PNH A Review and Update October 2010. PNH What is PNH? What is PNH? What causes PNH? What causes PNH? What are the clinical symptoms of PNH? What are.

PNHPNH

A Review and UpdateA Review and Update

October 2010October 2010

PNHPNH

What is PNH?What is PNH? What causes PNH?What causes PNH? What are the clinical symptoms of What are the clinical symptoms of

PNH?PNH? What are the long-term risks and What are the long-term risks and

complications of PNH?complications of PNH? How is PNH treated?How is PNH treated? What does the future hold?What does the future hold?

What is PNH?What is PNH?

Paroxysmal – Paroxysmal – sudden onsetsudden onset

Nocturnal – Nocturnal – occuring at night occuring at night (or early in (or early in morning upon morning upon awakeneing)awakeneing)

HemoglobinuriaHemoglobinuria

Despite the name, most patients do not present this way.

What is PNH?What is PNH?

A rare and unusual acquired hematologic disorder A rare and unusual acquired hematologic disorder characterized bycharacterized by• Intravascular hemolysisIntravascular hemolysis• Bone marrow failure (cytopenias)Bone marrow failure (cytopenias)• ThrombosisThrombosis

There is great clinical heterogeneity amongst There is great clinical heterogeneity amongst patients with PNH.patients with PNH.

A disease that has fascinated hematologists for a A disease that has fascinated hematologists for a long time…long time…

11stst published case report of PNH - 1866 published case report of PNH - 1866

Gull WW. Guys Hospital Reports 12:381-392, 1866.

PNH- Historical Perspective

What is PNH?What is PNH?

A rare and unusual acquired A rare and unusual acquired hematologic disorder characterized byhematologic disorder characterized by• Intravascular hemolysisIntravascular hemolysis• Bone marrow failure (cytopenias)Bone marrow failure (cytopenias)• ThrombosisThrombosis

What causes PNH?What causes PNH?

PNH is due to a change (mutation) in PNH is due to a change (mutation) in a single gene in a bone marrow a single gene in a bone marrow “stem” cell.“stem” cell.• What is a mutation?What is a mutation?• What is a stem cell?What is a stem cell?

PNH is due to a condition that allows PNH is due to a condition that allows this mutated cell to become the this mutated cell to become the dominant cell in the bone marrow.dominant cell in the bone marrow.

What is a mutation?What is a mutation?

A mutation is a “mistake” in a gene that A mutation is a “mistake” in a gene that arise when a cell divides and has to copy arise when a cell divides and has to copy the DNA. This mistake is not corrected the DNA. This mistake is not corrected and is passed on to “daughter cells” and and is passed on to “daughter cells” and all subsequent cells.all subsequent cells.

Mutations can cause:Mutations can cause:• No effectNo effect• Complete absence of the protein produced by Complete absence of the protein produced by

that genethat gene• An altered protein with decreased or different An altered protein with decreased or different

functionfunction

What is a stem cell?What is a stem cell? A stem cell has two properties A stem cell has two properties

• Can divide to produce daughter cells and more stem Can divide to produce daughter cells and more stem cells (self renewal) forever.cells (self renewal) forever.

• Can “differentiate” (mature) into many different types of Can “differentiate” (mature) into many different types of cells.cells.

Many different types of stem cellsMany different types of stem cells• EmbryonicEmbryonic• Induced pluripotent stem cells (IPS)Induced pluripotent stem cells (IPS)• Tissue specificTissue specific• HematopoieticHematopoietic

Many different sources of hematopoietic stem cellsMany different sources of hematopoietic stem cells• Bone marrowBone marrow• Peripheral bloodPeripheral blood• Umbilical cordUmbilical cord• AutologousAutologous

Hematopoietic Stem CellsHematopoietic Stem Cells

In PNH, a mutation occurs in a single gene (PIG-A) in a single hematopoitic stem cell

X

X

X

X

X X

X

X

X

X

What causes PNH?What causes PNH? The mutation in the PIG-A gene The mutation in the PIG-A gene

in a hematopoietic stem cell in a hematopoietic stem cell leads to a defect in the leads to a defect in the production of an anchor production of an anchor protein that ties other proteins protein that ties other proteins to the cell surface.to the cell surface.• Sometimes the mutation Sometimes the mutation

leads to a partial decrease leads to a partial decrease in the amount of anchor in the amount of anchor protein that is made and protein that is made and the cells have a partial the cells have a partial deficiency (Type II cells)deficiency (Type II cells)

• Some patients have several Some patients have several stem cells with different stem cells with different mutations in PIG-A genemutations in PIG-A gene

C=O

Asp

2CH

CH

C=O

O

CH

2

NH

O

PHOSPHATIDYL-

INOSITOLETHANOLAMINE

GLYCAN CORE

PROTEIN

MEMBRANE

C=O

2

O

O=P=O

O

O

CH

CH

2 CH

2 NH

CH

2

O2

O

O-P=O

O-P-O O

N

( 1-2)

( 1-6)

( 1-4)

What causes PNH?What causes PNH?

