Transcript Issues of - AETC-NMC

Presented by Keith W. Crawford, R.Ph., Ph.D.
Clinical Research Associate, Department of Clinical
Pharmacology,
Johns Hopkins School of Medicine, Clinical Pharmacology
Baltimore, MD.
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Identify two ways that the course of HIV infection might be different in
individuals infected by different subtypes/clades.
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Define polymorphism and understand that these genetic variations that
may affect protein function can occur at different frequencies across
racial/ethnic groups
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Provide an example of how a polymorphism can affect the response to a
drug and why a particular population may be at higher risk for such an
effect.
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Understand that herbal products used in traditional medicines may have
unpredictable effects on HIV control.
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Ethnopharmacology refers to the unique use of drugs
and effects of drugs in different ethnic populations
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From one angle, we can examine the use of medicinal
plants among different ethnic groups
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We can also study varying responses of drugs between
different ethnic groups (Pharmacogenetics). We will
focus on this area and how it applies to HIV disease.
HIV-1
HIV-1
Group:
O
HIV-2
(less pathogenic)
M
N
(Cameroon)
Clade:
A,C,F
(Africa)
B
(U.S., Europe)
E
Others
(S.E. Asia)
Levy JA. HIV and the Pathogenesis of AIDS. 2nd ed. Washington, DC: American Society for Microbiology;
1998:152-158.
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Different clades/subtypes have different efficiencies of
heterosexual transmission

Different clades/subtypes have different rates of mother-tochild transmission
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Clades/subtypes produce disease progression at different
rates (in the absence of therapy)

Whether differences exist between clades/subtypes in antiretroviral drug potency and treatment response is an area of
active clinical investigation.
X4
CD4
CCR5
CXCR4
T-cell lines
R5
X4/R5
Dual
Primary lymphocytes
Monocyte/macrophages
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Phenotypic coreceptor tropism of gp160 env sequences
cloned from 68 antiretroviral-naive, pregnant Ugandan
women
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36% of subtype D samples vs none of subtype A or A/D
samples were D/M
Phenotypic Tropism
Test Result, %
CCR5 tropic*
CXCR4 tropic†
Subtype A
(n = 33)
Subtype A/D
(n = 10)
Subtype D
(n = 25)
100
100
100
0
0
36
*Response range ~ 104-106 RLU.
†Response range ~ 200-105 RLU. Threshold for CXCR4 use = 200 RLU.
Huang W, et al. J Virol. 2007;81:7885-7893.
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Subtype C HIV is among the most widely distributed
variants in east and southern Africa
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In some studies, X4 tropism is not found in treatmentnaïve patients with subtype C virus
(Cecilia et al., 2000,Virology 271:253-258, Bjorndal et al. AIDS Res. Hum.
Retrovir. 1999, 15:647-653, Tscherning,et al. Virology, 1998 241:181-188)
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X4-tropism (dual/mixed) is seen with increasing
frequency upon treatment failure, similar to the case in
subtype B virus (Johnston et al.,Virol. 2003 Jul;77(13):7682-8.)

Chaplin et al., AIDS Res Hum
Retroviruses. 2011 Jan;27(1):71-80.

Munerato P et al. AIDS Res Hum
Retroviruses. 2010 Mar;26(3):265-73.
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T.G. is a 32 yo woman originally from Sierra Leone. She
is first diagnosed with HIV in September 2001 after
being in the US for 5 years

Her CD4+ cell count is 328 cells/ml and her HIV RNA is
102,000 copies/ml
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She is started on a regimen of Sustiva and Combivir

In January 2002 her CD4+ cell count is 579 and her HIV
RNA is <50 copies

In April 2002, her CD4+ cell count has dropped to 402
cells, but she remains undetectable

In July of 2002, her CD4+ cell count is now 245, yet her
viral load is still undetectable.
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Why is her CD4+ cell count steadily dropping? She has
had no opportunistic infections. The decline is likely not
due to adherence since she consistently is
undetectable.

She is tested for HIV-2 and found to be positive. She was very
likely infected in Sierra Leone.
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HIV-2 is not sensitive to Sustiva. Combivir is the active
component of the regimen and dual-nucleoside therapy was not
adequate for sustained suppression of HIV-2
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The patient is likely having a rebound of HIV-2 (resistant to
AZT/3TC), causing CD4+cell decline while the HIV-1 is remains
totally suppressed by the regimen.
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The regimen was changed to a PI-based regimen including
abacavir, which lead to CD4+ cell recovery
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Substance abuse, particularly stimulant use, is
very common among gay men and is
associated with increased numbers of partners
and unprotected anal intercourse
(e.g. Mimiago et al., Drug Alcohol Depend. 2010;110(1-2):30-7)
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Leaves from the plant Catha
edulis are dried and chewed for
the stimulant properties of khat
This plant is grown in North and
East Africa and the middle East
for it’s stimulant effects
Abuse of khat is a serious
medical problem in Africa and
parts of Asia with striking
parallels to the crackcocaine/methamphetamine
epidemic in the US
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Alkaloids of Catha edulis, cathinone and cathine
have sympathomimetic effects and stimulant
activity
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Pharmacologic actions similar to those of
amphetamine
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Khat alkaloids increase dopamine concentrations
in the critical brain regions for addiction, just as
amphetamine but less potent than amphetamine
in some brain areas
Amphetamine
Cathinone

