PSTC pre-meeting points and Hy's Law Definition - AASLD

1) Guidance document:
• Hy’s law:
(Some) questions on DILI assessment and guidance
(Predictive Safety Testing Consortium & IMI, pre-meeting)
o How can we minimize false positives; how should we deal with e.g. Gilbert’s patients
o Can the ALP criterion be replaced by use of ratio R
o eDISH plot: use of peak vs concurrent values. Use both
• Can we replace ALT/AST by ALT only
• Approach to liver safety in patients with baseline liver abnormalities, e.g. oncology patients
with and without liver mets, hepatitis C patients
• Suitable risk management – contingent on database size, signal, patient population
2) Liver safety assessment and reporting
• Use of graphics in addition to tables and listings
• Using methods for outlier detection to understand and differentiate liver safety signals
• Using multivariate reference ranges for LFTs: adding value
3) Inclusion of exploratory liver safety biomarkers in development programs: how to encourage
4) Collaborative efforts for liver safety assessment: how to share data, expertise, resources
5) Align liver safety assessment with FDA and EMA: organize joint workshop

Hy’s Law definition
Suggested updates to the July 09 FDA Guidance:
Drug-Induced Liver Injury: Premarketing Clinical
Evaluation
2

Revised definition of Hy’s Law suggested
• Hy’s Law event is “ominous” – so precise classification needed:
– hepatocellular injury 1 w/o alk phos restrictions of greatest concern 2
– alk phos >2xULN observed in one third of Hy’s law cases 2
– 96% of liver death/transplant seen with hepatocellular injury 2
• Hy’s Law event not met if:
• direct bilirubin normal (or 2xULN
• peak bilirubin elevation precedes ALT elevation
1
Danan G J Clin Epidemiol, 1993. 46(11): p. 1323-30 [hepatocell. Injury defined as ALT>2xULN & ALT (ULN)/alk phos (ULN) >5]
2
http://www.aasld.org/conferences/Documents/PresentationLibrary/2010Hepatoxicity_SessionIV_Kaplowitz.pdf
3

All Hy’s events should assess hepatocellular injury
w/o alk phos restrictions & bilirubin fractionation
• Hy’s Law event is “ominous” – so immediate evaluation requires:
– bilirubin fractionation
– bilirubin concomitant with or following ALT elevation on eDISH
– hepatocellular injury 1 w/o alk phos restrictions of highest concern 2
– alk phos >2xULN observed in one third of Hy’s law cases 2
– 96% of liver death/transplant seen with hepatocellular injury 2
• Gilbert’s syndrome and/or drug-induced inhibition of bilirubin
conjugation/transport can be assessed by:
– bilirubin fractionation yielding predominantly indirect bilirubin
– UGT1A1 genotyping
– pretreatment labs revealing asymptomatic hyperbilirubinemia
1
Danan G J Clin Epidemiol, 1993. 46(11): p. 1323-30 [hepatocell. Injury defined as ALT>2xULN & ALT (ULN)/alk phos (ULN) >5]
2
http://www.aasld.org/conferences/Documents/PresentationLibrary/2010Hepatoxicity_SessionIV_Kaplowitz.pdf
4

“Hy’s Law”
• 10-50% patients with drug-induced
hepatocellular jaundice will have fatal
liver failure 1
• FDA: “ALT >3xULN and bili >2xULN” is
an indicator of significant concern,
termed “Hy’s Law” 2
• 9-12% mortality when drug-induced
liver injury accompanied by
ALT>3xULN and jaundice in DILI
registries 3,4 Hyman Zimmerman 5
5
1
Zimmerman HJ. Hepatotoxicity (Philadelphia: Lippincott, Williams and Wilkins), 1999.
2
FDA http://www.fda.gov/downloads/Drugs/GuidanceComplianceRegulatoryInformation/Guidances/UCM174090.pdf
3
Bjornsson E. Hepatol 2005; 42: 481-489.
4
Andrade RJ. Gastroenterol 2005; 129: 512-521.
5
http://jama.ama-assn.org/content/283/6/812.full.pdf+html

Hy’s Law cases uncommon in FDA Submissions 1
• FDA retrospective review of 26 NDAs (2004)*, of
which 13 drugs “hepatotoxic” & 13 “nonhepatotoxic”:
– Hy’s Law case present in only 3 of 26 NDAs:
• Tacrine
• Metformin, topirimate
1
Lana Pauls; FDA website: http://www.fda.gov/downloads/Drugs/ScienceResearch/ResearchAreas/ucm080526.ppt
6

Bilirubin concom. or following ALT in DILIN 1
• NIH DILI 1 - median duration from DILI recognition:
Peak ALT = 1 (0 –7) days
Peak alkaline phosphatase = 4 (0 –16) days
Peak total bilirubin = 7 (0 –17) days
• DILI with jaundice (total bilirubin 2.5 mg/dL):
median time from peak to 50% decrease: 13 days (4–30)
median time from peak to bili 2.5mg/dl: 26.5 days (3-54)
• Significantly higher mortality: hepatocellular DILI with bili>2.5 mg/dL vs.

