THROMBOTISCHE MIKROANGIOPATHIE – PATHOPHYSIOLOGIE-BASIERTE

THERAPIEOPTIONEN

Paul KNÖBL Medizinische Universität Wien

Klinik für Innere Medizin 1, Abteilung für Hämatologie und Hämostaseologie Allgemeines Krankenhaus der Stadt Wien

paul.knoebl@meduniwien.ac.at

TMA: Leitsymptome

•  Coombs-­‐nega,ve,  hämoly'sche  Anämie  mit  Erythrozytenfragmen,erung  

•  Thrombozytopenie  durch  verstärkte  Plä?chenaggrega,on  und  –verbrauch  

•  Störung  der  Mikrozirkula,on    durch  plä?chenreiche    Mikrothromben  

•  Diffuse  Organfunk'ons-­‐  störung  (Gehirn,  Niere,  Herz,    Lunge,  Darm,  etc.)  

Klassifikation der TMA (i) Art der TMA Pathophysiologie

Thrombotisch-thrombopenische Purpura (TTP) Schwerer ADAMTS13-Mangel

Kongenitale TTP (Upshaw-Schulman Syndrom) ADAMTS13-Genmutationen

Erworbene TTP (M.Moschcowitz) Anti-ADAMTS13 Antikörper

Hämolytisch-urämisches Syndrom (HUS)

Kongenitales HUS Komplementsystem-Genmutationen

Erworbenes HUS Autoantikörper gegen

Komplementbestandteile Unbekannte Ursachen

Diarrhoe-/Shigatoxin-assoziiertes HUS Toxine

Knöbl, Hämostaseologie 2013

Klassifikation der TMA (ii) Art der TMA Pathophysiologie

Sekundäre TMA

Infektionen Medikamente Organtransplantationen

unbekannt. Endothelzell-Schädigung

Andere TMA-Formen

Schwangerschafts-assoziiert: HELLP EPH-Gestose

unbekannt

Systemerkrankungen System.Lupus erythematodes Antiphospholipid-Antikörper Syndrom Vaskulitis Maligne Hypertension

unbekannt

Knochenmarks-Karzinose Infiltration mit malignen Zellen

Eli Moschcowitz, Arch Intern Med 1925; 36: 89–93 Reprint in: Mt Sinai J Med. 2003 Oct;70(5):352-5

TTP: Erstbeschreibung

Endothelzelle  

 von  Willebrand  Factor  

UL  VWF  Mul'mere  

ADAMTS13  

 normales  VWF  Mul'merenmuster  

bei  stark  verminderter  ADAMTS13-­‐    Ak,vität:    

(kongenitaler  Mangel  oder    Autoan'körper)  

=>  UL-­‐VWF  MM  persis,eren    

spontane  Plä?chenaggrega,on  in  Situa,onen  mit  erhöhten  Blut-­‐

scherkräXen  

Thrombozyten-­‐  aggrega'on  

TTP: Pathogenese

Häufigkeit:  1,0  -­‐  1,5  Fälle  /  100.000  Kinder  und  Jugendliche  unter  16  Jahre  OX  Kinder  und  Jugendliche  zwischen  1  und  5  Jahren    Klinik:  TMA-­‐typische  Laborkonstella,on  Nierenversagen  steht  im  Vordergrund  aber  häufig  auch  andere  Organschäden      Diagnos'k:  Manchmal  Veränderungen  im  Komplementsystem  OX  keine  spezifischen  Abnormalitäten  feststellbar;  klinische  Diagnose.    

Hämolytisch-urämisches Syndrom (HUS):

Diarrhoe-­‐assoziiertes  HUS:  Enterohämorrhagische  Infek'onen:  

 Shiga-­‐  oder  Verotoxin  bildende  Keime:      EHEC:  E.Coli,  v.a.  Serotyp  O157:H7,  Shigella  

Outbreaks    Keine  spezifische  Diagnos,k  verfügbar.        

Hämolytisch-urämisches Syndrom (HUS):

„atypisches“  HUS:      ohne  Diarrhoe    

Ursachen:    Medikamente,  Transplanta,onen,  Infek,onen,  manchmal  spontan    

Manchmal  (-­‐50%)  assoziiert  mit  Veränderungen  im  Komplementsystem:  •  zahlreiche  Muta'onen/Polymorphismen  bekannt:    (Faktor  H,  Faktor  H  related  Protein  

1  ,  Faktor  I,  MCP  (CD46),  Faktor  B  und  Thrombomodulin,  C3)    führen  zu  einer  verstärkten  Ak,vierung  des  Komplementsystems  (alterna,ver  Weg)  und  nachfolgender  Zellschädigung.    

=  familiäres  /  kongenitales  /  hereditäres  /  chronisch  relapsierendes  HUS      

•  Autoan'körper  gegen  Faktor  H  (oder  andere  Komplementbestandteile),  meist  in  Kombina,on  mit  einer  Muta,on  des  Faktor  H  related  Protein  1  und  3    

=erworbenes  /  sporadisches  HUS    

Trotz  Therapie  hohe  Rate  von  terminalem  Nierenversagen  und  anderen  chron.  Organschäden  

Hämolytisch-urämisches Syndrom (HUS):

Diagnostik bei TMA (i)

Ziel Methoden

Hämolyse Hämoglobin, Erythrozytenzahl, Indizes, Retikulozyten, Fragmentozyten

LDH, Haptoglobin, freies Hämoglobin, Bilirubin Coombs Test

Thrombopenie Thrombozytenzahl, Immature platelet fraction

Anamnese Frühere und andere Erkrankungen, auslösende Ursachen (Tumore,

Infektionen, Systemerkrankungen, Transplantation, Schwangerschaft, Medikamente, Chirurgie, etc.), Familienanamnese

