Bruce M. Wentworth, PhD PPMD, June 24, 2010, Denver bruce.wentworth@genzyme.com

Understanding Clinical Trials:

Information is key to success

The concept of a clinical trial is simple…

Preclinical testing

Phase 1

Phase 2

Phase 3

Develop understanding of drug mechanism, potential for efficacy, dose, and evidence for toxicity

Demonstration of safety

Determine appropriate dose and gain evidence for efficacy The hypothesis generating phase

Confirmatory studies

Demonstrate how drug is to be employed

Seek Approval

Center for Study of Drug Development, Tufts University, 2006

However, the reality is often very complex ...

12.4 Years

85% 45% 70% ph1 to ph2 to ph3 to ph 2 ph3 approval

1.3 yrs

Post-Approval Studies Discovery

Preclinical Research

Preclinical Development

Pivotal Trials

Clinical Research

4.3 yrs 6.8 yrs Lengthy

Costly

w/o failures $170M w/ failures $560M w/ failures $1.2B (11.5% Discount Rate)

Risky 30.2% clinical success rate

very low preclinical

success rate

Success is rare!

regulatory review

*Recent Biotechnology industry metrics, small molecule drug metrics are similar

Phase II is the drug killer

 66% of drugs entering phase II fail prior to phase III

Paul, SM et al Nature Reviews Drug Discovery, March 2010

ZAP

Why is this process so costly?

 Can we “de-risk” it through better informed choices?

The problem is …. We don’t know enough!

Consider Pompe Disease

Cause GAA (acid maltase) gene mutation; null or ↓activity

Inheritance autosomal recessive

Prevalence ~ 1/40,000

Disease phenotype   glycogen accumulation   disruption of cellular architecture   muscle wasting and weakness, hypotonia

Clinical Presentation   “floppy baby”   considerable variability   often misdiagnosed adults

Treatment Approaches ERT, palliative care, diet & exercise

Emerging Strategies 2 gen. ERT, etc.

Infantile Pompe Is a Fatal Disease

Age (months) 0 6 12 18 24 30 36 42 48 54 60

0.0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1.0 S

urvi

val

Genzyme study (n=163), Kishnani et al J Ped 2006

Survival at 12 mos.: 26% Survival at 24 mos.: 9% Survival at 36 mos.: 7%

~ 1.54 x 106 possible variants

Alglucosidase Alfa (GAA) Molecular Complexity

P

10 10 5 11 4 7 10 significant glycan structures / site

1 2 3 4 5 6 7

rhGAA Glycans Vary With Source

some M6P little terminal mannose more sialic acid

most M6P most terminal mannose not sialylated

more M6P; GlcNac capped more terminal mannose

less sialic acid

HP-GAA

1 2 3 4 5 6 7

P P

P P

P P P

P

tgGAA

CHO- rhGAA

P

P P

6neo/6neo Pompe mouse model: the tool of choice in selecting rhGAA

  6neo/6neo mouse; Nina Raben, NIH

  Mice lack enzyme activity and accumulate glycogen similar to the human form of Pompe disease

  Onset of clinical phenotype at 6-8 months of age

Human Pompe; 30-60% Tissue Glycogen KO Mouse; 5-10% Tissue Glycogen

•  4 weekly doses; 3 mo old mice •  GAA enzyme activity

McVie-Wylie et al, Mol Gen Met, 2008

Activity of GAA in Skeletal Muscle: tgGAA > CHO-GAA ~ HPGAA

20 mg/kg 60 mg/kg 100 mg/kg

Comparison of tgGAA, CHO GAA, and HP-GAA in KO Mice

Quadriceps

0 100 200 300 400 500 600

Pre-dose Vehicle tgGAA CHO-GAA HP-GAA GA

A ac

tivity

(nm

ol/h

r/mg)

Heart

0 50

100 150 200 250 300

Pre-dose Vehicle tgGAA CHO-GAA HP-GAA

GA

A ac

tivity

(nm

ol/h

r/mg)

