Overcoming the Barriers of Clinical Translation: The Abacavir Example Elizabeth J. Phillips, MD, FRCPC, FRACP Professor & Director, Centre for Clinical Pharmacology & Infectious Diseases, Murdoch University Royal Perth Hospital, Sir Charles Gairdner Hospital Perth, Western Australia ASCEPT December 1, 2009

Translation is an Active Process Pharmacogenetic/genomic Discovery -Intepretable and cost- effective test -broad uptake in clinical practice -positive impact on patient effiacy and/or safety “Lost in Translation” <1% >99% -improved understanding of pathophysiology of disease, mechanism of drug efficacy, toxicity -identification of new therapeutic targets

T1  T4: The Translational Paradigm Step 1 - A discovery with a potential application Step 2 - Generation of high-level clinical evidence - Basic science supports biological plausibility - Basic science supports biological plausibility Step 3 - Delivery of research to the clinic - Quality assurance, valid, efficient and - Quality assurance, valid, efficient and inexpensive lab testing and lab report easy to interpret Step 4 - Evaluation of test in real clinical practice

Abacavir causes abacavir hypersensitivity (ABC HSR) in 5-8% 1998 Two independent groups describe strong association between ABC HSR and HLA-B*5701 in predominantly Caucasian populations Apparent low sensitivity of HLA-B*5701 in non- white populations questions generalisability Clarity added to the “False positive clinical diagnosis “ of ABC HSR, observational studies Patch testing is a highly specific for “true” ABC HSR Randomised clinic trial using patch testing confirms utility of HLA-B*5701 and case-control study generalisability across ethnicity Widespread uptake into clinic in developed world, incorporation into treatment guidelines, test reimbursed ABACAVIR CLINICAL ROADMAP –

HLA-B*5701 & Abacavir Lancet March 30, 2002 Lancet March 2, 2002

HLA-B*5701 and Abacavir Hypersensitivity: A Comparison of Two Studies *Caucasians only Observed sensitivity and specificity PV assumes prevalence of ~9% PosNeg Mallal et al, 2002 HLA-B*5701 Hetherington et al, 2002* HLA-B Pos PVNeg PV 74%98% HSR No HSR Sens 78% Spec 97% PosNeg Pos PVNeg PV 82%96% Sens 55% Spec 99% Mallal, et al. Lancet 2002;359: Hetherington, et al. Lancet 2002;359:

Early Problems with “Phenotype” MallalCNA30027CNA30032 WhiteBlack 78% 57% 48% 8% Early studies have observed variable sensitivity of HLA-B*5701 -Definition of abacavir hypersensitivity reaction (ABC HSR) nonspecificity of clinical phenotyping  false positive clinical diagnosis -Differences in white and nonwhite races Sensitivity of HLA-B*5701 Mallal et al. Lancet 2002 Hughes et al. Pharmacogenomics 2004

Phenotypic Uncertainty of Abacavir HSR Blinded Study AbacavirGroups Zidovudine or indinavir CNA /268 (7%) 6/265 (2%) CNA /324 (8%) 10/325 (3%) Total Cases 46/592 (7.8%) 16/590 (2.7%) Cases in CNA30024 as reported by Investigators in the ABC HSR CRF Module Hernandez, et al. ADR/Lipodystrophy 2003.

Patch Testing Following Abacavir (ABC) Exposure Presentation by epidermal Langerhans cells Sensitization Local Reaction ABC  Reactive Metabolite (Antigen) Alcohol dehydrogenase (Abacavir) Conjugation with host protein in skin CYP450 CD8+ Prior ABC ingestion Day 0>6 weeks later Phillips et al AIDS 2002;16:223, Phillips et al AIDS 2005;19:979. Phillips E, Mallal S. Mol Diag Ther 2009;13:19

Abacavir Skin Patch Testing 3 previously assigned cases had diagnosis revised (1) Concurrent NNRTI therapy (2) Negative patch test Patch testing Previously assigned cases Carriers of 57.1 AH markers 9/9 Non-57.1 carriers (NNRTI+) 0/3 Non-57.1 carriers (NNRTI-) 1 patient unavailable ABC HSR ABC non-HSR Previously assigned tolerant Carriers of 57.1 AH markers 0/5 Martin, et al. PNAS 2004;23;101:

HLA-B*5701 and Abacavir Hypersensitivity Reclassified first 200 patients (*not available) Martin, et al. PNAS 2004;23;101: PosNeg HLA-B* * 4180 Pos PVNeg PV 78.9%99.4% Sens 93.8% Spec 97.8% HSR No HSR

First Randomised Study to Examine Utility of Pharmacogenetic Test to Decrease toxicity N Eng J Med 2008;358:568-79