Knöbl, Hämostaseologie 2013

Diagnostik bei TMA (ii)

Ziel Methoden

Erfassung von Organschäden

Gehirn   Zerebrale CT, Perfusions-MRT, EEG, S100 beta, NSE neurokognitive Testung  

Nieren   Serum-Kreatinin, glomeruläre Filtrationsrate, Harnmengen  

Herz   EKG, Troponin, NT-proBNP, Echokardiographie  

Lunge   Sauerstoff-Sättigung, Gasaustausch, Lungenröntgen, HR-CT  

Blutgerinnung   Gerinnungstests, Antiphospholipid-Antikörper  

Pankreas   Glukose, Serum Amylase und Lipase  

Diagnostik bei TMA (iii)

Ziel Methoden

Spezifische Diagnostik:

Generell:  Biobank, Proben für event. Studien

Blutgruppe, Schwangerschaftstest, Virologie (HIV, Hepatitis B and C) Harnanalysen, Schilddrüsenfunktion  

TTP:  ADAMTS13-Aktivität, -Antigen, Anti-ADAMTS13 Antikörper und –inhibitor

ADAMTS13 Genanalyse  VWF:Ag, -RiCo, -CBA, -Multimerenkomposition,

HUS:  Bakteriologie, Toxin-Nachweis (E.Coli, shigella, etc.)

Komplement C3, C4, CH50, Terminales Komplement Komplement-Faktor-Genanalysen  

Etablierte Therapieoptionen bei TMA Therapie Indikation Mechanismus

Plasma-Austausch Initiale Therapie bei allen Formen der TMA

Elimination von Autoantikörpern, Immunkomplexen,

UL-VWF MM, Sludge Zufuhr von

ADAMTS13 u.normalem VWF

Plasma-Infusion Kongenitaler Mangel (ADAMTS13, Komplement,…)

Zufuhr von ADAMTS13, Komplement,…

Corticosteroide Autoantikörper (ADAMTS13, Komplement,…) Immunsuppression

Rituximab Autoantikörper (ADAMTS13, Komplement,…) Immunsuppression

Splenektomie Refraktäre TTP Elimination von Memory- und T-Zellen?

Supportive Therapie Erythrozytentransfusion,

Intensivstation Nierenersatztherapie

Knöbl, Hämostaseologie 2013

Humanisierter Maus Antikörper gegen CD20

Zerstörung von B-Zellen

Etabliert für CD20-pos. maligne Lymphome

Etabliert für verschiedene Autoimmunerkrankungen

Hoch effiziente Autoantikörper-Elimination bei TTP

95 % komplette Remissionen innerhalb von 1-3 Wochen

STAR Trial terminiert (langsames Enrollment), zur Zeit keine anderen

kontrollierten klinischen Studien

Knöbl et al, 2008; Froissard et al, 2012; Scully et al, 2011

Rituximab bei TTP

Alternative Therapieoptionen bei TMA

Therapie Indikation Mechanismus

Immunomodulatoren (Vincristin, MMF, Cyclosporin, Cyclophosphamid)

Autoantikörper (ADAMTS13, Komplement,…) Immunsuppression

Anti-Plättchen Medikamente (ASS, Clopidogrel, Prasugrel, Ticagrelor)

TMA mit schweren Mikrozirkulationsstörungen

Hemmung der Plättchenaggregation

Experimentelle Therapieoptionen Therapie Indikation Mechanismus

Rekombinantes ADAMTS13

Kongenitaler ADAMTS13 Mangel Zufuhr von ADAMTS13

Rekombinantes ADAMTS13 Autoimmun-TTP ? Zufuhr von ADAMTS13 zur

Neutralisierung der Antikörper

Caplacizumab Akute TTP-Schübe Blockade der VWF A1 Domänen, Kompetition mit GP Ib/IX

ARC1779 Akute TTP-Schübe Blockade der VWF A1 Domänen, Kompetition mit GP Ib/IX

ARC 15105 Akute TTP-Schübe ? Chronische TTP ?

Blockade der VWF A1 Domänen, Kompetition mit GP Ib/IX

Eculizumab aHUS Blockade des Komplementsystems

N-Acetylcystein TTP ? Spaltung der Disulfidbrücken im VWF

•  Verfügbar als Diagnostikum (z.B. anti-ADAMTS13 antibody ELISA)

•  In Entwicklung als Therapeutikum (Baxter AG, Austria)

•  Erste klinische Studien (Phase I)

•  Sehr hilfreich bei kongenitaler TTP –

prophylaktische Behandulng mit 20-40 U/kg alle 2-4 Wochen

- Risiko der Allo-Antikörper Entwicklung

•  Unklare Wirksamkeit bei hochtitrigen

Autoantikörpern.

Interessante in vitro Versuche zur

Errechnung der notwendigen Dosis

zum Überkommen der Antikörper.

Plaimauer et al, 2011

Rekombinantes ADAMTS13

Scherkräfte

ADAMTS13 X X X X X X

Anti – GP Ib Substanzen:

•  VCL Peptid •  Spezifische Proteasen gegen GPIbα: •  bakt. O-Sialylglycopeptid-Endopeptidase •  Metalloproteasen aus Schlangengiften •  Antikörper, Fab Fragmente, or Nanobodies •  GPIb-bindende C-Typ Lektine aus Schlangengiften •  Thrombin-Mutanten •  Aurin-Tricarboxyl-Säure •  “small molecules”, zyklische Peptide

Platelet GPIb complex as a target for anti-thrombotic drug development. Kenneth J. Clemetson, Jeannine M. Clemetson. Thromb Haemost 2008; 99: 473–479

Blockade der GP Ib – VWF Interaktion

Scherkräfte

ADAMTS13 X X X X X X

Anti – VWF A1 Substanzen:

•  ARC 1779 Aptamer

•  ARC 15105 Aptamer

•  ALX 0081 Nanobody (=Caplacizumab)

•  AJW200 Antikörper

•  rGPG 290

Blockade der GP Ib – VWF Interaktion

•  40-Nukleotid DNA/RNA Aptamer

gekoppelt an 20 kDa PEG

•  Selektiert auf hochaffine Bindung an VWF

A1 Domänen

•  Potenter und selektiver kompetitiver

Antagonist der vWF A1 Bindung an

Thrombozyten-GP Ib (Kd ≈ 2 nM)

•  Sterile Lösung für iv. Injektion bzw.

kontinuierliche Infusion

ARC 1779

0

20

30

40

50

60

70

80

90

100

29 36 43 50 57 64

platelets

10

1

10

100

ARC1

779  level

days from start of plasma exchange

(/nL)

(µg/ml)

ARC1

779  

 infusion

 rate

2.0 3.0

bolus

(µg/kg/min) Anti-von Willebrand factor aptamer ARC1779 for refractory thrombotic

thrombocytopenic purpura.

Knöbl P, Jilma B, Gilbert JC, Hutabarat RM, Wagner PG, Jilma-Stohlawetz P.

Transfusion. 2009 Oct;49(10):2181-5.

Männlicher Patient mir refraktärer Autoimmun-TTP St.p. 30x PEX, Splenektomie, Steroide Schwere neurologische und kardiale Beeinträchtigung

Phase 2b randomisierte, multizentrische, doppelblinde

Dosisfindungsstudie bei akuter TMA (NCT00726544)

Vom Sponsor nach Einschluß von 9 Patienten beendet

Statistical analysis. Categorical variables were summarized using fre-

quency counts and percentages. Continuous variables were summarized

using one or more of the following: mean, standard deviation, median, mini-

mum, and maximum, 75th and 90th percentile, ignoring missing data when

applicable. Age at survey, age at start of chronic transfusion therapy, aver-

age weight, average pretransfusion Hb and %HbS, average transfusion vol-

ume, duration of transfusion therapy and predominant transfusion type were

summarized with each patient contributing equally. Weight, pretransfusion

Hb and %HbS, transfusion volume, and days late were also summarized

with each transfusion contributing equally. The probability of pretransfusion

%HbS less than 30% was modeled using generalized estimating equations

to account for the lack of independence induced by multiple transfusions per

subject. The models were used to generate estimates of the odds ratio (OR)

and 95% confidence intervals. Results were considered statistically signifi-

cant if the confidence interval excluded one.

AcknowledgmentsThe authors thank the entire TWiTCH Trial Group (members listed in

‘‘Appendix’’) and Rho Federal Systems Division, Inc. (Nancy Yovetich PhD,

Christopher Woods, Jamie Spencer, Marsha McMurray) for their valuable

contributions to the study.

1St. Jude Children’s Research Hospital, Memphis, Tennessee; 2Rho Inc., ChapelHill, NC; 3Baylor College of Medicine, Houston, Tennessee; 4Emory University/Children’s Healthcare of Atlanta, Atlanta, Georgia; 5Children’s National Medical

Center, Washington, DC; 6Medical University of South Carolina, Charleston, SouthCarolina; 7University of Mississippi Medical Center, Jackson, Mississippi;

8University of Texas Southwestern Medical Center at Dallas, Dallas, TX; 9WayneState University, Detroit, Michigan; 10Children’s Memorial Hospital, Chicago,

Illinois; 11Nemours Children’s Clinic, Jacksonville, Florida*Correspondence to: Banu Aygun, MD, St. Jude Children’s Research Hospital,Department of Hematology, M/S 800, 262 Danny Thomas Place, Memphis, TN

38105-3678E-mail: banu.aygun@stjude.org

Conflict of interest: Nothing to report.

Published online 29 December 2011 in Wiley Online Library(wileyonlinelibrary.com).DOI: 10.1002/ajh.23105

References

1. Adams RJ, McKie VC, Hsu L, et al. Prevention of a first stroke by transfu-sions in children with sickle cell anemia and abnormal results on transcranialDoppler ultrasonography. N Engl J Med 1998;339:5–11.

2. Ohene-Frempong K, Weiner SJ, Sleeper LA, et al. Cerebrovascular accidentsin sickle cell disease: Rates and risk factors. Blood 1998;91:288–294.

3. Adams R, McKie V, Nichols F, et al. The use of transcranial ultrasonographyto predict stroke in sickle cell disease. N Engl J Med 1992;326:605–610.

4. Cohen AR, Martin MB, Silber JH, et al. A modified transfusion program forprevention of stroke in sickle cell disease. Blood 1992;79:1657–1661.

5. Miller ST, Jensen D, Rao SP. Less intensive long-term transfusion therapy forsickle cell anemia and cerebrovascular accident. J Pediatr 1992;120:54–57.

6. Aygun B, McMurray MA, Schultz WH, et alfor the SWiTCH Trial Investigators.Chronic transfusion practice for children with sickle cell anemia and stroke. BrJ Haematol 2009;145:524–528.

7. Adams RJ. Lessons from the stroke prevention trial in sickle cell anemia(STOP) study. J Child Neurol 2000;15:344–349.

8. Lee MT, Piomelli S, Granger S, et al. STOP Study Investigators. Stroke Pre-vention Trial in Sickle Cell Anemia (STOP): Extended follow-up and finalresults. Blood 2006;108:847–852.

9. Adams RJ, Brambilla D. Optimizing primary stroke prevention in sickle cellanemia (STOP 2) trial investigators. Discontinuing prophylactic transfusionsused to prevent stroke in sickle cell disease. N Engl J Med 2005;353:2769–2778.

