AntiHIV Agents in Clinical Use Act at Critical Stages in the Viral Replication Cycle

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Anti-HIV Agents in Clinical Use Act at Critical
Stages in the Viral Replication Cycle
Fusion Inhibitors
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Anti-HIV Agents in Clinical Use Act at Critical
Stages in the Viral Replication Cycle
NRTIs, NNRTIs
Fusion Inhibitors
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Anti-HIV Agents in Clinical Use Act at Critical
Stages in the Viral Replication Cycle
NRTIs, NNRTIs
Protease Inhibitors
Fusion Inhibitors
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Non-Nucleoside Inhibitors of HIV-1 RT (NNRTIs)

• Chemically diverse compounds comprising over 30
  different classes
• Key component of effective combination regimens
• Bind to a common allosteric site and
  noncompetitively inhibit DNA polymerization
• Single amino acid changes in the binding pocket
  directly affect drug binding
• Computer-aided design and chemical synthesis of
  second-generation of potent NNRTIs
• Several NNRTIs are in preclinical and clinical
  development

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Advantages of Tight Binding NNRTIs

• Ability to cross membrane barriers
• Irreversibly inhibit HIV-1 RT activity
• Rapid virucidal activity without activation
• Stable under acidic thermal conditions
• Not perturb the vaginal mucosa flora
• Lack absorption to prevent drug resistance

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Composite Binding Pocket of HIV-1 RT
Yellow Polar region Blue Hydrophobic
region Red Hydrogen-bond region
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Rational Design of Thiourea NNRTIs
PETT
Trovirdine
PHI-236
PHI-346
PHI-443
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Binding Mode of Thiourea NNRTIs
PHI-236
PHI-346
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Correlation Between Lower Ludi Ki Values and
HIV-1 rRT IC50 or p24 IC50 Values for 14 Thiourea
NNRTIs
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Anti-HIV Profile of Thiourea NNRTIs
HIV-1 strain/isolate Anti-HIV activity IC50
(?M) PHI-236 PHI-443 TRV NVP DLV HTLVIIIB lt0.001
0.03 0.007 0.034 0.009 A17 (Y181C) 0.1 0.04 0.5 gt1
00 50 A17 variant (Y181CK103N) 8 3.2 gt100 gt100 gt1
00 RT-MDR (74V41L106A215Y) 0.005 0.004 0.02 5 0
.4 Primary isolates (n 23a) 0.04 0.02 ND ND ND N
RTI-resistant (n 16b) 0.009 0.03 ND ND ND
a Primary clinical isolates with 2 to 7 RT gene
mutations (K20R, M41L, E44D, D67N, T69D, T69N,
K70R, L74V, K103N, F116S, Y181C, L210W, T215S,
T215F, T215Y, K219E, K219N, K219Q). b Primary
clinical HIV-1 isolates from South America, Asia,
and sub-Saharan Africa with 2 to 7 RT gene
mutations (M41L, E44D, D67N, T69N, K70R, K103N,
Y181C, L210W, T215Y, K219N).
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Ternary Phase Diagram of Microemulsion-based
Vaginal Drug Delivery System
36 Cremophor EL 24 Phospholipon 90G 20
Propylene glycol 20 PEG 200
Water
Captex 300
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Thiourea NNRTIs Protect SCID Mice from Vaginal
HIV-1 Infection
Pretreatment Infected () Survival () RNA
(cps/ml) P-value PHI-236 (Ex Vivo)
Vehicle 9/10 (90) 100 14,755 1000 nM 1/10
(10) 100 3,100 0.001 2000 nM 0/10
(0) 100 NA 0.0001 PHI-346 (Ex Vivo) 2000
nM 4/10 (40) 100 6,050 0.05 2000 ?M 2/10
(20) 100 2,800 0.005 PHI-346 (In Vivo)
0.5 gel 1/10 (10) 100 (34,000) 0.001 1.0
gel 0/10 (0) 100 NA 0.0001 PHI-443 (Ex Vivo)
Vehicle 5/10 (50) 100 6260 2000 nM 0/7
(0) 100 NA 0.04
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Preclinical Development of Thiourea NNRTIs
MUCOSAL TOXICITY (0.5, 1, 2 gel) Rabbit
14-day vaginal irritation study (5/gp) No
adverse effects Porcine 4-day vaginal irritation
study (3/gp) No adverse effects Human
ecto/endo/vaginal epithelial cell viability Non
cytotoxic SUBCHRONIC TOXICITY (3 doses) Mouse
(13-wk) intravaginal exposure (30/gp) No
adverse effects REPRODUCTIVE TOXICOLOGY (3
doses) Mouse (13-wk) fertility pup development
(20/gp) No adverse effects Rabbit fertility
pup development (20/gp) No adverse
effects CONTRACEPTIVE ACTIVITY (2 gel) PHI-346
vaginal challenge, rabbit (20/gp) Significant
protection PHI-443 vaginal challenge, rabbit
(40/gp) Non-contraceptive MICROBICIDE ACTIVITY
(ex vivo in vivo) Single vaginal challenge,
SCID mice (10/gp) Significant
protection PHARMACOKINETIC/TOXICITY (dose range
40-400 mg/kg) Mouse intravenous
intraperitoneal challenge Favorable
(gt40) Mouse oral challenge Minimal absorption
(lt2)
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CONCLUSIONS

• Rationally designed thiourea NNRTIs deduced from
  changes in binding pocket size, shape, and
  residue character display potent anti-HIV
  activity
• Thiourea NNRTIs are more potent against
  drug-sensitive multidrug-resistant strains of
  HIV-1 than the three classes of NNRTIs in
  clinical use
• Thiourea NNRTIs are stable, retain antiviral
  activity, and lack systemic or mucosal toxicity
• Thiourea NNRTIs are useful as topical virucides
  to prevent the sexual transmission of HIV

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Anti-HIV Agents in Clinical Use Act at Critical
Stages in the Viral Replication Cycle