Suspect Hereditary Thrombocytopenia:Familial history of thrombocytopenia, especially parent-child or maternal uncle-nephew. Lack of platelet response to autoimmune thrombocytopenia therapies. Diagnostic features on smear such as abnormal size platelets, absence of platelet alpha granules, Dohle-like bodies or microcytosis. Bleeding out of proportion to the platelet count. Onset at birth. Associated features such as absent radii, mental retardation, renal failure, high tone hearing loss, cataracts or the development of leukemia. Persistence of a stable level of thrombocytopenia for years. Some patients may present with petechial purpura, cranial hematoma or recurrent rectorrhagia

1. Hematopoietic Stem Cell
Transplantation in
Platelet Disorder
Amir Abbas Hedayati-Asl
Hematologist, Oncologist & Ped. Stem Cell Transplantation
Cancer Stem Cell Group
Stem Cell Biology and Technology Department, Royan Institute

2. Suspect Hereditary Thrombocytopenia
• Familial history of thrombocytopenia, especially
parent-child or maternal uncle-nephew.
• Lack of platelet response to autoimmune
thrombocytopenia therapies.
• Diagnostic features on smear such as abnormal size
platelets, absence of platelet alpha granules, Dohle-
like bodies or microcytosis.
• Bleeding out of proportion to the platelet count.
• Onset at birth.
• Associated features such as absent radii, mental
retardation, renal failure, high tone hearing loss,
cataracts or the development of leukemia.
• Persistence of a stable level of thrombocytopenia for
years. Some patients may present with petechial
purpura, cranial hematoma or recurrent rectorrhagia.

3. HSCT & Platelet Disorder
• Wiskott-Aldrich Syndrome (WAS)
• Congenital Amegakaryocytic
Thrombocytopenia (CAMT)
• Paroxysmal Nocturnal Hemoglobinuria
(PNH)
• Glanzmann Thrombasthenia (GT)

4. Wiskott-Aldrich syndrome
• A rare X-linked recessive disorder (incidence, 1-
10:1 million) characterized by bleeding secondary
to micro-thrombocytopenia as well as platelet
dysfunction, defective lymphocyte function
associated with recurrent infections, eczema,
autoimmune manifestations, and later in life
an increased incidence of lymphoma.

5. Wiskott-Aldrich syndrome
• The classic WAS phenotype manifests itself as
early as the neonatal period with petechiae,
bruises, bloody diarrhea, and infections such as
purulent otitis media, pneumonia, and eczema.
• In classic WAS, mean platelet volume is 3.8 to 5.0
fL compared with 7.0 to 10.5 fL in healthy subjects.
• In general, affected patients demonstrate both
cellular and humoral immunodeficiency leading to
recurrent bacterial, viral, and fungal infections.

6. Hematopoietic Stem-Cell Transplantation
in Wiskott-Aldrich syndrome
• The prognosis of classic WAS with a complete
absence of WASP expression in the absence of
hematopoietic stem-cell transplantation (HSCT) is
poor.
• Two major high-risk groups have been identified:
Patients with autoimmune manifestations
Those with severe bleeding
• HSCT is the only curative approach to WAS
providing correction of the immunodeficiency and
platelet disorder when appropriate myeloablative
and immunoablative conditioning regimen is used.

7. Hematopoietic Stem-Cell Transplantation
in Wiskott-Aldrich syndrome
• Patients with matched sibling or parent donors
(MSD) and matched unrelated donors (URD)
exhibit the highest survival rates up to 80%,
especially if transplantation occurs at an early
age with a URD.
• In the absence of a compatible donor, the use
of a mismatched related donor (MMRD) is
associated with a significantly lower survival
rate.

8. Hematopoietic Stem-Cell Transplantation
in Wiskott-Aldrich syndrome
• Conditioning Regimen consisting of:
• Busulfan (16 or 20 mg/kg total dose)
• Cyclophosphamide (200 mg/kg total dose)
in accordance with the EBMT guidelines.

9. Hematopoietic Stem-Cell Transplantation
in Wiskott-Aldrich syndrome
• In vivo immunosuppression:
anti–LFA-1 monoclonal antibodies with or
without anti-CD2)
alemtuzumab monoclonal antibodies,
antithymocyte globulin
patients receiving a URD and MMRD HSCT

10. Other Regimens:
• Fludarabine (150 mg/m2 total dose)
• Melphalan (140 mg/m2total dose).
• T-cell depletion use in all the MMRD in
URD.

12. Autoimmune manifestations after HSCT
• Patients developed autoimmune manifestations after
HSCT independently of cGVHD,autoimmune
manifestations consisted:
– autoimmune thrombocytopenia
– autoimmune hemolytic anemia
– neutropenia
– vasculitis
– inflammatory bowel disease
– pericarditis
– Addison disease
– autoimmune hypothyroidy
• Autoimmune manifestations appeared at a median of
1.5 years after HSCT

13. Sequelae
• Sequelae resulted either from irreversible
tissue damage that had taken place before
HSCT or because of HSCT complications
such as cGVHD, autoimmunity, or severe
infections in splenectomized patients.
• Sequelae were largely due to damage
before HSCT.
• Their frequency was highest in patients who
underwent an HSCT from a URD or MMRD
donor.

