CFTR Modulation – 25 Years of NACFC Progress

Marcus A. Mall, M.D.Division of Pediatric Pulmonology and CF Center

Department of Pediatrics

University of Heidelberg, Germany

NACFC Motivation

Courtesy of Jeff Wine

Early NACFC Milestones: Unraveling the Cause of Cystic Fibrosis

Closed

OpenTime

CurrentCl-

Courtesy of David Sheppard

Gibson RL et al., Am J Respir Crit Care Med 2003

Most CF is Caused by a Processing Defect of F508 CFTR

Courtesy of Martina Gentzsch

CFTR

F508

Lukacs GL et al., New Engl J Med 2003

F508

CFTR Dysfunction Causes Airway Surface Liquid Depletion

Normal CF

Ion transport defectAirway surface dehydration

Mucociliary dysfunction

Mucus obstruction

InfectionInflammation

Lung damage

Courtesy of Ric Boucher

Ratjen F, New Engl J Med 2006

Human Bronchial Epithelial Cultures

(HBE)

Different Mechanisms of CFTR Dysfunction and Proof of Concept for Mutation-Specific Therapies

Rowe SM et al., New Engl J Med 2005

Courtesy of M Gentzsch

Low temperature correction

Potentiation of channel gating

Courtesy of D Sheppard

Translational readthrough

Placebo Gentamicin Wilschanski M et al., NEJM 2003

High-Throughput Screening Speeding Up CF Drug Discovery

>10,000 Primary assays/day

High-throughput screening

High-throughput screening

CFTR Modulator Drug

SAR based Medicinal Chemistry

Prioritize hitsPrioritize hits

Screening Assay

Courtesy of Vertex Pharmaceuticals

2011 Clinical Studies with CFTR Modulators

Rowe SM et al., New Engl J Med 2005

CFTR potentiator VX-770:Phase III study in CF patients with the G551D CFTR mutation

CFTR corrector VX-809:Phase IIa study in CF patients with the F508 CFTR mutation

Ataluren (PTC124):Phase III study in CF patients with CFTR nonsense mutations

– ongoing –

Results from First Phase III Clinical Study with CFTR

Modulator

Efficacy and Safety of VX-770

in Subjects with CF

and the G551D Mutation

See talk by BW Ramsey: W23 (Saturday, 2:30 PM) – Poster #211

Potentiator VX-770 Restores G551D CFTR Function and Improves Airway Surface Hydration in Vitro

Unt

reat

ed

VX

-770

Unt

reat

ed

0

20

40

60

80

100

120

G551D/F508del-HBEWild-type-HBE

CFT

R A

ctiv

ity(%

wt-C

FTR

)

VX-770Control

Unpublished data provided by Vertex

0.2 sec

Inte

nsity

Control VX-770

Cilia beat frequency (representative tracings)

Airway surface liquidASL

Van Goor F et al., PNAS 2009See poster by B Woodworth: #114

VX-770 Phase III Study Design

• Randomized, double-blind, placebo-controlled • Recruitment: 161 subjects• Key inclusion criteria

– G551D mutation on at least one CFTR allele– Aged ≥ 12 years– FEV1 40% to 90% predicted

Run-inScreening

Randomization(1:1)

Or 2-yr Follow-up

VX-770 150 mg q12hVX-770 150 mg q12h

Open-label rollover study

Placebo Placebo

Day -35 -14 0 48Week 24

VX-770 VX-770 150 mg q12h150 mg q12h

VX-770 VX-770 150 mg q12h150 mg q12h

Treatment period Extension period

Primary analysis

Elborn JS, 34th ECFC 2011http://clinicaltrials.gov (NCT00909532)

VX-770 Phase III Study Endpoints

Primary Endpoint• Absolute change from baseline in % predicted FEV1 through week 24

Secondary Efficacy Endpoints• Absolute change from baseline in sweat Cl–

• Absolute change from baseline in CFQ‑R respiratory domain• Absolute change in weight • Time to first pulmonary exacerbation• Absolute change from baseline in % predicted FEV1 through week 48

Safety Assessment• Adverse events (clinical laboratory values, ECGs)

Elborn JS, 34th ECFC 2011http://clinicaltrials.gov (NCT00909532)