The lack of the GPI anchor protein leads to The lack of the GPI anchor protein leads to a lack of many proteins on the surface of a lack of many proteins on the surface of affected blood cells.affected blood cells.

In PNH, the major two proteins lacking on In PNH, the major two proteins lacking on the surface of the red cells are CD59 and the surface of the red cells are CD59 and CD55.CD55.

These proteins are important in protecting These proteins are important in protecting the red cells from complement.the red cells from complement.• What is complement? (three slides later)What is complement? (three slides later)

What causes PNH?What causes PNH?How do cells with a mutation take over the How do cells with a mutation take over the

bone marrow?bone marrow?

Normal people may carry cells in their bone Normal people may carry cells in their bone marrow with a PIG-A mutation, usually at a very marrow with a PIG-A mutation, usually at a very low level and probably not in a true stem cell.low level and probably not in a true stem cell.

In PNH, something allows the abnormal cells to In PNH, something allows the abnormal cells to become the dominant cells and become the become the dominant cells and become the major population in the marrow (anywhere from major population in the marrow (anywhere from 1 to over 90% - referred to as the clone size).1 to over 90% - referred to as the clone size).• This “something” may be related to aplastic This “something” may be related to aplastic

anemia, a disease of poor production of the anemia, a disease of poor production of the bone marrowbone marrow

How is PNH related to aplastic How is PNH related to aplastic anemia?anemia?

Many patients with PNH have or will Many patients with PNH have or will develop aplastic anemia, or have a history develop aplastic anemia, or have a history of having had aplastic anemia.of having had aplastic anemia.

Many PNH patients have evidence of poor Many PNH patients have evidence of poor production of cells by their bone marrow production of cells by their bone marrow (Bone marrow failure) leading to low white (Bone marrow failure) leading to low white cell counts or low platelet counts.cell counts or low platelet counts.

The cause of aplastic anemia (immune The cause of aplastic anemia (immune assault?) may also play a role in the assault?) may also play a role in the development of PNH.development of PNH.

Models of pathogenesisModels of pathogenesisNorma l Aplastic PNH MDSMarrow Anemia_________________________

ImmuneAssault

ImmuneAssault

PNH (hemolysis)

PNH (hypoplasia)

Stromal cellDysregulation,ImmuneAssault

What is Complement?What is Complement? Complement is a group of proteins that are part Complement is a group of proteins that are part

of our immune system.of our immune system. Complement circulates in an inactive form.Complement circulates in an inactive form. A little bit of complement is always being A little bit of complement is always being

activated spontaneously, especially at night.activated spontaneously, especially at night. Many different events can activate complement Many different events can activate complement

including trauma, infection, stress, etc.including trauma, infection, stress, etc. Complement will attack certain bacteria by Complement will attack certain bacteria by

making pores in the surface of the bacteria.making pores in the surface of the bacteria. In PNH, activated complement will attack red cells In PNH, activated complement will attack red cells

causing them to “lyse” (burst)causing them to “lyse” (burst)

Terminal Complement Activation Terminal Complement Activation Renders RBCs Susceptible to LysisRenders RBCs Susceptible to Lysis

Normal RBCsNormal RBCs PNH RBCPNH RBC

Intact RBCIntact RBC

ComplementComplementActivationActivation

Lysed PNH RBCs and free hemoglobin in the plasmaLysed PNH RBCs and free hemoglobin in the plasma

Chronic HemolysisChronic Hemolysis

CD59CD59

What happens when red cells lyse?What happens when red cells lyse?

The red cells are destroyed - anemiaThe red cells are destroyed - anemia Hemoglobin is released into the plasma Hemoglobin is released into the plasma

(the fluid part of blood)(the fluid part of blood) Some of the hemoglobin passes through Some of the hemoglobin passes through

the kidneys and into the urine leading to the kidneys and into the urine leading to the dark color of the urinethe dark color of the urine• Loss of ironLoss of iron• May lead to kidney damage in the long runMay lead to kidney damage in the long run

Free hemoglobin binds nitric oxideFree hemoglobin binds nitric oxide• What is nitric oxide?What is nitric oxide?

What is nitric oxide?What is nitric oxide? A gas produced by the body to regulate smooth A gas produced by the body to regulate smooth

muscle cells.muscle cells. An increase in free nitric oxide causes smooth An increase in free nitric oxide causes smooth

muscle cells to relax. A decrease causes smooth muscle cells to relax. A decrease causes smooth cells to contract.cells to contract.