14. Splenectomy
• The impact of splenectomy, relationship
between the degree of chimerism and
autoimmune manifestations following
HSCT, immune reconstitution, as well as
any other event seriously affecting the
long-term outcome were also considered.

15. Congenital amegakaryocytic
thrombocytopenia
• Congenital amegakaryocytic thrombocytopenia (CAMT)
is a rare autosomal recessive bone marrow failure
syndrome that presents with severe thrombocytopenia
which can evolve into aplastic anemia and leukemia.
• The disorder is expressed in infancy with or without
physical anomalies.
• It is often recognized on day 1 of life or at least within
the first month. It is often initially confused with fetal and
neonatal alloimmune thrombocytopenia, but the neonate
fails to improve and responds only to platelet
transfusion.

16. CAMT
• The cause for this disorder appears to be
a mutation in the gene for the
thrombopoeitin (TPO) receptor, c-Mpl,
despite high levels of serum TPO.
• Eventually, a diagnostic bone marrow is
performed which can be technically
difficult in a neonate.

17. Differential Diagnosis for:
severe CAMT
• Thrombocytopenia with absent radii (TAR)
• Wiskott-Aldrich syndrome (WAS)
• The primary treatment for CAMT is bone
marrow transplantation. HSCT is the only
thing that ultimately cures this genetic
disease.

18. Classification
• Proposed in 2005 supported by several other reports based on the
course on outcome of the disease as follows;
• Type I—early onset of severe pancytopenia, decreased bone marrow
activity and very low platelet counts. In this group, there is complete
loss of functional c-Mpl. Median platelet count is usually 21 × 109/L or
below.
• Type II—milder form with transient increases of platelet counts up to
nearly normal values during the first year of life and an onset of bone
marrow failure at age 3 to 6 years or later. In this group, there are
partially functional receptors for the c-Mpl gene. Median platelet count
is usually 35 × 109/L to 132 × 109/L.
• Type III—there is ineffective megakaryopoeisis with no defects in the
c-Mpl gene.

19. Prognosis
• Prognosis of CAMT patients is poor, because
all develop in childhood a tri-linear marrow
aplasia that is always fatal when untreated.
• Thirty percent of patients with CAMT die due
to bleeding complications and 20% -due to
HSCT if it has been done.

20. Treatment
• The primary treatment for CAMT is bone marrow
transplantation. HSCT is the only thing that ultimately cures
this genetic disease.
• Children and their family members should be human leukocyte
antigen (HLA)-typed to identify possible matched related
donors.
• Siblings that are heterozygous for a c-mpl mutation may have
abnormal megakaryocytes despite normal peripheral platelet
counts, and usually a sibling can be used as a donor.
• If a matched sibling is not available, transplantation may still
be necessary, especially when marrow failure ensues, but
reported outcomes using matched unrelated donors have
been poor and rates of graft failure are high.
• Newer modalities are on the way, such as TPO-mimetics for
binding towards partially functioning c-Mpl receptors and gene
therapy.

21. Paroxysmal nocturnal hemoglobinuria
(PNH)
• A rare clonal blood disorder that manifests with hemolytic
anemia, bone marrow failure, and thrombosis.
• Many of the clinical manifestations of the disease result from
complement-mediated intravascular hemolysis.
• Allogeneic bone marrow transplantation is the only curative
therapy for PNH.
• Eculizumab, a monoclonal antibody that blocks terminal
complement activation, is highly effective in reducing
hemolysis, improving quality of life, and reducing the risk for
thrombosis in PNH patients.
• Insights into the relevance of detecting PNH cells in PNH and
other bone marrow failure disorders are highlighted, and
indications for treating PNH patients with bone marrow
transplantation and eculizumab are explored.

22. Glanzmann Thrombasthenia
• Glanzmann thrombasthenia (GT; Glanzman,
1918) is a rare autosomal recessive bleeding
disorder caused by either qualitative or
quantitative abnormalities of the membrane
glycoprotein (Gp) IIb/IIIa complex (Nurden &
Caen, 1974)

23. Glanzmann Thrombasthenia (GT)
• Bleeds in GT are variable and may be severe and
unpredictable. Bleeding not responsive to local and
adjunctive measures, as well as surgical procedures, is
treated with platelets, recombinant activated factor VII
(rFVIIa), or anti-fibrinolytics, alone or in combination.
• Although platelets are the standard treatment for GT, their
use is associated with the risk of blood-borne infection
transmission and may also cause the development of
platelet antibodies (to human leukocyte antigens and/or
αIIbβ3), potentially resulting in platelet refractoriness.