Day 15 Week 8 Week 16 Week 24 Week 32 Week 40 Week 48-60

-55

-50

-45

-40

-35

-30

-25

-20

-15

-10

-5

0

5

PlaceboVX-770

Ch

ang

e in

sw

eat

chlo

rid

e co

nce

ntr

atio

nm

mo

l/L

(m

ea

n,

95

% C

I)

Change from Baseline in Sweat Chloride

Treatment effect through Week 24– 47.9 mmol/L

P < 0.0001

Treatment effect through Week 48– 48.1 mmol/L

P < 0.0001

Elborn JS, 34th ECFC 2011Vertex press release June 10, 2011

Day 15 Week 8 Week 16 Week 24 Week 32 Week 40 Week 48-5

0

5

10

15PlaceboVX-770

Ab

solu

te c

han

ge

in %

pre

dic

ted

FE

V 1(m

ea

n,

95

% C

I)Absolute Change in FEV1 % Predicted

Treatment effect through Week 24

+ 10.6 % P < 0.0001

Treatment effect through Week 48

+ 10.5 % P < 0.0001

Elborn JS, 34th ECFC 2011Vertex press release June 10, 2011

Time to First Pulmonary Exacerbation

Week 24 Hazard Ratio

0.40 P = 0.0016

Week 48 Hazard Ratio

0.46 P = 0.0012

0.78

0.51

0.67

0.41

0.0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1.0

0 28 56 84 112 140 168 196 224 252 280 308 336 364

Hazard Ratio: 0.45 ( 0.28, 0.73) P=0.0012

PLACEBO VX-770Event-Free Rate At Week 48 0.41 0.67

PLACEBO VX-770Event-Free Rate At Week 48

Placebo

VX-770

Pro

por

tion

of e

ven

t-fr

ee s

ubje

cts

Study day

Modified Fuchs’ criteria

Elborn JS, 34th ECFC 2011Vertex press release June 10, 2011

Change from Baseline in CFQ-R Respiratory Domain

Day 15 Week 8 Week 16 Week 24 Week 32 Week 40 Week 48

-10

-8

-6

-4

-2

0

2

4

6

8

10

12

PlaceboVX-770C

han

ge

in C

FQ

-R r

esp

irat

ory

do

mai

np

oin

ts (

me

an,

95%

CI)

* MCID, minimal clinically important difference (Quittner et al 2009)

MCID = 4*

Treatment effect through Week 24

+ 8.1P < 0.0001

Treatment effect through Week 48

+ 8.6P < 0.0001

Elborn JS, 34th ECFC 2011;Vertex press release June 10, 2011

Change from Baseline in Weight

Day 15 Week 8 Week 16 Week 24 Week 32 Week 40 Week 48

-1

0

1

2

3

4

5PlaceboVX-770

Ch

ang

e in

we

igh

tkg

(m

ea

n,

95%

CI)

Treatment effect at Week 24+ 2.8 kg

P < 0.0001

Treatment effect at Week 48+ 2.7 kg

P = 0.0001

Elborn JS, 34th ECFC 2011Vertex press release June 10, 2011See talk by M Drumm: S1 (Thursday 2:00 PM)

Safety Summary Through Week 48

Adverse event, n (%)Placebo(N = 78)

VX-770(N = 83)

Subjects with any serious adverse event 33 (42.3) 20 (24.1)

Pulmonary exacerbation (physician determined) 26 (33.3) 11 (13.3)

Hemoptysis 4 (5.1) 1 (1.2)

Hypoglycemia 0 2 (2.4)

Serious adverse events occurring in > 1 subject in either group

Adverse event, n (%)Placebo(N = 78)

VX-770(N = 83)

Any adverse event 78 (100) 82 (99)

Adverse events leading to study discontinuation 4 (5) 1 (1)

Elborn JS, 34th ECFC 2011Vertex press release June 10, 2011

Summary of VX-770 Phase III Study in CF Patients with the G551D Mutation

• Rapid onset and sustained improvement in lung function (primary endpoint: absolute change in % predicted FEV1)

• Parallel improvement in CFTR function and lung function

• Sustained improvements in other outcomes including risk of exacerbation, respiratory symptoms and weight gain

• No important safety concerns

For more information on other VX-770 studies, see posters by R Ahrens, E McKone & P Flume: #s 203, 204 & 206, respectively

Questions Arising from the First CFTR Modulator Studies

How Much CFTR Function Is Required to Ameliorate or Prevent CF?