High Negative Predictive Value of HLA- B*5701 Generalised Across Race SPT-pos (n=42/42) 100% CS-HSR (n=57/130) 44% Control (n=194/202) 96% SPT-pos (n=5/5) 100% CS-HSR (n=10/69) 14% Control (n=204/206) 99% White Black Sensitivity/Specificity of HLA-B*5701 and 95% CI OR: White IC-HSR 1945 [ ]; CS-HSR 19[8-48] Black IC-HSR 900 [ ]; CS-HSR 17[4-164]

Incorporation of Screening into Clinical Trials *All 4/725 (0.8%) patients in ARIES study clinical diagnosed with HSR were patch test negative AIDS 2008;22(13):1673-5

DHHS Guidelines: Jan IAS Guidelines: JAMA 2008;300(5): Preferred NNRTIEFV ABC/3TC (for HLA-B*5701 negative patients) or TDF/FTC PI FPV/r BID LPV/r BID ATV/r ABC/3TC (for HLA-B*5701 negative patients) or TDF/FTC Incorporation of HLA-B*5701 Testing into Treatment Guidelines

Laboratory Translation* Cost Turn-around- time Feasibility High resolution HLA B typing High (>$500 USD) Long (2 weeks or more) Not feasible unless specialty laboratory PCR-based techniques Moderate (<$100 USD) Moderate (<2 week) Feasible for labs with molecular technologies B17-monoclonal Flow Cytometry Low (<$50 USD) Low (mandated by need for fresh cells) For labs doing CD4+/8 *Ongoing quality assurance program mediated by ASEATTA Phillips and Mallal, Mol Diag Ther 2009;13(1): 1-9

Cytosol (1) Abacavir (5) ER HLA-B*5701 Class I MHC Tapasin TAP B2mB2m (1) Abacavir H2NH2N HOHO O N N N (9) Pro-inflammatory cytokines (8)Abacavir specific CD8+ T- cell (6) Golgi N Unknown cytosolic protein? (3) Proteosome (4) Haptenated peptide (10) Hypersensitivity symptoms Cytosol Hsp-70? ADH Abacavir (2) Metabolism ADH? Reactive metabolite (7) Surface of APC HLA-B*5701+ TcR abacavir hapten OH R R H R H R H R H R H R H R H R H N R H (4) Haptenated peptide OHR R= H2NH2N N NH N N APC Phillips E and Mallal S. Mol Diag Ther 2009;13(1): 1-9

Number Needed to Test... DRUGHLA Allele HLA Carriage Rate Prevalence of diagnosis of HSR or SJS/TEN in high risk populations Negative Predictive Value Approx. Minimum Number needed to test to prevent “1” AbacavirB* % Caucasian <1% African/Asian 2.5% African American 5-8% (includes 3% true HSR and 2-7% false positive diagnosis) 100% for patch test confirmed 14 AllopurinolB* % Han Chinese 1-6% Caucasian 1/250100% in Han Chinese 250 CarbamazepineB* % Han Chinese <0.1% Caucasian 1-6/ % in Han Chinese 200

Challenges to Translation – Beyond Abacavir  More prospective studies needed but difficulties in generating high level evidence for generic drugs (???funding)  Generalisation difficulties for other drugs (negative predictive value of HLA-B*5801 and HLA-B*1502 will be <<<100% in Caucasians)  Specificity of phenotype (lack of “patch test” equivalents)  Single gene/allele associations will be unlikely for most drugs

AcknowledgmentsAcknowledgments Simon Mallal James McCluskey David Nolan Dianne Cheesman Ian James Tess Lethborg Mina John Tony Purcell Annalise Martin Emma Hammond Annette Patterson Mandvi Bharafway Campbell Witt Richard Harrigan Frank Christiansen Andri Rauch Rom Kreuger Amalio Telenti Susan Herrmann Hansjakob Furrer Coral-Ann Almeida Julio Montaner GSK and PREDICT-1 and SHAPE investigators and study teams National Health and Medical Research Council of Australia Simon Mallal James McCluskey David Nolan Dianne Cheesman Ian James Tess Lethborg Mina John Tony Purcell Annalise Martin Emma Hammond Annette Patterson Mandvi Bharafway Campbell Witt Richard Harrigan Frank Christiansen Andri Rauch Rom Kreuger Amalio Telenti Susan Herrmann Hansjakob Furrer Coral-Ann Almeida Julio Montaner GSK and PREDICT-1 and SHAPE investigators and study teams National Health and Medical Research Council of Australia Participants and clinical staff involved in the Western Australian HIV Cohort Study Canadian Foundation for AIDS Research Canadian Dermatology Foundation

“In the middle of difficulty lies opportunity” “We can’t solve problems by using the same kind of thinking we used when we created them” Albert Einstein