Smooth muscle cells are in many tissueSmooth muscle cells are in many tissue• Blood vessel walls: ischemia, impotenceBlood vessel walls: ischemia, impotence• Esophagus and GI tract: esophageal spasm, Esophagus and GI tract: esophageal spasm,

reflux, abdominal painreflux, abdominal pain

What about thrombosis (blood clots) in What about thrombosis (blood clots) in PNH?PNH?

Blood clots are a presenting sign Blood clots are a presenting sign in 10-20% of patients with PNH.in 10-20% of patients with PNH.

Can occur in up to 40% of patients Can occur in up to 40% of patients with PNH.with PNH.

Occur in unusual locations – veins Occur in unusual locations – veins of the liver (Budd-Chiari of the liver (Budd-Chiari syndrome), spleen, brain, and syndrome), spleen, brain, and skin.skin.

Associated with a very bad Associated with a very bad prognosisprognosis

Cause of these blood clots is Cause of these blood clots is unknown – possibly related to unknown – possibly related to complement activation.complement activation.

Mesenteric / splenic

18%

Hepatic / portal

16%

PE

7%

Cerebral

6%

Superficial

4%

Arterial / CVA

14%

Arterial / MI

2% DVT: leg

18%

DVT: other

15%

The clinical picture of PNHThe clinical picture of PNH

Hemolysis due to complement activationHemolysis due to complement activation• Anemia and fatigueAnemia and fatigue• Hemoglobinuria, kidney damageHemoglobinuria, kidney damage• Nitric oxide trapping >> Esophageal spasm, Nitric oxide trapping >> Esophageal spasm,

abdominal pain, pulmonary hypertension, abdominal pain, pulmonary hypertension, impotence, fatigue?impotence, fatigue?

Thrombosis – Cause of blood clots is still Thrombosis – Cause of blood clots is still unknownunknown• Unusual sites of blood clotsUnusual sites of blood clots

Bone marrow failureBone marrow failure• Decreased blood counts (cytopenias)Decreased blood counts (cytopenias)

Treatment of PNHTreatment of PNH

Who needs to be treated?Who needs to be treated? With what?With what? Does everybody respond?Does everybody respond? What is the long term outlook?What is the long term outlook?

PNH – Who needs to be treated?PNH – Who needs to be treated?

Patients with blood clotsPatients with blood clots Patients with symptomatic anemia from Patients with symptomatic anemia from

hemolysishemolysis Patients with severe bone marrow failurePatients with severe bone marrow failure

Patients with hemolysis who are not symptomaticPatients with hemolysis who are not symptomatic• Can we prevent long term complications such Can we prevent long term complications such

as blood clots, renal failure, or pulmonary as blood clots, renal failure, or pulmonary hypertension?hypertension?

The Treatment “Grey zone”

How do we treat PNH -How do we treat PNH -hemolysishemolysis

TransfusionTransfusion

Iron, folic acidIron, folic acid

SteroidsSteroids

Eculizumab (Soliris)Eculizumab (Soliris)

What does Eculizumab do?What does Eculizumab do?

Quickly and effectively blocks Quickly and effectively blocks complement activation at C5.complement activation at C5.

Blocks hemolysis and related effectsBlocks hemolysis and related effects Stops hemoglobinuriaStops hemoglobinuria Markedly reduces transfusion Markedly reduces transfusion

requirementsrequirements Hemoglobin / hematocrit may not Hemoglobin / hematocrit may not

return to “normal”return to “normal”

Reduction in LDH During Eculizumab Reduction in LDH During Eculizumab Treatment in TRIUMPH and SHEPHERDTreatment in TRIUMPH and SHEPHERD

0

500

1000

1500

2000

2500

3000

0 10 20 30 40 50

TRIUMPH – Placebo/extension

TRIUMPH – SOLIRIS/extension

SHEPHERD - SOLIRIS

Time, Weeks

Lac

tate

Deh

yd

rog

enas

e (U

/L)

Data on file. Alexion Pharmaceuticals; 2007.

TRIUMPH placebo patients switched to SOLIRIS after week 26.All TRIUMPH patients entered the long-term extension study.

SHEPHERD: SHEPHERD: Eculizumab Reduced TransfusionsEculizumab Reduced Transfusions

8

2

8

17

33.5

0 0 0

4

7.5

0

5

10

15

20

25

30

35

40

Overall < 4 Units 4 - 14Units

15 - 25Units

> 25 Units

Med

ian

Un

its

Pac

ked

RB

Cs

1 Year Pre-Treatment

1 Year Post-Treatment

Transfusion Requirements12 Months Prior to Treatment

Young, et al. Blood. 2006;108:971.