Clearance of Glycogen by rhGAAs

•  4 weekly doses; 3 mo old mice •  MetaMorph glycogen content

McVie-Wylie et al, Mol Gen Met, 2008

20 mg/kg 60 mg/kg 100 mg/kg

Quadriceps

0 1 2 3 4 5 6 7 8

Pre-dose Vehicle tgGAA CHO-GAA HP-GAA

% g

lyco

gen

* *

*

Heart

0 2 4 6 8

10 12 14 16

Pre-dose Vehicle tgGAA CHO-GAA HP-GAA

% g

lyco

gen *

* *

* *

*

“Mother of all experiments” conclusion

 All 3 drug candidates “worked”, but,

The drug that got to the heart the best was not the drug that cleared glycogen the best

Clearance of skeletal muscle glycogen:

CHO rhGAA > HP-GAA > tgGAA

Parameter AGLU01602 (n=18) < 6 months at ERT

Start May 2003

AGLU01702 (n=21) 6-36 months at ERT

Start March 2003

Alive 72% at 36 months age ↓risk of death by 95%

71% at study end ↓risk of death by 58%

Alive without Invasive Ventilator Support

49% at 36 months age ↓risk of inv. vent. by 91%

44% at study end ↓risk of inv. vent. by 58%

Reversal of Cardiomyopathy

(decrease in LV mass index) 94% 81%

Measurable Motor Gains 61% 62%

Alive at End of Trial (June 2006)

13 of 18 15 of 21

Clinical Trial Results in Pompe Infants: confirmation of CHO-GAA selection

Kishnani et al, Neurology, 2007, BMRA Group

Conclusion: Mechanisms matter in selecting rhGAA for treatment of Pompe disease

 We needed to understand the differences in activity of the 3 sources of rhGAA

• Before clinical development !

What about late onset Pompe patients?

40%

Infants Adults 1 year

Minimal/No activity Measurable activity

Cardiac and Muscle Muscle

Infantile-onset Late-onset

Age at Onset of Symptoms

Main Type of Tissue Involved

Amount of Residual GAA Activity (fibroblasts)

MRI reveals loss of muscle in late onset Pompe

57 yo F Onset @ 50 yo FN stage 8

39 yo F Onset @ 26 yo FN stage 4

57 yo F Onset @ 37 Fn stage 8

Early Intermediate Late

Pichiecchio et al Neuromuscular disorders, 2004 Note: This study not connected with the LOTS trial

Its difficult to rescue something that is not there

rhGAA for Late Onset Pompe Disease

 8 year old+ ambulatory patients

• A “modest” positive effect

Mean change in distance walked (m)

Mean change in % of predicted FVC

Van der Ploeg, AT et al NEJM April 2010

rhGAA demonstrated value in the treatment of late-onset patients: • Improved & maintained walking distance and breathing function

A possible explanation for the modest response of GAA in the late onset patients

 Patients present late in disease progression after damage has been done

• So, they should be treated earlier, as soon as the disease is diagnosed, to prevent further damage

 The 6MWT may be a challenging assessment in patients with significant muscle loss

• This could have implications for other myopathies

What about DMD?

Marden et al Skeletal Radiology 2005

Right Thigh

Hip region

Knee region

Muscle is lost and replaced by fatty infiltration

gluteus maximus

The 6MWT test records the state of muscle function in DMD patients as a function of time

6 M

in W

alk

Dis

tanc

e (m

)

Age (y)

 But, results interpretation may require the “complete data picture” in myopathies where muscle has been lost.

McDonald et al Muscle & Nerve 2010

Why use the 6MWT in Pompe and other diseases?

 Answer: Time

Declining ambulatory function is an important functional characteristic of Pompe and other myopathies

The 6MWT is a validated test accepted by regulatory authorities

Time spent developing new functional assays with uncertain outcome can also be spent in the clinic testing the drug in question

Take home message: learn as much as possible before clinical trial

 The attrition rate for drug candidates during clinical development is high.

 The successful approval of Myozyme depended upon understanding • the complexity of biochemical mechanisms, and, • the molecular and functional basis for efficacy

 Sole reliance on the 6MWT may present challenges in chronic myopathies where muscle is lost

Acknowledgements

 Genzyme • Alan Smith • John McPherson • Robert Mattaliano • Mike O’Callaghan • Seng Cheng • Allison McVie-Wylie • William Abernathy • Gavin Malenfant • The many members

of the Pompe team

 Colleagues at PTC

 Parent Project Muscular Dystrophy