©2016 Vertex Pharmaceuticals Incorporated 1

Aldehyde Oxidase Metabolite as

a Perpetrator of Drug-Drug

Interactions

DDI Conference 2017

Craig Zetterberg, Francois Maltais, Leena Laitinen,

Shengkai Liao, Hong Tsao, Ananthsrinivas

Chakilam and Niresh Hariparsad

Introduction

• Time-dependent inhibition (TDI) typically occurs when a

drug forms a reactive metabolite which irreversibly binds

and inactivates metabolic enzymes

• Traditionally screened using human liver microsome

(HLM) assay

• Precipitants of TDI are not always the product of phase I

oxidative metabolism!

©2016 Vertex Pharmaceuticals Incorporated 2

CYP2C8 TDI - System-dependent outcome

©2016 Vertex Pharmaceuticals Incorporated 3

Microsomal data from Ogilve, et al. Hepatocyte experiment by Vertex DMPK

IC50

shifted

10-fold

HLM HHep

Published accounts of non-CYP mediated TDI

• Gemfibrozil and Clopidogrel: both drugs have glucuronide

metabolites that inactivate CYP2C8

• Bupropion: reduction by CBR/AKR to more potent CYP2D6

inhibitors

• Ezetimibe: UGT-mediated protection against CYP3A4 inactivation

(no clinical DDI)

• VX-509: AO metabolite (M3) victimizes CYP3A4

©2016 Vertex Pharmaceuticals Incorporated 4

Hepatocyte TDI Assay Method

• Plated hepatocytes in separate 96-well per time point

– No centrifugation

– Individual well viability to account for cell loss due to wash, toxicity

• Stagger addition of 2X inhibitor to cells containing equal volume

of media

• Inhibitors simultaneously removed by rapid inversion, washed 3X

• “Wash out” 60 min

• Luminescent CYP3A4 substrate

• Fluorescent viability assay

©2013 Vertex Pharmaceuticals Incorporated 5

Assay/Donor Reproducibility

©2016 Vertex Pharmaceuticals Incorporated 6

In vitro inhibition parameters correspond with literature

©2016 Vertex Pharmaceuticals Incorporated 7

In vitro inhibition parameters predict DDI

©2016 Vertex Pharmaceuticals Incorporated 8

Fa assumed = 1.0

Purines and other

heterocyclic amines

are typical

substrates of

Aldehyde Oxidase

Hutzler et al. 2013

How do we Measure AO Activity?

In Vitro

Not present in microsomal fractions

Found in cytosolic fraction, S9 fraction, hepatocytes

– Reagent vendors have characterized AO activity in commercially

available preparations

Commercially available inhibitors

– Raloxifene works in cytosol and S9

– Hydralazine is works in hepatocytes

In Vivo

Rat, mouse, dog not good preclinical species

Guinea pig and monkey have AO

©2016 Vertex Pharmaceuticals Incorporated 11

VX-509 M3

M3 generated in cytosolic incubations

©2016 Vertex Pharmaceuticals Incorporated 12

VX-509

M3

M3

VX-509

M3 generated in rAO incubations

©2016 Vertex Pharmaceuticals Incorporated 13

©2016 Vertex Pharmaceuticals Incorporated 14

VX-509 M3

Liver Microsomes

Hepatocytes

Comparison of hepatocyte lot AO activity

©2016 Vertex Pharmaceuticals Incorporated 15

0 1 0 2 0 3 0 4 0

H H 8 0 0 4

B P B

H u 8 1 2 3

H H 1 0 0 7

Y O W

V m a x P h th a la z in e

(p m o l/m in /m illio n c e lls )

Km = 0.4-0.8 µM

CYP3A4 TDI - System-dependent Outcome

©2016 Vertex Pharmaceuticals Incorporated 16

Inhibition of M3 formation

©2016 Vertex Pharmaceuticals Incorporated 17

Predicting VX-509 DDI from in vitro inhibition parameters

©2016 Vertex Pharmaceuticals Incorporated 18

Summary

• TDI for lead compounds can be investigated using hepatocytes

to capture interplay between enzyme families

• Can be especially valuable if compound is cleared by non-CYP

metabolism

©2016 Vertex Pharmaceuticals Incorporated 19