(n = 97) (n = 21) (n = 47) (n = 15) (n = 14)

* † ‡

§*

0

2

4

6

8

10

12

14

0 8 16 24 32 40 48 56

Time, Weeks

Me

an

Ch

an

ge

fro

m

Ba

se

line

FA

CIT

-Fa

tig

ue

S

co

re

SHEPHERD: Eculizumab Improved FatigueSHEPHERD: Eculizumab Improved Fatigue

FACIT-F = Functional Assessment of Chronic Illness Therapy‑Fatigue instrument.*P<0.001. P value compared with baseline based on signed rank test.

* ***

*

* * * * *

Imp

rov

eme

nt

Young, et al. Blood. 2006;108:971.

Renal Function with Eculizumab in Different Renal Function with Eculizumab in Different Baseline Populations – 12 MonthsBaseline Populations – 12 Months

Hillmen et al. Blood. 2007 Abstract 3678; High Incidence of Progression to Chronic Renal Insufficiency in Patients with Paroxysmal Nocturnal Hemoglobinuria (PNH).

58.1

23.4

76.9

35.2

71.4

20.5

6.7 5.22.6

0

10

20

30

40

50

60

70

80

90

Segment of PNH Population

Pro

po

rtio

n o

f P

ati

en

ts (

%)

P<0.001 P=0.02 P<0.001

No Change Improvement Worsening

Overall(n=179)

Stage 1 – 2(n=77)

Stage 3 - 5(n=39)

Change in BNP during eculizumab treatmentChange in BNP during eculizumab treatment

PHT with NT-proBNP ≥160 pg/mL1

Eculizumab vs placebo (P<0.001)Eculizumab vs placebo (P<0.001)

50% reduction50% reduction

14% increase14% increase

BaselineBaseline BaselineBaselineWeek 26Week 26 Week 26Week 26

52.5

39.4

26.3

43.8

0

10

20

30

40

50

60

Placebo EculizumabTreatment group: TRIUMPH (n=73)

Pro

po

rtio

n o

f p

ati

en

ts

wit

h e

vid

en

ce

of

PH

T

1Machado RF et al. JAMA 2006; 296: 310-318; Hill A et al. Blood (ASH Annual Meeting Abstracts) 2008; 112: abstract 486

What eculizumab does not doWhat eculizumab does not do

Probably does not help bone marrow Probably does not help bone marrow failure (improve other low blood failure (improve other low blood counts)counts)

Completely correct anemiaCompletely correct anemia Teach you how to play the violin if Teach you how to play the violin if

you have never played beforeyou have never played before

Downside of Eculizumab treatmentDownside of Eculizumab treatment

Increased risk of meningococcal infectionsIncreased risk of meningococcal infections• All patients must be vaccinatedAll patients must be vaccinated• All patients educated on signs and symptoms of All patients educated on signs and symptoms of

meningitis and what to domeningitis and what to do• All patients given cards describing thisAll patients given cards describing this

CostCost Possible coating of red cells with C3 Possible coating of red cells with C3

complement leading to their destruction complement leading to their destruction (extravascular) and anemia(extravascular) and anemia

InconvenienceInconvenience• Must be given intravenously every 12-14 daysMust be given intravenously every 12-14 days

How do we treat or prevent How do we treat or prevent blood clots?blood clots?

Coumadin prophylaxisCoumadin prophylaxisAcute treatment with lytic agents (clot busters)Acute treatment with lytic agents (clot busters)Anticoagulation therapyAnticoagulation therapyBone marrow transplantationBone marrow transplantationEculizumabEculizumab

Effect of Eculizumab on Effect of Eculizumab on ThrombosisThrombosis

92% Fewer thrombotic events with SOLIRIS 92% Fewer thrombotic events with SOLIRIS treatmenttreatment

There were fewer thrombotic events with SOLIRIS treatment than during the same period of time prior to treatment.

Hillmen P, et al. Blood. 2007;110: 4123-4128

39

3

05

1015202530354045

Pre-SOLIRIS Treatment SOLIRIS Treatment

Th

rom

bo

tic

Eve

nts

(#)

P=0.0001

How do we treat bone marrow failure?How do we treat bone marrow failure?

Stimulating agents such as erythropoietinStimulating agents such as erythropoietin

Immunosuppressive agents (ATG, Immunosuppressive agents (ATG, cyclosporine A)cyclosporine A)

Bone marrow transplantationBone marrow transplantation

Where are we going?Where are we going? Improve current therapyImprove current therapy

• Oral eculizumabOral eculizumab• Increase treatment intervalsIncrease treatment intervals

Find other ways to inhibit complementFind other ways to inhibit complement Understand how PNH cells take over the bone Understand how PNH cells take over the bone

marrow so we can reverse this process (Restore marrow so we can reverse this process (Restore normal stem cells)normal stem cells)

Gene therapyGene therapy Stem cell transplantsStem cell transplants