Transcript From Natural Product to clinical trial

From Natural Product to Clinical Trials:
Bevirimat, a Plant-Derived Anti-AIDS Drug
천연물약품화학연구실
석 사
1 기
장
성
완
Index
0. AIDS
1. Introduction
2. Bioactivity-directed Fractionation and Isolation
3. Lead Identification
4. Lead Optimisation and SAR Study
4.1 Modification of the BA Triterpene Skeletion
4.2 Modification on C-3 Position of BA
4.3 Introduction of C-28 Side Chain into BA
4.4 Bifunctional BA Analouges – Potential for Maturation Inhibitor Development
5. Mechanism of Action Studies of Bevirimat
6. Preclinical Studies of Bevirimat
7. Clinical Trials and Current Status of Bevirimat
8. Conclusions
0. AIDS
ⅰ. What is the AIDS
ⅱ. Classification of HIV
ⅲ. HIV Life Cycle
ⅳ. Current status ; Anti-HIV Drug
ⅴ. Domestic research trend
ⅰ. What is the AIDS
 AIDS - Acquired Immune Deficiency Syndrome
 the human
immune system
caused by infection
with human
immunodeficiency
virus (HIV).
ⅱ. Classification of HIV
Species
HIV-1
HIV-2
Virulence
High
Lower
Infectivity
High
Low
HIV-1
Prevalence
Global
West Africa
Group : Group Ⅵ(ssRNA-RT)
Inferred
Origin
Common
chimpanzee
Sooty
Mangabey
Family : Retrociridae
Genus : Lentivirus
ⅲ. HIV Life Cycle
1
2
1. Binding
2. Reverse Transcription
3
4
3. Integration
4. Transcription
5. Translation
5
6. Viral Assembly and
6
Maturation
1. Binding
-
HIV binding T4-cell’s CD4+ receptor
-
CD4+ receptor be generated HIV binding
-
This step can be blocked by entry
inhibitors
2. Reverse Transcription
-
Making proviral DNA by RTase
-
This step can be blocked by
NRTIs(Nucleoside Reverse
Transcripatase Inhibitors) and NNRTIs
(Non-Nucleoside Reverse Transcriptase
Inhibitors)
3. Integration
-
another viral enzyme called integrase
hides the proviral DNA into the cell's DNA
-
This step can be blocked by intergrase
inhibitors
4. Transcription
-
creating a complementary strand of
genetic material called messenger RNA
or mRNA
-
This step can be blocked by antisense
antivirals or transcription inhibitors (TIs),
5. Translation
-
The mRNA carries instructions for making
new viral proteins from the nucleus
6. Viral Assembly and Maturation
-Final step virus infection
-Viral Assembly step can be blocked by
Protease Inhibitors (PIs)
-Maturation step can be blocked by
Maturation Inhibitors(Mis)
ⅳ. Current status ; Anti-HIV Drug
ⅳ. Current status ; Anti-HIV Drug
ⅴ. Domestic research trend
 Patent
- 태림제약 anti-virus drug
 Raw matrial supply
- 유한양행 GWM사와 계약
 Technology Licensing
- 화학硏 - Gilead
1. Introduction
 29 approved drugs marketed to treat HIV-1 infection
ex) Fuzeon [enfuvirtide,ENF,T-20] – inhibit viral entry
Selzentry[maraviroc,MVC] - CCR5 coreceptor antagonist
 HAART(Highly active antiretroviral therapy)
combination of drugs with different targets
HAART improved patient’s life quality and length
 But HAART made drug-resistant virus
up to 78% if HIV-1-infected individuals harbour drug-resistance virus
with a rapidly growing subgroup
 Therefore, novel potent antiviral agents need
2. Bioactivity-directed Fractionation and Isolation
QSAR(Qunatitative Structure-activity relationship)
ADMET (absorption, distribution, metabolism, excretion, toxicity)
3. Lead Identification
- Triterpene have diverse structure and pharmacological activities
- Several naturally occurring triterpenes have been reported to show anti-HIV activity
- Bevirimat, the first in a new class of compound termed HIV maturation inhibitor(Mis)
- betulinic acid and platanic acid can inhibit HIV-1ⅢB replication (EC50/bet 1.4 μM /
EC50/pla 6.5 μM)
- betulinic acid contains many plant species
( e.g Tryphyllum peltatum, Ancistrocladus heyneanus, Ziziphi fructus, Tetracera
boloviana )
- betulin can modify to betulinic acid (betulin in birch bark)
4.Lead Optimisation and SAR Study
4.1 Modification of the BA Triterpene Skeletion
- Betulinic
acid
have
a
readily
chemical
modification site
C–3 alcohol
C–19 isopropenyl
- C–3 alcohol
C–28 carboxyl group
- C–19 isopropenyl
- C–28 carboxyl group
This functional group
This
functional
group
This functional group can
undergoes typical reaction
be derivatised providing
with allylic group
ester and amide
can be eliminated or
oxidised
- C–28 carboxyl group
EC50 23μM / TI value
1.9
- C-2 Hydroxylation
EC50
- C–19 isopropenyl
reaction
with
Pd-C
activity)
(Catalytic hydrogenation)
EC50 0.9μM / TI value 14
- C–3 alcohol Oxd
EC50 0.22μM
CC50 0.9μM (cytotoxic)
42.3μM(weak
4.2 Modification on C-3 Position of BA
Com 8, 9 ) Extremely potent anti-HIV
- C-3 hydroxyl group readily acylated
with variety of anhydrides and acid
chlorides
1
activity
Com 15, 16) similar potencties compare
com 8,9
Com 10, 17 ) reduction in antiviral
2
activity
Com 13, 20~22 ) lack or no antiviral
activity
Com 7, 11, 12, 14, 18 ) partial antiviral
activity
- C-3 modification’s result indicates that the two C-3’ methyl group
in the bevirimat side chain contribute anti-HIV activity and terminal
carboxyl acid substitution has antiviral activity potent
Similar activity
Moderate
activity
- C-3 position of BA and betulin,
geminal dimethyl substitution of
the side chain C-3’ position
coupled
with
a
terminal
carboxylic acid are important to