24. rFVIIa effectiveness in GT
• Currently, where rFVIIa is approved for use in GT, this is mostly
for patients with platelet antibodies and/or a history of platelet
refractoriness.
• The mechanisms underpinning rFVIIa effectiveness in GT have
been studied. At therapeutic concentrations, rFVIIa binds to
activated platelets and directly activates FX to FXa, resulting in
a burst of thrombin generation.
• Thrombin converts fibrinogen to fibrin and also enhances GT
platelet adhesion and aggregation mediated by the newly
converted (polymeric) fibrin, leading to primary hemostasis at
the wound site.
• In addition, thrombin improves the final clot structure and
activates thrombin-activatable fibrinolysis inhibitor to decrease
clot lysis.

25. Stem cell transplantation
• curative but has previously been undertaken with
full intensity conditioning regimens, with the
potential attendant late effects (infertility, growth
retardation and risk of secondary malignancy).
• SCT technology is, however, a changing field and
the toxicities associated with reduced intensity
conditioning (RIC) together with an increased pool
of closely matched donors from volunteer panels
has lead to a widening of the group of patients in
whom it is possible to perform a SCT with a
reduction in morbidity/mortality.

26. Indications
• A literature search showed 18 previously reported cases
of Glanzmann thrombasthenia treated with allogeneic
hematopoietic stem cell transplant.
• The indications for SCT in GT have included severe
clinical history and/or the development of anti-platelet
antibodies [either anti- Gp IIb/IIIa or against other
epitopes, such as human leucocyte antigen (HLA) or
human platelet antibody (HPA) molecules] rendering the
patient refractory to platelet transfusions (Belluci et al,
2000).
• In these patients, the risk of life threatening
haemorrhage is thought to out-weigh the mortality from
allogeneic transplantation.

27. Preparative Regimen
• Reduced intensity conditioning:
 Fludarabine 30 mg/m2 for 5 d (days -7 to -3)
 Alemtuzumab 0.2 mg/kg for 5 d (days -8 to -4)
 Melphalan 140 mg/m2 24-h prior to stem cell infusion
• Conventional conditioning:
 Busulphan 16 mg/m2 oral preparation over 4 d (day -9
to -5)
 Cyclophosphamide 200 mg/kg IV over 4 d (day -5 to
day -2)

28. Stem cell transplantation
• HSCT is considered a curative treatment for
this disease, but a balance must be struck
between the morbidity/mortality of
transplantation and its benefits.
• To date, several patients with GT have been
successfully transplanted .
• Remarkably, all these patients were children,
except for one adult patient with GT who
underwent HSCT due to a concomitant
diagnosis of acute myeloblastic leukemia

29. Stem cell transplantation
• The HSCT cases reported to date were carried
out in children and young adults with GT and
serious bleeding symptoms, both with and
without anti-platelet antibodies, using bone
marrow, umbilical cord, or peripheral blood
stem cells .
• Most of these patients had HLA-identical
relatives, although a few have undergone non-
family-related donor transplantation

30. Morbidity and Mortality
• Adult patients tend to present higher morbidity and
mortality after transplantation than children,
including more severe GvHD. In spite of partial T-
cell depletion, the patient developed severe cGvHD
accompanied by frequent hospitalizations, use of
medical resources, poor quality of life, and death by
infectious complications.
• In view of the patient’s outcome, we should highlight
that HSCT did improve neither the patient’s quality
of life nor her life expectancy.

31. conditioning regimen myeloablative:
16 mg/kg busulfan in 4 days and
120 mg/kg cyclophosphamide in 3 days
Prophylaxis against GVHD included
cyclosporine and short-term methotrexate.
The patient received 4.2 ×108/kg body weight
non-manipulated peripheral
blood mononuclear cells (5.8 ×106/kg CD34+
cells).

32. Important
• SCT have previously been limited to full
intensity myeloablative conditioning
regimens.
• SCT should be considered as a potential
treatment for children with GT with a
severe bleeding phenotype and/or platelet
refractoriness.

33. In summary
• while research in the gene therapy area for GT is ongoing ,
HSCT is still the only currently available procedure to cure GT
It is indicated in cases with recurrent life-threatening bleeding
complications, particularly if patients are refractory to platelet
transfusions.
• Transplantation should be performed preferably in childhood
given the fewer risks of associated complications, mainly
GvHD and platelet refractoriness.
• In adults, HSCT should be assessed on an individual basis
and the risk of transplantation complications should be
balanced against the risk of bleeding problems of GT and the
ability to control bleeding with the available therapy.

34. In summary
• SCT from an HLA-matched donor is a appropriate
therapeutic option after careful consideration of the
risks and benefits involved in patients with severe,
persistent and life-threatening haemorrhages, and in
those who develop alloantibodies, thus leading to a
state of refractoriness to platelet transfusion.
• It is possible to have durable engraftment with either
conventional or RIC (with the potential for reduced
late effects), with the selection of the preparative
conditioning regimen used being dependent on the
source of stem cells.