Bilirubin rises concomitantly or after ALT in Hy’s Law events
90% of Hy’s events have bilirubin elev. within 32days
Age/ Peak ALT Peak Peak alk phos Days from ALT>2xULN
Gender
bilirubin
to bilirubin>2xULN
39M 66xULN 7xULN Alk phos =2xULN 0
F 24xULN 5.5xULN Alk phos

Direct bilirubin increases with liver injury
• Bilirubin is typically measured with two assays to
assess total & “direct reacting” bilirubin 1
• direct bilirubin 0.1mg/dl in normals, 1 10-15% of total 2
• direct bilirubin increased with liver injury & sepsis
• Bilirubin autoanalyzer measurement assoc. with:
– 20% analytic variation
– 30% biologic variation 1
9
1
Dufour DR et al. Clinical Chemistry. 46(12):2050-68, 2000.
2
Bircher J et al. Oxford Textbook of Clinical Hepatology (Oxford University Press, Oxford UK)
Roy-ChowdhuryN et al. Chapter 2.3.5 Bilirubin metabolism p. 168, 1999.

Notable bilirubin biologic variability
• Gilbert's Syndrome affects 3-10% overall 1 , innocuous inherited disorder of
bilirubin conjugation resulting in mild, variable bilirubin elevation:
• affecting 2-5% of Caucasians, 3% of Asians, and 36% of Africans 2
• Bilirubin is conjugated through uridine-diphosphate glucuronosyltransferase
(UGT-1A1) to water-soluble bilirubin diglucuronide, secreted in the bile
• In Gilbert’s syndrome, a polymorphism in the promoter region of the UGT-
1A1 gene 2 reduces bilirubin glucuronidation approx. 30%, 1 elevating:
• total bilirubin
• unconjugated (or indirect) bilirubin
10
1
Danoff TM. The Pharmacogenomics Journal 2004;4:49–53.
2
Burchell B. J Gastro Hepatol 1999:14:960-966.

Tranilast inhibits bilirubin conjugation, so
bilirubin>2xULN with Gilbert’s syndrome 1
11 1
Danoff TM. The Pharmacogenomics Journal 2004;4:49–53.

Bilirubin and bile salt transport are affected by:
• Decreased by drug-induced or toxic injury 1 , sepsis & inflammation 1
• Bilirubin is:
– taken up in liver cell by OATP1B1 2
– Conjugated by UGT1A1
– Conjugated/direct bilirubin is exported by MDR1 and MRP2 into bile 2
• Diverse drugs may affect bilirubin conjugation or transport 1
• So, Gilbert's Syndrome (TA7/TA7 genotype of UGT1A1) subjects are more
likely to develop drug–induced hyperbilirubinemia & Hy’s Law events
12
1
Geier A. Biochimica et Biophysica Acta 2007: 1773: 283–308
2
Kamisako M. J Gastroenterol 2000; 35:659–664

Bilirubin and Bile Salt Liver Disposition
blood
MRP3
Unconjugated
Bilirubin
hepatocyte
bile
blood
Bilirubin
Bile salts
OATP1B3
OATP1B1
NTCP
UGT1A1
Conjugated
Bilirubin
glucuronide
MDR1 & 3
MDR1
MRP2
Bile salts
BCRP
BSEP
MRP3
MRP2
13
blood
bile
Inhibition may cause
accumulation

14
Representative Hy’s Law cases

Concomitant peak ALT & bilirubin
Lab test
ALKALINE PHOSPHATASE
BILIRUBIN TOTAL
SGOT (ASAT)
SGPT (ALAT)

Homozygous wild type UGT1A1 (so no Gilbert’s syndrome)
Oct 10-22
Dashed reference
lines at 1, 2, and
3xULN
16

Homozygous wild type UGT1A1 (so no Gilbert’s syndrome) with
150 day period between ALT>3xULN and bilirubin>2xULN

Are these Hy’s Law cases

Adjudicated as possible DILI - is this a Hy’s Law case
Hyperbilirubinemia preceded & followed ALT elevations
Lab test
ALKALINE PHOSPHATASE
BILIRUBIN TOTAL
SGOT (ASAT)
SGPT (ALAT)
19

Gilbert’s syndrome and peak bilirubin preceding peak ALT
adjudicated as probable drug-induced liver injury
Lab test
ALKALINE PHOSPHATASE
BILIRUBIN TOTAL
SGOT (ASAT)
SGPT (ALAT)
Dashed reference
lines at 1, 2, and
3xULN