhibitors such as 4-aryl-2,4-dioxobutanoic acid derivatives; (vi) viral mRNA transcription, through inhibitors of the transcription (transactivation) process (flavopiridol, fluoroquinolones). Also, various new NRTIs, NNRTIs and PIs have been developed that possess, respectively: (i) improved metabolic characteristics (i.e. phosphoramidate and cyclosaligenyl pronucleotides by-passing the first phosphorylation step of the NRTIs), (ii) increased activity ["second" or "third" generation NNRTIs (i.e. TMC-125, DPC-083)] against those HIV strains that are resistant to the "first" generation NNRTIs, or (iii) as in the case of PIs, a different, nonpeptidic scaffold [i.e. cyclic urea (mozenavir), 4-hydroxy-2-pyrone (tipranavir)]. Nonpeptidic PIs may be expected to inhibit HIV mutant strains that have become resistant to peptidomimetic PIs. Given the multitude of molecular targets with which anti-HIV agents can interact, one should be cautious in extrapolating the mode of action of these agents from cell-free enzymatic assays to intact cells. Two examples in point are L-chicoric acid and the nonapeptoid CGP64222, which were initially described as an integrase inhibitor or Tat antagonist, respectively, but later shown to primarily act as virus adsorption/entry inhibitors, the latter through blockade of CXCR4.
De Clercq
Erik
E
Rega Institute for Medical Research, Katholieke Universiteit Leuven, Minderbroedersstraat 10, Leuven, Belgium. erik.decercq@rega.kuleuven.ac.be
D019380:Anti-HIV Agents / Q000737:chemistry* / Q000494:pharmacology*; D001665:Binding Sites; D002213:Capsid / Q000187:drug effects; D036022:Capsid Proteins; D015195:Drug Design; D015683:Gene Products, gag / Q000187:drug effects; D006678:HIV / Q000187:drug effects* / Q000235:genetics / Q000502:physiology; D015699:HIV Envelope Protein gp120 / Q000187:drug effects; D015700:HIV Envelope Protein gp41 / Q000187:drug effects; D015658:HIV Infections / Q000188:drug therapy*; D019428:HIV Integrase Inhibitors / Q000737:chemistry / Q000494:pharmacology; D017320:HIV Protease Inhibitors / Q000737:chemistry / Q000494:pharmacology; D006801:Humans; D015394:Molecular Structure; D015728:Receptors, HIV / Q000037:antagonists & inhibitors; D018894:Reverse Transcriptase Inhibitors / Q000737:chemistry / Q000494:pharmacology; D015533:Transcriptional Activation / Q000187:drug effects; D014764:Viral Proteins; D054301:gag Gene Products, Human Immunodeficiency Virus
D019380:Anti-HIV Agents; D036022:Capsid Proteins; D015683:Gene Products, gag; D015699:HIV Envelope Protein gp120; D015700:HIV Envelope Protein gp41; D019428:HIV Integrase Inhibitors; D017320:HIV Protease Inhibitors; C071884:NCP7 protein, Human immunodeficiency virus 1; D015728:Receptors, HIV; D018894:Reverse Transcriptase Inhibitors; D014764:Viral Proteins; D054301:gag Gene Products, Human Immunodeficiency Virus