Khat use is associated with high-risk sexual behavior in
region with high HIV prevalence Alemu et al., J Health Popul Nutr. 2007
Sep;25(3):344-50; Taffa et al Int J STD AIDS. 2002 Oct;13(10):714-9.

Khat and its synthetic derivative can be purchased over
the internet Wood DM et al.J Med Toxicol. 2010 Sep;6(3):327-30.
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Clinicians treating patients from Ethiopia, other parts of
East Africa and the Middle East should include
discussions about khat use when evaluating Mental
Health and substance abuse in HIV treatment or
prevention programs

All proteins involved in pharmacokinetics (drug absorption,
distribution, metabolism and excretion) are under genetic
control

Alleles are genetic variants in a particular trait and at a specific
genetic locus
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Genetic variation within a specific locus are called
polymorphisms

These genetic differences in nucleotide sequence can affect the
functioning of the protein or even the protein’s expression

The frequency of a polymorphism in a population often differs
across racial and/or ethnic groups
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Polymorphisms in metabolic enzymes can result in
increased or decreased enzyme activity
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These changes can translate into decreased or increase
plasma drug concentrations, respectively
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Drug concentration determines drug efficacy as well as
drug toxicity
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Efavirenz Plasma
Concentration (µg/mL)
10,000
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1000
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100
8
10
12
14
16
Time After Dose Intake (hr)
Marzolini C, et al. AIDS. 2001;15:71-75.
18
20
Haas D W et al. J Infect Dis. 2005;192:1931-1942
Efavirenz AUC0-24hr(g x hr/mL)
All Subjects
European
Americans
African
Americans
250
200
150
100
50
0
GG GT TT
Haas DW, et al. AIDS. 2004;18:2391-2400.
GG GT TT
GG GT TT
CYP2B6 G516T genotype
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Many drugs are substrates for transport proteins that
regulate their distribution into tissues.
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Transporters are involved in intestinal absorption, drug
uptake by hepatocytes (metabolism) and bile
(elimination), and entry and efflux from renal tubules
 Examples:
▪ P-glycoprotein (gut, kidney)
▪ MRP’s (kidney, gut)
▪ SCLO (liver)
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Disparities in treatment outcomes for hepatitis C by race and
ethnicity are well established.
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hENT is a major transport protein involved in uptake of ribavirin
into cells (also AraC in leukemia and lymphoma therapy).
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SLC29A1 is the gene that produces hENT and genetic
polymorphisms affect the expression of hENT
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-706 G>C polymorphism affects the expression of the gene and
is present in 21% of Caucasians but only 5% African-Americans.
Two polymorphisms were found only in African-Americans, 1345C>G and -1050G>A with allele frequencies of 8% and 19%
(Myers et al.,Pharmacogenet Genomics. 2006 May;16(5):315-20).
Main Predictors of Rapid Virological Response to Peginterferon-Ribavirin Therapy in Patients
Coinfected with Human Immunodeficiency Virus and Hepatitis C Virus (HCV).
Morello J et al. J Infect Dis. 2010;202:1185-1191
© 2010 by the Infectious Diseases Society of America
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Weight-based dosing has been recommended for some
antiretroviral drugs (e.g. stavudine, didanosine) which could
possibly minimize toxicities while maintaining efficacy.
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ART’s used at approved doses, based on phase II/III studies in
Caucasians, may have different pharmacokinetic profiles
when used at these doses in other populations
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These differences can be due to differences in body weight
and composition as well as pharmacogenetics
Rozenberg al., AIDS. 2009 Nov 27;23(18):2439-50.
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CCR5 is a receptor for the chemokines MIP-1α, MIP-1β expressed
on the surface of macrophages and memory T-lymphocytes
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CCR5 is required as a co-receptor for HIV to infect these cells
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A 32-base pair deletion mutation polymorphism in the CCR5 gene
results in a impaired receptor expression and impaired ability of
HIV to infect these cells. Delta-32 deletion homozygotes are Longterm non-progressors in HIV disease

This observation suggested that CCR5 could be a target for HIV
therapy which lead to development of the chemokine receptor
antagonists (e.g. Maraviroc).
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Homozygous
 ~ 1% of white population[1]
 Lack CCR5 molecules on CD4+ cell surface[2,3]
 Relatively normal immune function
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Heterozygous
 10% to 15% of white population[1]
 Fewer CCR5 molecules on CD4+ cell surface[4]
 Normal immune function[2]
1. McNicholl JM, et al. Emerg Infect Dis. 1997;3:261-271. 2. Liu R, et al. Cell. 1996;86:367-367. 3. Samson
M, et al. Nature. 1996;382:722-725. 4. Wu L, et al. J Exp Med. 1997;185:1681-1691.