10. Kwiatkowski JL, Yim E, Miller S, Adams RJ;for the STOP 2 Study Investiga-tors. Effect of transfusion therapy on transcranial Doppler ultrasonographyvelocities in children with sickle cell disease. Pediatr Blood Cancer 2011;56:777–782.

11. Mirre E, Brousse V, Berteloot L, et al. Feasibility and efficacy of chronic trans-fusion for stroke prevention in children with sickle cell disease. Eur J Haema-tol 2010;84:259–265.

12. Hulbert ML, McKinstry RC, Lacey JL, et al. Silent cerebral infarcts occurdespite regular blood transfusion therapy after first strokes in children withsickle cell disease. Blood 2011;117:772–779.

Appendix

TWiTCH Trial investigators and coordinators:TWiTCH Trial investigators and key contributors include the following: Bri-

gitta Mueller and Bogdan Dinu (Baylor College of Medicine, Houston, TX);

Kusum Viswanathan and Natalie Sommerville-Brooks (Brookdale Hospital

Medical Center, Brooklyn, NY); Clark Brown and Betsy Record (Children’s

Healthcare of Atlanta, Atlanta, GA); Matthew Heeney and Meredith Ander-

son (Children’s Hospital Boston, Boston, MA); Janet L. Kwiatkowski, Jeffrey

Olson and Martha Brown, (Children’s Hospital of Philadelphia, Philadelphia,

PA); Lakshmanan Krishnamurti and Regina McCollum (Children’s Hospital of

Pittsburgh, Pittsburgh, PA); Kamar Godder and Jennifer Newlin (Children’s

Hospital of Richmond, Richmond, VA); William Owen (Children’s Hospital of

the King’s Daughters); Stephen Nelson (Children’s Hospitals and Clinics of

Minnesota, Minneapolis, MN); Alexis A. Thompson and Katie Bianchi (Child-

ren’s Memorial Hospital, Chicago, IL); Lori Luchtman-Jones and Sheronda

Brown (Children’s National Medical Center, Washington, DC); Margaret Lee

(Columbia University, New York, NY); Courtney Thornburg (Duke University

Medical Center, Durham, NC); Charles Daeschner and Cynthia Brown (East

Carolina University, Greenville, NC); Sherron Jackson and Lisa Kuisel (Med-

ical University of South Carolina, Charleston, SC); Ramamoorthy Naga-

subramanian (Nemours Children’s Clinic Orlando, Orlando, FL); Cynthia

Gauger (Nemours Children’s Clinic, Jacksonville, FL); Brian Berman and

Mary DeBarr (Rainbow Babies and Children’s Hospital, Cleveland, OH);

Sharon Singh and Antonella Farrell (Schneider Children’s Hospital, New

Hyde Park, NY); Banu Aygun and Eileen Hansbury (St. Jude Children’s

Research Hospital, Memphis, TN); Scott Miller and Kathy Rey (SUNY Down-

state, Brooklyn, NY); Isaac Odame, Nagina Parmar, and Manuella Merelles-

Pulcinni (The Hospital for Sick Children, Toronto ON Canada); Zora R Rog-

ers and Leah Adix (The University of Texas Southwestern Medical Center,

Dallas, TX); Lee Hilliard and Jeanine Dumas (University of Alabama, Bir-

mingham, AL); Michelle Neier and Stephanie Farias (University of Medicine

and Dentistry of New Jersey, New Brunswick, NJ); Ofelia Alvarez and Pat-

rice Williams (University of Miami, Miami, FL); Rathi Iyer and Mary T. Walker

(University of Mississippi Medical Center, Jackson, MS); Hamayun Imran

and Stephanie Durggin (University of South Alabama, Mobile, AL); Elizabeth

Yang (Vanderbilt University, Nashville, TN); Sharada Sarnaik and Mary Mur-

phy (Wayne State University, Detroit, MI).

Initial experience from a double-blind, placebo-controlled,clinical outcome study of ARC1779 in patients with thromboticthrombocytopenic purpuraSpero R. Cataland,1* Flora Peyvandi,2 Pier M. Mannucci,2 Bernhard Lammle,3 Johanna A. Kremer Hovinga,3

Samuel J. Machin,4Marie Scully,4 Gail Rock,5 James C. Gilbert,6 Shangbin Yang,1 Haifeng Wu,1

Bernd Jilma,7 and Paul Knoebl8

Despite advances in our understanding of the pathophysiology of

thrombotic thrombocytopenic purpura (TTP), there remains significant

room for improvement in the treatment of acute TTP. A novel approach

to the treatment of TTP using ARC1779 to target the A1-domain of von

Willebrand Factor (VWF) to prevent the formation of microthombi has

been developed. Preliminary data suggests that blockade of the A1-

domain of VWF by ARC1779 can inhibit VWF activity, resulting in clini-

cally significant improvements in the platelet count and lactate dehy-

drogenase [1–5]. ARC1779 is a nucleic acid macromolecule, or

aptamer, that inhibits the prothrombotic function of VWF by binding to

letters

430 American Journal of Hematology

theA1-domain

ofVWF,blocking

itsinteractio

nwith

the

plateletGPIb

receptor.

Ithas

been

hypothesize

dthatARC1779prevents

the

form

a-

tionofnew

microthrombiin

patie

nts

with

acute

TTP,andmayresultin

shorte

rcoursesofplasmaexchange(PEX)and

fewerend

organ

com-

plic

atio

ns

via

the

more

rapid

inhibitio

nofmicrothrombotic

disease.

Prio

rto

thepremature

closure

ofthestudy,

ninepatie

nts

were

treated

with

eith

erARC1779

ofplacebo

as

an

adjunctto

PEX.Alth

ough

lim-

ited,these

data

support

the

safety

ofthis

targeted

approach

tothe

treatm

ent

ofTTP,providing

the

basis

for

contin

ued

study

of

this

uniqueapproachto

therapy.