the enhanced antiviral activity for
both
of
templates
these
triterpene
C-3 stereo
C-3 stereo convert
eliminate
Two compound anti-viral activity dramatically reduced, indicating the importance of the 3-C stereo
R
S
- C-3
oxygen
exchange
with
nitrogen
Only com 42, 45 weak antiviral
activity
- com 46 have similar activity compare buletin(com 4)
but have cytotoxic (EC50 0.22μM / CC50 0.9μM)
- Similary com 47 has antiviral activity and cytotoxic
(EC50 0.22μM / CC50 0.9μM)
- com 48~50 has similar antiviral activity but decrease
cytotoxic (EC50 0.57~4.57μM / CC50 ＞15μM)
4.3 Introduction of C-28 Side Chain into BA
- These type functions by blocking the viral entry into the host cells
- Increasing chain length influence the anti-HIV potency
- compound with amide side chains between aminooctanoic acid and aminododecanoic acid
tend to increase antiviral potency
- com 51 inhibits the infectivity of several HIV-1
strains (EC50 0.05~2μM)
- com 52 equipotent antiviral activity
- com 53 have equipotent against
HIV-1 virus when compare with
com 51, com 52
- com 51 show potent antiviral activity
in vitro but its clinical development
was
stopped
due
to
‘pharmacodynamic properties’
poor
4.4 Bifunctional BA Analouges – Potential for Maturation
Inhibitor Development
- Two functionalities are on the opposite position of the BA skeleton
- a design combining both modifications led to the development of bi-functional BA
analogues
- EC50 0.0026μM higher potent than C-3 and C-28 parent compound
- This category preserves both the anti HIV-1 entry and maturation inhibit ability
5. Mechanism of Action Studies of Bevirimat
- Bevirimat affect virus replication at a time
point after the completion of viral DNA
integration and Tat expression
- inhibited the processing of the viral Gag
polyprotein at a specific step
- Bevirimat does not affect viral RT, reverse
protease, virus particle budding
- Bevirimat
blocks processing of CA-
SP1(p25) to CA (p24) which necessary for
final capsid condensation and formation of
infectious, bevirimat
cause abnormal
morphology to virus
- consequently virus become non-infectious
- Bevirimat has no effect on processing at
other site of Gag
Gag region relate virion
structural proteins protase
- Bevirimat-resistant isolates were selected by serial passage of HIV-1
- resistant virus found several point mutations proximal to the cleavage site of CA-SP1
CA H226Y, L231M, L231F, SP1 A1V and A3V
- no mutation observed in other region of Gag or in the PR coding region
- Bevirimat does not affect SIV / HIV-2
6. Preclinical Studies of Bevirimat
- EC50 10.3nM against subtype B virus
(similar activity compare withAZT,nevirapine)
-Bevirimat retains nanomolar inhibitory activity against drug
resistant HIV strains(NRTIs, NNRTIs, PIs resistant)
- no activity against HIV-2, SIV and other similar envelop
virus type
Mouse type : SCID-hu Thy/Liv
>2log10 in HIV-1 RNA
Does : Twice daily / Oral
≥ 90% p24 conc.
Virus : HIV-1 infected
Gag-p24+ thymocytes at 100mg/kg per day
Dose-dependent manner
Observe in the mice at plasma conc.
7. Clinical Trials and Current Status of Bevirimat
- Phase Ⅰ(In 2004 completed)
PanocosPharm dose single and multiple phase clinical trials of bevirimat in
healthy volunteers / Oral solution
It well tolreated half-life of ~ 2.5-3 days / supporting daily dosing regimen
- Phase Ⅱa (In August 2005, completed)
random double-blind, bevirimat monotherapy for ten days resulted in statistically
significant reduction in viral load compare with placebo (individual decrease up to
1.7log10, 100 and 200mg dose)
No evidence develop drug resistant virus
7. Clinical Trials and Current Status of Bevirimat
- Phase Ⅱb (In 2008 completed)
patients failing HIV therapy due to drug resistance
Good activity in 369, 370, 371 on Gag amino acid sequence mutant, less activity
in polymorphism(variants)
20μg/mL bevirimat is required for a robust response
the mean viral load reduction was -1.18log10copies/mL after 14days in the patients
who free of key baseline Gag polymorphism and bevirimat conc. Minimum target
of 20μg/mL
91% of patients with these two response predictors han at least a 0.5log10 viral
load reduction by week 2 with a maximum treatment response of 2.03log10
7. Clinical Trials and Current Status of Bevirimat
- Phase Ⅱb (In 2008 completed)
bevirimat well tolerated, with a safety profile comparable to placebo through the
14days of treatment
Bevirimat tablet formulation dosed twice daily achieved target plasma levels
After 14 days of bevirimat treatment given twice daily at doses of 200mg or
300mg(using the 50 mg tablet)
32% patient (treatment naïve and experienced) had plasma concentrations
well above the previously identified minimum target of 20μg/mL
PhaseⅢ are being planned
8. Conclusions
- HAART has led to a significant improvement in the health and life span
HIV-1-infected patients
- But,
major
problem
is
the
increasing
prevalence
of
virus
strains
that are resistant to approved drug
- Plants are a major source of biologically active compounds and can provide
good leads that are structurally unique and/or have new mechanism of action
Thank You for Your Attention