Abacavir produces a potentially fatal hypersensitivity
reaction in about 5% of users

A polymorphism in the HLA-B genetic locus (HLA-B*5701)
was found associated with abacavir hypersensitiviy in whites
and Latinos, but in African-Americans, initial studies found it
alone lacked sufficient predictive value to identify patients at
risk (Hughes, et al., Pharmacogenomics. 2004 Mar;5(2):20311).

The rate of hypersensitivity is higher in whites, from 5-8%,
compared to about 3% in African-Americans
Sensitivity of HLA-B*5701 Test
Patient Group, %
White Patients
Black Patients
44
14
100
100
96
99
CS-HSR
Skin test positivity
Control
Saag et al.,Clin Infect Dis. 2008 Apr 1;46(7):1111-8
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Digitalis from Foxglove – CHF, atrial
fibrillation
Cinnchona alkaloids from Cinnchona
bark – quinidine–anti-arrhythmic,
quinine – anti-malarial
Coumadin from Red clover –
anticoagulant
Salicylates from Willow bark – aspirin
- anti-inflammatory, analgesic, antipyretic
Cocaine from Coca leaves – local
anesthetic
Opioid alkaloids from Poppy –
morphine – analgesic for moderate
to severe pain
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Artemisinins –anti-malarials
Vinca alkaloids from Periwinkle,
vincristine, vinblastine – anti-cancer
Ergot alkaloids from fungus,
Claviceps pupura – migraine
treatment and prophyllaxis, obstetric
complications
Rauwolfia alkaloids - reserpine –
HTN, schizophrenia
Guanidine from Goat’s Rue –
Diabetes
Penicillins –from molds
Tetracyclins- from molds
Taxanes – from Yew, paclitaxel,
taxotere for treating various tumors

What dose is most effective and how often should it be given? No
dose studies are done for most herbal products so where do the
recommended doses come from?
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How much of the specified compound is actually in the product?
In some studies, analysis found none of the “medicinal” compound
in the product. Herbal products have no regulation.
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Is the product safe? Herbal products have no safety requirements
and seldom identify any precautions. People have died from using
some of these products (e.g. Ephedrine)
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Does the product actually work? Efficacy studies are not required
to market supplement product.

Plants produce varying quantities of alkaloids based
on there growing conditions

There are seasonal variations in the quantity of
“medicinal” product produced by the plant
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Variation in extraction procedures result in varying
efficiencies in yield of the product. There is often
little standardization of this crucial process
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Calanolide A is one of the most potent
inhibitors of HIV from natural sources
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Derived from the Southeast Asian plant
Calophyllum lanigerum
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Inhibits HIV reverse transcriptase at
concentrations comparable to antiretrovirals
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St. Johns Wort reduces the bioavailability of
indinavir
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Garlic supplementation decreased the
bioavailabilty of Saquinavir
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Milk Thistle shown not to have an effect on
indinavir levels
Piscitelli et al., Lancet. 2000 Feb
12;355(9203):547-8.
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Among many ethnic groups, traditional medical practices may
include the use of herbal therapies. Which statement is correct
about herbal treatments and HIV disease?
A. Because herbal products are natural, the body can handle the
compound differently than it does synthetic drugs, and hence, herbs
are not toxic.
B. These products may have interactions with antiretroviral drugs that
can affect their efficacy
C. These products are regulated by the Food and Drug administration
as “foods” and are proven to be safe
D. Both A and C are correct
E. All of the above are correct

Goulda Downer, Ph.D., RD, LN, CNS - Principle
Investigator/Project Director (AETC-NMC)

Tina Edmunds-OGBUOKIRI Pharm.D

I Jean Davis, PhD, PA, AAHIVS

Michael R. Noss, DO

Josepha Campinha-Bacote, PhD, MAR, PMHCNS-BC,
CTN-A, FAAN
1840 7th Street NW, 2nd Floor
Washington, DC 20001
202-865-8146 (Office)
202-667-1382 (Fax)
Goulda Downer, Ph.D., RD, LN, CNS
Principle Investigator/Project Director (AETC-NMC)
www.AETCNMC.org
HRSA Grant Number: U2THA19645
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