Patie

ntenrollm

ent.

Atotalofnine

subjects

(seve

nARC1779,two

Place

bo)were

enrolledatsix

siteswhenthestu

dywasclo

sed.Demographic

andclin

icaldetails

oftheenrolledsu

bjects

are

shownin

Table

I.ADAMTS13

activity

wasava

ilable

from

6/7

ARC1779-tre

atedsu

bjects

andboth

place

bo

subjects.

Clinica

lresp

onse

.Clinica

lresp

onse

criteria

were

ach

ieve

dby4/7

sub-

jects

on

the

ARC1779

arm

,and

0/2

place

bo

subjects

prio

rto

the

end

of

the

14-day

infusio

nperio

d.

For

the

4ARC1779-tre

ated

subjects,

the

median

numberofPEX

proce

dures

toach

ieve

resp

onse

criteria

was

7

(range,

6–9).

Three

ARC1779-tre

ated

patie

nts

did

not

meet

clinica

l

resp

onse

criteria

by14days.

Ofthese

onemettheclin

icalresp

onse

crite-

riaon

Day

17,and

one

additio

nalsu

bject

metthe

criteria

atthe

6-w

eek

follow-up

visit,afte

rjudged

tobe

refra

ctory

toARC1779

afte

r9

days

of

therapyand

rece

iving

treatm

entwith

rituxim

ab,vin

cristine,and

cyclophos-

phamide.Oneadditio

nalARC1779-tre

atedpatie

ntach

ieve

danorm

alplate-

letco

untonDay4,butonDay6PEX

washeld

asapart

ofthetaperin

g

ofPEX

while

the

ARC1779

wasco

ntin

ued

with

outtaperin

ggive

nthatthe

plateletco

untwasnorm

alforonly

2co

nse

cutive

days.

He

beca

me

throm-

bocyto

penic

on

the

following

day

afte

rholding

PEX

for1

day

and

while

rece

ivingARC1779aloneandwasneve

rable

toach

ieve

anorm

alplatelet

countbefore

the

end

ofthe

14-dayinfusio

nperio

ddesp

itethe

resu

mptio

n

ofdaily

PEX.Tw

odays

afte

rthe

disco

ntin

uatio

nofARC1779

(afte

rtaper-

ing

completed,butco

ntin

uing

daily

PEX)the

patie

ntwasnoted

tohave

a

rising

troponin-I

[9.79

and

17.14

ng

mL21on

2co

nse

cutive

days

(norm

al

<0.11

ng

mL21)]

asmeasu

red

inthe

loca

lclin

icallaboratory.

Three

days

afte

rthe

ARC1779

infusio

nwassto

pped

his

troponin-I

remained

eleva

ted

at14.52

ng

mL21and

he

suffe

red

aca

rdiacarre

stand

died.One

ofthe

twoplace

bo-tre

atedpatie

nts

ach

ieve

danorm

alplateletco

untafte

r14daily

PEX

proce

dures,

butthe

otherplace

bo-tre

ated

patie

ntremained

seve

rely

thrombocyto

penic

on

day13,eve

ntually

ach

ievin

ga

norm

alplateletco

unt

atthe

6-w

eekfollow-upvisit

afte

rtherapywith

rituxim

ab.Forthefive

sub-

jects

who

ach

ieve

da

norm

alplateletco

unton

ARC

1779

(inclu

ding

the

subject

who

ach

ieve

da

norm

alplateletco

untbutdid

notmeetresp

onse

criteria

),themediannumberofdaily

PEX

proce

duresto

ach

ieve

aplatelet

countof>1503

109/L

was5(ra

nge,4–14).

ARC1779

conce

ntra

tion

and

VWF

activity.

Seria

lVWF

activity

and

ARC1779co

nce

ntra

tionswere

studiedto

judgetheeffica

cyofARC1779in

term

soffre

eA1domainsasasu

rroga

teforVWFactivity

(Fig.1).The

sedata

demonstra

tedthesu

staine

dsu

ppression

ofVWFactivity

(decre

ase

dava

ilable

A1domain

sites)throug

hou

tthe14-d

ayinfusio

nwith

recove

ryto

norm

alleve

ls

after

thetape

ringand

disco

ntinuation

oftheinfu

sion.

Adve

rseeve

nts.

Subjects

randomize

dto

ARC1779

arm

ofthe

study

exp

erie

nce

dthe

following

serio

us

adve

rseeve

nts:

mentalsta

tus

changes

(2),

seizu

rediso

rder

(1),

catheter-re

lated

thrombosis

(1),

and

catheter-

relatedse

psis

(1).

Thementalsta

tusch

angesin

both

subjects

were

deter-

mined

tonotbe

related

tothe

studydrug.In

the

case

ofthe

firstpatie

nt,

theyoccu

rred30days

afte

rherlast

dose

ofARC1779andin

theco

ntext

of

multip

leacu

teinfarctio

ns

ofthe

cerebralhemisp

heres

and

cerebellum.

Give

nthe

recu

rrentthrombocyto

penia

atthe

time

ofprese

ntatio

n,a

recu

r-

rence

ofTTP

wasfeltto

bethemost

likely

etio

logyoftheacu

teinfarctio

ns

andthesu

bse

quentmentalsta

tusch

anges.

Inthese

condpatie

nt,themen-

talsta

tusch

angesand

ase

izure

diso

rderwere

noted

tooccu

rco

incid

ent

with

arecu

rrentthrombocyto

penia

consiste

ntwith

arecu

rrence

ofTTP.

Imaging

ofhis

brain

by

CT

showed

no

abnorm

alitie

s,and

symptoms

improve

dwith

thereinitia

tionofPEX

therapy.

