Enzyme Replacement Therapy:

Lesson from Gaucher Diseases

Yoga Devaera, Damayanti Rusli SjarifDiv Pediatric Nutrition and Metabolic Diseases

Dept of Child Health – FKUI/RSCM Jakarta - Indonesia

After the lecture you should make a flowchart of how the

enzyme replacement therapy generated Collect it tomorrow to your chief of the class

Assignment

Introduction

Enzyme replacement therapy

Summary

Outlines

They are looking for the answers to three basic

questions: Is there a disease? What causes it? Can we prevent, treat, or cure it?

How do scientists investigate diseases?

Is there a disease ?

What’s wrong with this child?

Splenomegaly In 1882, the French

medical student Phillipe Charles Ernest Gaucher described a 32-year old woman whose spleen was very enlarged.

Gaucher cells

A postmortem exam revealed that spleen infiltrated by cells, which typically are large, pale, polyhedral shaped cells possessing a single, relatively small, eccentrically located nucleus

Phillipe Charles Ernest Gaucher

Gaucher disease

Did people with Gaucher disease exist before

1882 ?

Yes, they did. But because a set of symptoms wasn't identified with the condition, "Gaucher disease" as a disease diagnosis did not exist.

Question 1

What causes it?

What Causes It? In 1934, the French

chemist A. Aghion discovered the chemical cause of the enlarged spleens and liver: a buildup of a lipid (fatty substance) called "glucocerebroside."

did people with Gaucher disease make too much of

the lipid for their bodies to handle? Or did their bodies not break it down and dispose of

it?

Why there was too much lipid in Gaucher cell ?

The answer to this question came during the

early 1960s, when Dr. Roscoe Brady's group showed that people with Gaucher disease made the lipid normally

but did not make enough of the enzyme "glucocerebrosidase" to break it down and clear it out of the body.

Development of a Gaucher cell

Gaucher’s disease is resulting from either

severely decreased functioning or a complete lack of lysosomal acid β-glucosidase or

glucocerebrosidase

Causes?

A single mutation in the gene coding for GCase can result

in partial (60-70%) or complete lack of enzyme activity (Lieberman et al. 2007).

In affected cells, glucosylceramide accumulates and is difficult to remove (glucosylceramide forms deposits within macrophages called Lewy bodies that these cells can't break down)

Buildup of glucosylceramide within macrophages can lead to simultaneous enlargement of the spleen and liver, abnormal bone turnover, and diseases of the central nervous system in more severe cases (Lieberman et al. 2007).

Next findings

In 1967, Brady's group developed a convenient

diagnostic test for Gaucher disease which works by measuring the activity of the enzyme glucocerebrosidase in white blood cells.

The amount of enzyme directly relates to how severe a case of Gaucher disease

The enzyme activity is also one way that may help to distinguish the three types of Gaucher disease described in this chart.

Enzyme activity

The Three Types of Gaucher Disease  Type 1 Type 2 Type 3Whom it Strikes young adults

/ adultsinfants children/

young adults

Distinguishing symptom

no nervous system problems

early nervous system problems

later onset of nervous system problems

Effects of disease varies from mild to severe

dies in infancy

becomes severe

Glucocerebrosidase Activity

some activity but much less than normal

very little activity

little activity

"Why do some people make too little enzyme?"

The answer to this question came in 1987, when the first gene mutation that causes Gaucher disease was discovered by Dr. Shoji Tsuji and coworkers.

chromosome 1

How Gaucher disease is passed on ?

Autosomal recessive

In the early 1970s, Dr. Brady's group devised

an enzymatic test based on the enzyme's activity to tell people if they were carriers or not, and

a procedure for prenatal diagnosis. These tests give people information about their

genetic status so that they can prepare for the future.

Enzymatic based diagnosis

Can We Prevent, Treat, or Cure It?

The third question that medical researchers try to

answer is the most important, and often depends on the answer to the question what the cause of it ?

To be truly successful, a treatment would have to address the cause of the disease, not just the symptoms.