Sweat test nasal PD

Hirtz S et al., Gastroenterology 2004Knowles MR et al., Human Gene Therapy 1995Wilschanski M et al., Am J Respir Crit Care Med 2006

~20%

~35%

Isc rectal biopsies

~30%

Effect of VX-770 on CFTR Function in CF Patients with the G551D Mutation

Accurso FJ et al, New Engl J Med 2010

Sweat test Nasal PD

See talk by SM Rowe: S14 (Friday 10:30 AM)See poster by JP Clancy: #202

Which Outcome Measures Will Capture Therapeutic Benefits of CFTR Modulation?

Restoration of mutant CFTR function

Mucociliary clearance

InflammationMicrobiology

Lung functionLung structureClinical outcomes

The G551D Observational (GOAL) StudyDay 1Day 1

Pre-Dose First dose of VX-770

1 month after day 1

3 months after day 1

6 months after day 1

Core Study Measures Additional Sub-Study Measures

• Clinical outcome• Sweat chloride• Quality of life

• CFQ-R• SNOT-20

• Biomarker collection• Serum• Plasma• DNA• Urine• Sputum

• Clinical outcome• Sweat chloride• Quality of life

• CFQ-R• SNOT-20

• Biomarker collection• Serum• Plasma• DNA• Urine• Sputum

VX-770 not prescribed

yes

no

MCC/Rheology – visits 2, 5

• Radionuclear mucociliary clearance• Micro-rheology• Bulk rheology

MCC/Rheology – visits 2, 5

• Radionuclear mucociliary clearance• Micro-rheology• Bulk rheology

Sputum Inflammation & Microbiome – visits 2,5

• Induced sputum• Inflammatory mediators

Sputum Inflammation & Microbiome – visits 2,5

• Induced sputum• Inflammatory mediators

Sweat Rate – visits 1 to 5

• Sweat evaporimetry• Exploratory sweat outcomes

Sweat Rate – visits 1 to 5

• Sweat evaporimetry• Exploratory sweat outcomes

Intestinal pH – visits 2, 3

• Intestinal pH by radiofrequency transmitter

Intestinal pH – visits 2, 3

• Intestinal pH by radiofrequency transmitter

Visit 2Visit 2 Visit 3Visit 3 Visit 4Visit 4 Visit 5Visit 5

Visit 1bVisit 1b

Visit 1Visit 1

Decision made to start

VX-770?(before end of

study enrollment)

Decision made to start

VX-770?(before end of

study enrollment)

Courtesy of Steven Rowe

See talks by C De Boeck & N Yang: S14 & S19 (Friday 10:30 AM & Saturday 10:30 AM, respectively)See posters by F Ratjen, T Altes & T Gonska: #s 201, 205 & 213, respectively

Relationship Between Timing of CFTR Modulator Treatment and Clinical Benefit?

Progression of CF Lung Disease

Birth Childhood Adult

Reversible Irreversible

Normalairway

Mucus &Air trapping

Airway wall thickening Bronchiectasis

Adapted from Ramsey BW, PATS 2007

Window of opportunity

See talk by SM Stick: S5 (Thursday, 2:00 PM) See posters by T Nguyen, L Mott & M Rosenfeld: #s 88, 332 & 335

CF newborn screening

CF Lung Disease Starts in Infancy

Sly PD et al, Am J Respir Crit Care Med 2009

Bronchial dilatation (19%)Normal

Bronchial thickening (45%) Air trapping (67%)

Early “Causal Therapy” Prevents Decline of Lung Function in COPD

Fletcher C & Peto R, Br Med J 1977

Progress in Correcting F508 CFTR

CFTR

F508Courtesy of Martina Gentzsch

VX-809 Corrects F508 CFTR in Primary Human Bronchial Epithelial Cultures

VX-809Cl-

Cl-

Cl-

F508

Cl- Cl- Cl-Cl-

Cl-

Van Goor F et al., PNAS 2011

F508 HBE

F50

8 A

ctiv

ity

Results of Phase IIa Study of VX-809 in CF Patients Homozygous for F508 CFTR

Clancy JP et al. Thorax 2011

No significant differences in:• Adverse events• Nasal PD• Lung function• Patient-reported outcomes