Intheopinionofthetre

atin

g

physicia

ns,

these

serio

usadve

rseeve

nts

were

notthoughtto

berelatedto

ARC1779,butratherwere

relatedto

thediagnosis

ofTTP

andtherelated

therapy

(catheter-re

lated

complica

tions).

No

serio

us

adve

rseeve

nts

were

reporte

don

the

place

bo

arm

ofthe

study.

No

ARC1779-tre

ated

subjects

TABLE I. Demographic and Clinical Data (Median) at Presentation and Responses to Therapy for all Nine Enrolled Subjects

Median age(range) Sex (M/F)

Race(AA/C)

PretreatmentADAMTS13%a

Platelet count(3109/L) LDH (U/L)

Creatinine(mg dl21)

Clinical response(!14 days)

Immune suppressivetherapy Adverse events

ARC1779 (n 5 7) 44 (33–51) 4/3 3/4 72 (<2.5–100) 16 1,063 (263–1,804) 1.31 (0.8–2.46) 4/7 Corticosteroids (4);Rituximab (1);CSA (1);Vincristine (1)

Mental status changes (2)a;catheter-related Sepsis (1)a;catheter-related DVT (1)a

Placebob(n 5 2) 32, 70 0/2 0/2 <2.5, 42% 16 647, 1,258 4.54, 0.99 0/2 Corticosteroids (1) None

All adverse events reported were judged to not likely be related to the study drug.aFour of 8 ADAMTS13 measurements were obtained after the first PEX procedure but prior to the first dose of ARC1779.bGiven that there were only two subjects in the placebo arm, data for both subjects rather than the median data are presented.

letters

American

Journalof

Hem

atology431

experienced bleeding symptoms including cutaneous purpura or petechiae

during the infusions despite sustained suppression of ‘‘VWF activity’’ in sub-

jects with platelet counts as low as 6 3 109/L.

Despite the premature closure of this study, there are significant observations

that can be made from these nine patients that were enrolled. With the bolus

primed continuous infusion of ARC1779, sustained suppression of VWF activity

(free A1 domain sites) relative to pretreatment activity was achieved. The sup-

pression of VWF activity correlated with plasma concentrations of ARC1779,

and recovered with tapering and discontinuing the ARC1779 infusion. Clinical

responses were also consistent with what has been reported previously with

ARC1779. It is not clear if a more sustained inhibition of VWF activity below the

goal of 10% of baseline VWF activity would improve the efficacy, but it is worth

noting that there were no hemorrhagic complications seen in the pilot study

where the mean VWFactivity during the ARC1779 infusion was 5%.

The most important conclusion that could be drawn from these preliminary

data would be that the drug was well-tolerated by the patients studied. Con-

cern would be justified regarding the potential for bleeding complications

that might arise from inhibiting VWF activity in patients already severely

thrombocytopenic (median platelet count 16 3 109/L at presentation). How-

ever, despite achieving sustained suppression of VWF activity throughout

the continuous infusion of ARC1779, no patient experienced bleeding com-

plications. Despite the absence of any observed bleeding complications,

additional study is required to confirm the safety of sustained reductions to

<10% VWF activity in severely thrombocytopenic TTP patients.

These data suggest that the addition of ARC1779 to PEX may have

decreased the number of exchanges to achieve a normal platelet count, but

with only two patients in the placebo group it is not possible to draw defini-

tive conclusions. It is clear that ARC1779 does not alter the basic disease

process that results in the initiation of microthrombus formation in patients

with TTP, but rather prevents the formation of VWF-mediated microthrombi.

The patient described who achieved a normal platelet count, but developed

a recurrent thrombocytopenia while receiving ARC1779 but holding PEX for

one day provides an illustration of this point. Despite continued therapy with

ARC1779 at the intended dose, the patient clinically deteriorated, developing

recurrent thrombocytopenia consistent with an acute exacerbation of TTP.

Effective suppression of the ADAMTS13 inhibitory antibody via PEX or adju-

vant immune suppressive therapy is still required to achieve a sustained

remission of TTP. With this approach, ARC1779 or a similar agent could pro-

vide more immediate protection until the disease process can be sup-

pressed by PEX and/or immune suppressive therapy.

While limited in number and longitudinal follow-up, these data provide sup-

port for the continued study of VWF A1 inhibition as an adjunct to PEX in

the treatment of TTP. These therapies should however be viewed as protec-

tive agents that do not alter the underlying pathophysiology, and therefore

should be administered as an adjunct to PEX and/or immune suppressive

therapy in patients with acquired TTP.

MethodsStudy methodology. ARC1779-006 was a randomized, double-blinded,

placebo controlled multicenter, international study in patients with TMA with

a planned randomization ratio of ARC1779 to placebo of 3:1(ClinicalTrials.-

gov Identifier: NCT00726544). The objectives of the study were to evaluate:

(1) the safety and tolerability of ARC1779, (2) the concentration-response of

ARC1779 in terms of efficacy and safety related effects, and (3) the ability

of ARC1779 to prevent or minimize short-term neurologic, cardiac, and renal

injury from an acute episode of TTP. The study was intended to enroll 100

subjects, but was terminated prematurely by the sponsor after enrolling nine

subjects for financial reasons.

Eligible subjects included adults 18–75 years of age with a diagnosis of a

TMA (platelet count of <100 3 109/L and microangiopathic hemolytic

anemia without an alternative explanation). Patients with pregnancy-associ-

ated TMA were eligible if no longer pregnant or breast-feeding. Patients with

both initial and relapsed events were eligible. The volume of PEX and

decision regarding adjuvant immune suppressive therapy were left to the

discretion of the treating physician. Subjects randomized to ARC1779

received an initial loading dose of 0.21 mg kg21 followed by a continuous

infusion at a rate of 0.6 mg/kg/min. After each PEX, a repeat loading dose

at 50% of the initial loading dose was administered to rapidly restore

ARC1779 concentrations after the removal of drug by PEX. ARC1779 or

placebo was continued until achieving a clinical response (platelet count

=150 3 109/L on 3 consecutive days) or for a maximum of 14 days. The

infusion (ARC1779 or placebo) was then decreased by 50% on day 11, by

an additional 50% on day 12, and discontinued on day 13. PEX was

tapered at the discretion of the treating physician.