For Gaucher disease, physicians initially attempted to

address the symptoms that accompany the disease. They removed enlarged spleens, and performed liver

transplants, blood transfusions, and orthopedic procedures.

Only bone marrow transplantation for people with Type I Gaucher disease was sometimes successful.

mutation in gene coding enzyme

mutated enzyme

loss ofenzyme activity

accumulation of substrate

cell dysfunction / biochemical and pathological change

clinical symptoms

The Pathophysiology of IEMs

The Principle of Treatment

gene mutation

mutated lysosome enzyme

loss ofenzyme activity

accumulation of substrate

cell dysfunction / biochemical and pathological change

clinical symptoms

modification ofmutated protein

ChemicalChaperone

inhibition ofsubstrate synthesis

SubstrateDeprivation

supplementationof enzyme protein

ERT

BMT

Gene Therapy

ERT

In 1966, Dr. Roscoe Brady suggested a therapy for

Gaucher disease based on replacing the enzyme. Using human placentas, Dr. Peter Pentchev of Dr.

Brady's team isolated a tiny sample of purified glucocerebrosidase.

Enzyme Replacement Therapy

In 1973, Brady put that enzyme into two splenectomised

patients with Gaucher disease. The first patient was a 15 year old boy with Type 3 Gauchers

disease. a liver biopsy was obtained, the enzyme at ½ u/kg/bw (unit

per kilo of bodyweight) was given and two days later performed another liver biopsy → a 26% reduction of the accumulation of glucocerebroside in the liver biopsy.

The second patient also showed a 26% decrease. The third patient received 2½ u/kg/bw but the reduction was

only 8%

Development ERT

A large-scale purification method was completed in 1977.

The enzyme had to be treated with an alcohol to make it stick to the purifying columns.

But this preparation of the enzyme produced inconsistent results during clinical trials. No reduction of hepatic (liver) glucocerebroside occurred in 4 out

7 patients who received this preparation The alcohol had removed a lipid (fat) that activates the

enzyme and targets it to the affected cells, called macrophages.

Development ERT

The problem was

the glucocerebrosidase was not going into the macrophages, the cells in the liver, spleen and bone marrow

that accumulate glucocerebroside: 95% of the infused enzyme was going to other cells, primarily hepatocytes in the liver, and being wasted.

Dr. Brady's challenge was now to get the purified enzyme into the targeted cells.

Development ERT

John Barranger, Clifford Steer and Scott Furbish removed

oligosaccharides from the enzyme so that the mannose (a sugar at the end of the sugar side chains) would attach to the macrophage.

Modified Enzyme

In the first clinical trial with macrophage-targeted

glucocerebrosidase, eight people with Gaucher disease received a fixed dose of the modified enzyme. Only the smallest one - a child - experienced beneficial

effects. He was given 13 u/kg/bw every week.His hemoglobin and platelet counts increased; the size of his spleen and liver decreased; and the damage to his bones lessened.

Then deliberately stopped the enzyme infusions and his haemoglobin and platelets gradually decreased to pre-infusion values.

Development ERT

When re-instated his enzyme infusions at 30 u/kg/bw, his blood

counts rose to normal range, there was a reduction in the size of his spleen and liver and the damage to his bones improved.

The other seven people were adults and had not received enough of the enzyme to improve their condition.

It was at this point that Henri Termeer (now President

and Chief Executive Officer of Genzyme Corporation) learned about the work.

Henri raised 10 million dollars to produce enough enzyme for a clinical efficacy trial.

Brady's team then carried out a dose response study and elected to give patients 60 u/kg/bw every two weeks. In this clinical efficacy trial, all 12 patients improved.

All of these people had strikingly good clinical responses within a few months. For example, their height and weight increased; their anemia improved; their liver and spleen sizes decreased; and their bone damage lessened.

Dose Response Study

Hemoglobin Chart

Before and after X-

Rays

Macrophage-targeted glucocerebrosidase was

approved as a specific treatment for Gaucher disease by the Federal Drug Administration on April 5, 1991.

Enzyme replacement therapy worked. Ceredase worked and the recombinant enzyme Cerezyme is just as good.’