VX-809 versus placebo for 28 days (n=89)

Combination of VX-809 + VX-770 for F508 ongoing

See talk by SM Rowe: S15 (Saturday, 10:30 AM); See talk by M Boyle: W23 (Saturday, 2:30 PM) – poster #212

CFF 2010 Strategic Planning Meeting on Development of Next Generation

F508 CFTR Correctors

Recommendations:• Development of new lead compounds that rescue F508 CFTR

activity to critical threshold (goal: 50% of normal CFTR activity)

• Conduct two independent HTS discovery assays (functional and mechanistic)

• Use human airway epithelia as early as possible in the discovery process

• Increase the number of compounds tested in primary screening assays

See poster by F Liang: #190

Recent Results from CFTR Folding Consortia: F508 Interferes with at Least Two Steps in CFTR Folding

NBD1 Folding

F508

Domain Assembly

F508F508

NBD1

NBD2

Serohijos AWR et al., PNAS 2008Mendoza JL et al., J Bioenerg Biomembr 2007

See talks by R Ford, P Thibodeau: S4 (Thursday, 2:00 PM)See poster by A Aleksandrov: #17

wt CFTR

MSD2

R

NBD1

folded

ΔF508 Cell Surface Expression Is Synergistically Rescued by NBD1 and NBD1-CL4 Interface Stabilization

-

WT

folded

ΔF508-CFTR+R1S +R1070W

R

MSD2

ΔF508NBD1-R1S

1070W

R1S0

20

40

60

80

100

CFTR

sur

face

den

sity

(%)

non-native

ΔF508-CFTR

R

MSD2

ΔF508NBD1

-

ΔF508

ΔF508-CFTR +R1070W

R

MSD2

ΔF508NBD1

1070W

1070W

-

ΔF508-CFTR +R1S

R

MSD2

ΔF508NBD1-R1S

R1S

- WM Rabeh & GL Lukacs

ΔF508 Function Is Synergistically Rescued by NBD1 and NBD1-CL4 Interface Stabilization

+ CFTR Inh-172

Wild-typeF508F508 + suppressor mutation F508 + R1070WF508 + suppressor mutation + R1070W

NBD1 and assembly defects corrected

See talk by JL Mendoza: W2 (Thursday 10:00) – Poster #4and talk by PJ Thomas: W12 (Friday 2:00 PM)

Correctors That Target Both Steps May Rescue Surface Expression and

Function of F508 CFTR

NBD1 Folding

Domain Assembly

Corrector A + Corrector B

F508 F508

0

5

10

Sh

ort

-Cir

cu

it C

urr

en

t,V

eh

icle

Su

btr

ac

ted

(mA

/cm

2 )Correction Activity in F508del hBE Cells

Forskolin

Forskolin + IBMX + Genistein

See talk by M Pregel: S15 (Saturday, 10:30 AM) Courtesy of Pfizer’s CF Program

Combinations of Correctors Can Produce Synergistic Rescue of F508 CFTR Function

Ongoing Efforts to Identify the Next Generation F508 CFTR Correctors

and more to follow

Effects of CFTR Modulators on Rare CFTR Mutations

• More than 1,800 CFTR mutations• Most are rare• Functional consequences often unknown

VX-770 Increases Open Probability and Cl- Transport of Rare CFTR Gating Mutants in Vitro

No

rma

l

G5

51

D

G1

78

R

G5

51

S

G9

70

R

G1

24

4E

S1

25

5P

G1

34

9D

0.0

0.2

0.4

0.6

0.8

1.0 PKA/ATP+ VX-770

CFTR Mutation

CF

TR

Cha

nne

l Po

Nor

mal

G55

1D

G17

8R

G55

1S

G97

0R

G12

44E

S1

255P

G13

49D

0

100

200

300

400

0

50

100

150

200

Forskolin

With 10 mM VX-770

CFTR Mutation

CF

TR

-Me

dia

ted

IT

(mA

/cm

2)

CF

TR

-Me

diate

d IT

(% N

orma

l)ATP

ATP G1349D

G551D,S S1255PG178R

G970R

G1244E

Mutant CFTR expressed in Fischer rat thyroid cells

Courtesy of Vertex PharmaceuticalsSee talk by F Van Goor: W12 (Friday 2:00 PM) – Poster #10