Efficacy was assessed by the serial measurement of complete blood

counts (CBC) and the lactate dehydrogenase (LDH). Bleeding complications

were monitored and reported by the treating physician who reported any

clinical bleeding symptoms and findings including minor skin bleeding, both

during therapy and the planned 6-week follow-up.

1Department of Medicine and Pathology, Ohio State University, Columbus, Ohio;2U.O.S. Dipartimentale per la Diagnosi e la Terapia delle Coagulopatie, A. Bianchi

Bonomi Hemophilia and Thrombosis Center, IRCCS Ca Granda FoundationMaggiore Policlinico Hospital, Milan, Italy; 3Department of Hematology, UniversityHospital Bern, Bern, Switzerland; 4University College London Hospitals, London,United Kingdom; 5Department of Pathology, University of Ottawa, Ottawa, ON,Canada; 6Archemix Corp., Cambridge, Massachusetts; 7Department of Clinical

Pharmacology, Medical University of Vienna, Wien, Austria; 8Department ofInternal Medicine, Medical University of Vienna, Vienna, Austria

Contract grant sponsor: Archemix CorpBernd Jilma and Paul Knoebl are senior authors.

*Correspondence to: Spero R. Cataland, M.D., Department of Internal Medicine,Ohio State University, A361 Starling Loving Hall, 320 W. 10th Ave., 306B Starling

Loving Hall, Columbus, OH 43210E-mail: spero.cataland@osumc.edu

Conflict of interest: SRC, FP, PMM, BL, JKH, SJM, MS, GR, BJ, and PK all servedas consultants to the Archemix Corp. JCG was employed by the Archemix Corp

Published online 29 December 2011 in Wiley Online Library(wileyonlinelibrary.com).DOI: 10.1002/ajh.23106

References

1. Bouchard PR, Hutabarat RM, Thompson KM. Discovery and development oftherapeutic aptamers. Annu Rev Pharmacol Toxicol 2010;50:237–257.

2. Knobl P, Jilma B, Gilbert JC, et al. Anti-vonWillebrand factor aptamer ARC1779 forrefractory thrombotic thrombocytopenic purpura. Transfusion 2009;49:2181–2185.

3. Gilbert JC, DeFeo-Fraulini T, Hutabarat RM, et al. First-in-human evaluationof anti von Willebrand factor therapeutic aptamer ARC1779 in healthy volun-teers. Circulation 2007;116:2678–2686.

4. Diener JL, Daniel Lagasse HA, Duerschmied D, et al. Inhibition of von Willebrandfactor-mediated platelet activation and thrombosis by the anti-von Willebrand fac-tor A1-domain aptamer ARC1779. J Thromb Hemost 2009;7:1155–1162.

5. Jilma-Stohlawetz P, Gorczyca ME, Jilma B, et al. Inhibition of von Willebrandfactor by ARC1779 in patients with acute thrombotic thrombocytopenic pur-pura. J Thromb Hemost 2011;105:545–552.

Figure 1. Shown in the figure above are the median ARC1779 concentrations andfree VWF A1 domains (‘‘VWF activity’’) for the ARC1779-treated patients throughoutthe 14-day dosing period. The number above each data point reflects the number ofsamples studied at each time point. Day 11 and 13 represent the first 50% taperingof ARC1779 and the time of discontinuing ARC1779 respectively.

letters

432 American Journal of Hematology

(Arterioscler Thromb Vasc Biol. 2012;32:00-00)

•  DNA/RNA Aptamer gekoppelt an 40 kDa PEG

•  Selektiert auf hochaffine Bindung an VWF A1 Domänen

•  in vivo PK/PD Studien in Cynomolgus Affen

•  ex vivo Studien in Patienten mit Myokardinfarkt

•  Verschiedene in vitro Studien (Elektronenmikroskop, Flusskammer)

ARC 15105

PK/PD data of ARC 15105 in cynomolgus monkeys

•  Bivalentes 28 kD Nanobody

•  Positive präklinische Daten

•  Potente Inhibition der

Thrombozytenaggregation ohne erhöhtes

Blutungspotential

•  Inhibition von Thrombozytenadhäsion an

ULVWF und Thrombozyten-Stringbildung

•  Potentielle klinische Vorteile bei TTP: •  Verbesserte Effizienz und Sicherheit

•  sc. Gabe

•  Lange Halbwertszeit (48h)

Anti-VWF Nanobody

Conventional antibody

Heavy-chain antibody

VH VL CL

CH1

CH3

CH2 Ablynx’s Nanobody CH3

CH2

Camelidae family has both forms

VHH

VHH

Bivalent anti-VWF

Nanobody

Structure : courtesy of Steyaert et al, VUB

Anti-VWF Nanobody (ALX-0081/ALX-0681)= Caplacizumab

PE

PE 30 days

30 days

1 year follow-up

1 year follow-up

Primary endpoint time-to-response,

defined by recovery of platelets ≥ 150 G/L and confirmation at 48 h by de novo measure of platelet count ≥ 150 G/L and LDH ≤ 2 x ULN