Enzyme replacement therapy is an effective treatment for most people with Type 1 Gaucher disease.

FDA approval

FDA approval

ERT for Gaucher Diseases

PretreatmentFemale; Age 8 Years, 8 Months

Post-treatmentFemale; Age 10 Years, 10 Months

Gaucher’s patient Response to Enzyme Therapy

Courtesy of NW Barton. Developmental and Metabolic Neurology Branch of the NINDS.

Therapeutic Goals and Monitoring for Type 1

Gaucher Disease

Recombinant Enzyme Disorder Comment

Imiglucerase Nonneuronopathic (type 1) Gaucher disease

reported to reduce hepatosplenomegaly, improve anemia and thrombocytopenia, and reduce episodes of pain crises in these patients.Because the recombinant enzyme does not cross the blood-brain barrier, it is not effective in type 2 Gaucher disease patients with severe CNS abnormalities

Alpha-galactosidase (2003) Fabry disease

Improvement in pain and gastrointestinal symptoms has been reported, but long-term studies are required for evaluating its efficacy with respect to life-threatening complication

Laronidase (2003) MPS Ireported improvements in hepatosplenomegaly and respiratory disease and showing a decrease in urinary glycosaminoglycan excretion. Hematopoietic Stem Cell Transplantation (HCT) is currently the mainstay of therapy for MPS I

Arylsulfatase B (2005) MPS VI (Maroteaux-Lamy syndrome)

associated with improvements in hepatosplenomegaly, joint movement, cardiopulmonary function, and pain as well as reduced excretion of urinary glycosaminoglycans

Alglucosidase alpha Infantile Pompe diseaseA portion of infants who are diagnosed and treated with ERT before 6 months of age had improved survival and quality of life compared with the observed natural history of the disease, yet, for unknown reasons, a subset of the treated cohort did not show effects from ERT

Idursulfase MPS II (Hunter syndrome)

Clinical trials showed improvement in cardiopulmonary disease and hepatosplenomegaly and decreased excretion of urinary glycosaminoglycans

ERT in Pompe diseases

Pompe: patient response to enzyme therapy

MPS 1: Improved Joint Range of Motion

Pretreatment Posttreatment 26weeks

Mean Changes in the Restriction of Range of Motion in

Patients with Mucopolysaccharidosis I during -l-Iduronidase Therapy

ERT has little effect on the brain, skeletal tissue, and

valvular heart disease in LSDs. ERT treats only the symptoms and not the underlying

disease Lifelong frequent infusions (weekly to monthly depending

on the protocol) The estimated cost of ERT is between

$90,000 to $565,000 (US), depending on the disease (therapy) and patient size.

Intravenous infusions of GCase are administered weekly and it can cost a patient from $100,000 to $750,000 per year (Sawkar et. al, 2002).

Infusion reactions including fatal anaphylaxis have been reported

Limitations of enzyme replacement therapy

Other therapy options are

highly desirable !!!!

How about Indonesia ?

K, female, 8 years old Suspected Fabry since 3 years old Diagnosed Fabry at 8 years old ERT cost

Rp 180.000.000,-/month Lifelong Donation ?

Fabry Diseases : Waiting for ERT

Fabry disease progression

Clinical staging of Fabry disease in the kidney. (Reproduced

with permission from Branton MH, et al. Medicine. 2002;81:122-38.)

F, 3 years old boy diagnosed as MPS IVA (Morquio

Syndrome) No ERT available yet Trial of ERT beginning 2012 in Taiwan, refused because of

nationality

MPS IVA : Waiting for ERT (trial)

Thank you

Gaucher disease - massive

splenomegaly

splenomegaly

The enlarged cells (now called "Gaucher cells") and spleen became signs of the disease.

Gaucher's description of the them enabled other physicians to diagnose people with Gaucher disease, and introduce the term into medical literature

Lysosomal glucosylceramide accumulation in Gaucher stabilizes α-synuclein oligomers ► α-synuclein inhibits

lysosomal trafficking of glucocerebrosidase in synucleinopathies