Increased Folding and Channel Activity of a Rare Folding Mutation V232D-

CFTR by Corrector Cor 4a

Caldwell RA et al., Am J Physiol Lung Cell Mol Physiol 2011

CFTR Modulators Provide Opportunity for Personalized Medicine for CF Patients

with Rare CFTR Mutations

Identify individual CFTR mutations by genotyping

Determine molecular

phenotype of rare CFTR mutations (Mutation class)

andtest effects of

CFTR modulators in vitro

Study consequence on CFTR function

and response to

CFTR modulator therapy in vivo

+ +

Identify CF patients with rare CFTR mutations who may benefit from specific CFTR modulators

CFTR2 ProjectSee talks by GR Cutting and PR Sosnay: Plenary 2 (Friday 9:00 AM)

Alternative Targets to Compensate for CFTR Dysfunction

Targeting the Epithelial Sodium Channel (ENaC) to Restore Airway Surface Liquid in CF

Tarran R et al., J. Biol. Chem. 2005

CFTRENaCENaC

ENaC

Normal CF

Normal

CF

Increased ENaC Activity Produces ASL Depletion and CF-Like Lung Disease in Mice

Wild-type ENaC-Tg

Mall M et al., Nat. Med. 2004

Inflammation

βENaC-Tg

Mucus obstruction

βENaC-Tg

Wild-type ENaC-Tg

ASLASL

See posters by A Livraghi-Butrico & T Ono: #177 & 187, respectively

-10 -9 -8 -7 -6 -5 -4

0

5

10

15

20

25

30

P643

Amiloride

Log [Drug] M

I sc

(mA

/cm

2)

Increased Potency on ENaC Decreased Rate of Absorption by HBE

Greater Durability, Increased Water Retention by Airway Epithelial Cells (8 hours)

Courtesy of A Hirsh & R Johnson, Parion Sciences

New Generation Durable ENaC Blocker P643

Enhanced Mucociliary Clearance in Large Animal Model

**

P643 Reduces Airway Mucus Obstruction and Inflammation in ENaC-Tg Mice with Chronic Lung Disease

Vehicle P643

ENaC-Tg

Wild-type

Zhe Zhou et al.

Vehicle Amiloride

ENaC-Tg

Wild-type

Amiloride study P643 study

The Calcium-Activated Chloride Channel TMEM16A as Possible Drug Target in CF

HBE

Microarrays

RNA (+/- IL-4)

Courtesy of Luis Galietta

TMEM16A

See posters by G Veit, JP Clancy, W Namkung, S Zhang & E Sondo:#s 75, 93,107, 109 & 118

Identification of TMEM16A activators by high-throughput

screening

Cystic Fibrosis Foundation Therapeutics Pipeline

CF Research and Drug Development Strategy – Leading the Way for Other Rare Diseases

Genetic defect

Basic research

Clinical research

Patients

IndustryPatient organizations

+

Abnormal protein

Disease mechanisms

Rare diseases• more than 6,000 rare diseases

• 75% affect children

• 80% have genetic basis

• often misdiagnosed

• no causal therapies

Drugs Developed for CF May Have Benefits for Patients with Common Lung Diseases

ASL Depth

Mucociliary Transport

CFTR Activity

CFTR function is reduced in cigarette smokers

HBE in vitro

Cantin A et al., Am J Respir Crit Care Med 2006Clunes LA et al., FASEB J 2011Hogg J et al., New Engl J Med 2004See poster by P Sloane: #245

Conclusion• 25 years of dedicated research have built a sound foundation

for development of drugs that target CF at root cause

• Exemplary drug development program has translated basic research findings into several small molecules that improve activity of mutant CFTR in patients

• First phase III study with CFTR modulator VX-770 showing significant clinical benefits in patients with the G551D mutation

• Robust pipeline to develop and enhance efficacy of CFTR modulators that rescue activity of other mutations including F508 to critical threshold

• Process and results of CF research may be applicable to other diseases

THANK YOU!• CF Researchers

• CF Foundation Therapeutics Development Network and Other Clinical Trial Networks (ECFS-CTN)

• CF Care Teams • People with CF and Their Families