Secondary endpoints • PE frequency and volume •  relapse • exacerbations • mortality • major clinical events •  recovery from signs and

symptoms

Ran

dom

isat

ion

Placebo

anti-VWF Nanobody

1:1

Inclusion criteria • men and women • 18 years or older • clinical diagnosis of TTP,

necessitating PE

Exclusion criteria • platelet count ≥ 100 G/L • severe active infection

indicated by sepsis •  infection with E. coli 0157 or

related organism • anti-phospholipid syndrome,

DIC or congenital TTP • pregnancy or breast-feeding • active bleeding or high risk

of bleeding • uncontrolled arterial

hypertension • chronic anticoagulant

treatment • bone marrow carcinosis • severe liver impairment

n = 110

The TITAN trial: Study Design

•  Intensivstations-Bett suchen (auch bei scheinbar guten Patienten, akute Verschlechterung jederzeit möglich)

•  Organfunktion engmaschig überwachen (Herz, Hirn, Niere)

•  Patient/in geeignet für klinische Studie? (PI anrufen)

•  Citratplasma (8 Röhrchen) gewinnen für weitere Diagnostik (VOR Plasmaaustausch)

•  Venenzugang beurteilen für Plasma-Austauschtherapie eventuell Quinton stechen (KEINE TK!)

•  Plasma-Austausch anmelden

•  Nierenersatztherapie (bei Bedarf)

•  Immunsuppression 100 mg Solu-Dacortin iv.

•  4 Ery-Konz. kreuzen lassen

•  TROTZDEM Differentialdiagnosen aufarbeiten…

Akutmanagement der TMA:

URSACHE  BESEITIGEN  (wenn  möglich)    

PLASMAAUSTAUSCH-­‐Therapie:    immer  noch  1.Wahl  Elimina,on  von  Autoan,körpern,  Thrombozytenaggregaten,  UL-­‐VWF  MM,  Sludge;    Zufuhr  von  ADAMTS13,  normalem  VWF  Plasmaaustausch  gegen  FFP  oder  Octaplas®,  täglich  50-­‐80  ml/kg    Pa,enten  mit  hereditärem  ADAMTS13  Mangel  sprechen  prompt  an    

 (Normalisierung  der  Thrombozyten  nach  1-­‐2  Behandlungen)      

Pa,enten  mit  An'-­‐ADAMTS13  An'körpern  sprechen  zunächst  gut  an  (Thrombozytenans,eg),      dann  oX  aber  Exazerba,on  nach  ca.  1  Woche.  =>  konsequente  Weiterbehandlung  !  

 

Therapiedauer:  bis  Thrombozyten,  LDH,  Organdysfunk,on  und  Klinik  normal,  dann  noch  3  x  mit  verlängerten  Intervallen.  Exazerba,on  nach  zu  früher  Beendigung  häufig!    

 

Behandlungsoptionen für TTP (i):

 KEINE  THROMBOZYTENKONZENTRATE  !!!    

Thrombozytenaggrega'onshemmer    (Clopidogrel,  ASS)  überlegen  bei  prolongiertem  Verlauf,  Zeichen  schwerer  Organdysfunk,on,  häufigen  Relapsen,  auch  wenn  Thrombozytenzahl  niedrig  

Behandlungsoptionen für TTP (ii):

Komplement-­‐Inhibi'on:  Eculizumab  (Soliris®)  

Bei  nachgewiesenen  oder  vermuteten  Autoan'körpern  im  Komplementsystem:  Immunsuppression  (z.B.  Steroide,  Rituximab)  

Symptoma'sche  Therapie:  Nierenersatztherapie  Plasmatherapie  (bei  manchen  kongenitalen  Defekten  promptes  Ansprechen)      Suppor,ve  Maßnahmen  

Behandlungsoptionen für HUS:

Keine  spezifischen  Therapieop'onen  

Absetzen  des  verdäch,gen  Medikaments,  Wechsel  auf  Alterna,vpräparat  

Symptoma,sche  Plasmaaustauschtherapie  (meist  wirkungslos)  

Nierenersatztherapie  

Suppor,ve  Maßnahmen  

 

OX  „spontane“  Besserung  nach  mehreren  Wochen/Monaten  

 

Behandlungsoptionen sekundäre TMA:

Intensivüberwachung / -therapie: •  Schwere Organdysfunktion möglich (Myokardinfarkt, Rhythmusstörungen, Insulte,

Epilepsie, Nierenversagen, Darmischämie,...) Akute Verschlechterung trotz Therapie möglich

Erythrozytentransfusionen: •  Hb Grenzwert nicht definiert (< 7.0 g/dL, höher bei ACS)

Thrombozytentransfusionen: •  NICHT in der Frühphase (Aggravierung der Mikrozirkulationsstörungen möglich).

Blutungsrisiko niedrig, trotz Thrombopenie (außer bei gestörter Hämatopoese – SZT, Virusinfekte, Medikamente)

TVT Prophylaxe: •  LMWH zur Thromboseprophylaxe auch bei niedrigen Thrombozytenwerten.

Infektionsprophylaxe: •  Infektionen (Katheter, Pneumonie, etc.) können akute Verschlechterung der TMA

verursachen. Verschleiert durch Steroid-Therapie.

Supportivtherapie:

Zusammenfassung: •  Die Prognose der TTP konnte durch die Plasmaaustauschtherapie deutlich

verbessert werden, aber Mortalität und Morbidität sind immer noch hoch. Plasmaaustausch ist oft nur eine symptomatische Behandlung.

•  Das heutige Verständnis der Pathophysiologie der TTP eröffnet modernere, zielgerichtete Behandlungsformen: -  Beeinflussung der Plättchen-VWF Interaktion zur Verhinderung der

Organschädigungen in der akuten Phase der Erkrankung -  Unterbrechung des Autoimmunprozesses als kausale Therapie zur

Verhinderung von Relapsen -  Zufuhr von ADAMTS13 als zielgerichtete Substitution bei ADAMTS13

Mangel •  Weniger eindeutige Fortschritte beim HUS, Soliris® bei Komplement-

Überaktivierung

•  Praktisch keine neuen Ansätze bei sekundären TMA-Formen