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A single nucleotide polymorphism in CYP2B6 leads to >3-fold increases in efavirenz concentrations in intensive pharmacokinetic curves and hair samples
M. Gandhi, R.M. Greenblatt, P. Bacchetti, C. Jin, Y. Huang, M. Cohen, J. Dehovitz, K. Anastos, S.J. Gange, C. Liu, S. Hanson, B. Aouizerat
for the Women’s Interagency HIV Study (WIHS)
Pharmacokinetics and Pharmacogenomics of ART: Coming of Age
Oral poster discussion, AIDS 2012, Washington DC, July 24
TUPDB0104
Background
EFV mainstay of current cART, high rates of AEsPharmacogenomics (PG) “personalize” selection, dosing; optimize outcomesStudies investigating PG & EFV exposure limited bySingle plasma levels of EFV as exposure measureSmall # single nucleotide polymorphisms (SNPs) examinedFailure to model non-genetic contributors
Women’s Interagency HIV Study (WIHS): Multicenter prospective cohort study HIV-infected and at-risk
women
Methods: EFV AUC- “Short-term exposure”
24 hour intensive PK studies performed in 111 WIHS women on EFV under conditions of actual useAreas under the curve (AUCs) calculated
0
5
10
15
Efa
vire
nz c
once
ntr
atio
n(m
cg/m
L)
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24
Time of blood draw (hours)
Median PK curve
Efav
irenz
con
cent
ratio
n (m
g/m
l)
Time of blood draw (hours)
Hair EFV levels: “Long-term exposure”
Average exposure over time
Not snapshot (AUC of AUC)
Easy and cheap to collect
Stored at room temp
Shipped without biohazard
Not subject to white coat effects
Integrates behavior (adherence) and biology (PK)
Methods (cont.)
Multivariate linear regression between predictors and short/long-term exposureGenetic predictors: 182 SNPs/ 45 haplotypes in 9 genes (ABCB1, ABCC2, CYP2B6, CYP2C19, CYP2D6, CYP3A5, CYP3A4, SCL22A6, UGT1A1)
Literature-based: SNPs -EFV absorption, distribution, metabolism, elimination (ADME)Tag SNPs: Neighboring regions in high LD across coding/noncoding regions of ADME genes
Non-genetic: Diet, age, race, HepB/C status, smoking, substance use, hepatic, renal function, etc.
ResultsFactors associated with short-term EFV exposure
(AUC/dose, n=111)
Factor Effect on AUC (±95%CI) p-value Distribution of
factorOranges or orange juice in preceding 5 days
1.26 (1.05 -1.50) 0.012 76 (68.5%)
Per doubling of ALT level 1.23 (1.11-1.36) 0.0001 Median ALT (range)
23 (8-117) IU/L
CYP2B6 983 T>C (rs28399499) 0 doses of minor allele (TT) 1 or 2 doses of minor allele (TC/CC)
1.001.96 (1.54-2.5)
2.2 x 10-10 95 (85.6%) -0 dose16 (14.4%) -1/2 dose
CYP2B6 516 G>T (rs3745274) 0 or 1 doses of minor allele (GG, GT) 2 doses of minor allele (TT)
1.003.5 (2.7-4.5)
1.4 x 10-18 97 (87.4%) – 0/1 dose14 (12.6%)-2 doses
ABCB1 haplotype (2 SNPs: rs7779562 & rs4148745) 0 doses of the haplotype 1 or 2 doses of haplotype
1.00
1.60 (1.24-2.1) 0.0004
14 (12.6%)-0 dose97 (87.4%)- 1/2 doses
Results
Factors associated with long-term exposure (hair levels/dose, n=87) –models include adherence
Factor Effect on hair (±95%CI) p-value Distribution of
factorALT, Orange juice, ABCB1 haplotype, and self-reported adherence (below) not significantly associated with hair levels
CYP2B6 983 T>C ( rs28399499) 0 doses of minor allele (TT) 1 or 2 doses of minor allele (TC/CC)
1.001.70 (1.09-2.7)
0.021 77 (88.5%) -0 dose10 (11.5%) -1/2 doses
CYP2B6 516 G>T (rs3745274) 0 or 1 dose of minor allele (GG, GT) 2 doses of minor allele (TT)
1.003.2 (2.2-4.7)
1.0 x 10-1074 (85.1%) -0/1 dose13 (14.9%) – 2 doses
Self-reported adherence ≤74% 75-94% ≥95%
1.000.94 (0.45-2.0)1.10 (0.56-2.2)
0.880.77
4 (4.6%)14 (16.1%)69 (79.3%)
Conclusions
Individuals homozygous CYP2B6 516 rare (TT) allele >3-fold increases in short-term (AUCs) and long-term (hair) EFV exposure in this diverse cohort of HIV-infected women
AUCs more robust than single plasma levels (and self-reported adherence) as short-term measures, cumbersomeHair levels better in averaging exposure over time
Effect of CYP2B6 516 TT on long-term exposure signifies durable effectsGenetic testing coupled with hair measurement may enable EFV dosing optimization in clinical setting, especially when non-genetic risk factors for high exposure are present
Acknowledgements
Participants and staff of the WIHSFunding NIAID/NIH RO1 AI065233 (Greenblatt); UO1 AI034989
(Greenblatt); NIAID ARRA 3U01AI034989-17S1 (Greenblatt, Aouizerat); K23 AI067065 (Gandhi)
THANK YOU!