Hedayati Asl A.

Pediatrics Hematologist & Oncologist

BMT

MAHAK Children’s Cancer Hospital

• Direct action of chemo-radiotherapy

–Nausea, vomiting, diarrhoea, alopecia, pain

–Mucositis

–Haemorrhagic cystitis

• Endothelial dysfunction by conditioning

–Veno-occlusive disease / Capillary leak synd.

Thrombotic microangiopathy / Idiopathic

pneumonia syndrome / Engraftment syndrome

• Drug toxicity (CsA/FK, G-CSF, Antibiotics,)

• Infections

• Immune complications (GvHD, graft failure)

An understanding of the pathogenesis of this

reaction has been obtained via the study of

animal models of GVHD.

The basic requirements for the development

of this disorder were recognized as early as

the 1960s.

Activated Donor T cells damage host

epithelial cells after an inflammatory cascade

that begins after the preparative regimen

GVHD is the major barrier to successful

HSCT

Graft-versus-host disease is a direct result of one of the principal functions of the immune system: the distinction of self from non-self.

In an attempt to treat patients with severe and life-threatening illnesses, immune cells may be transplanted from a non-identical donor to the patient.

These donor (eg, graft) cells may recognize patient (eg, host) cells as foreign, thereby initiating a graft-versus-host reaction which may lead to GVHD .

Characteristics:

The graft must contain immunologically competent cells.

The host must possess transplantation antigens that are lacking in the graft, thereby appearing foreign to the graft; host cells subsequently stimulate donor cells via these specific antigenic determinants.

The host must be incapable of mounting a reaction against the graft for a period of time sufficient to allow graft cells to attack the host.

Since GVHD is primarily a T cell mediated

disease, this discussion of the pathogenesis of

the disorder consists of an overview of the

more important properties and interactions of a

transplanted T cell which may lead to the

disease.

It is important to realize that additional

hematopoietic cells, such as natural killer cells,

also underlie the development of GVHD.

Prior to discussing those aspects of T cell

function relevant to the pathogenesis of GVHD,

it is helpful to first briefly review the major

Histocompatibility Complex (MHC) or HLA (for

Human Leukocyte Antigens) in humans since

these molecules underlie the recognition of

antigen by T cells.

The MHC is highly polymorphic from individual

to individual, and segregates in families in a

Mendelian codominant fashion.

The genes of the HLA locus encode two distinct classes of cell surface molecules, classes I and II.

Class I molecules are expressed on the surfaces of virtually all nucleated cells at varying densities, while class II molecules are more restricted to cells of the immune system, primarily B lymphocytes and monocytes.

There are three different class I (HLA-A, -B, -C) and class II (HLA-DQ, -DR, -DP) antigens. HLA-A, -B and -DR antigens appear to be the most important loci determining whether transplanted cells initiate a graft versus host reaction

DONOR RECIPIENT

• Related/unrelated

• HLA mismatched

• Sex mismatched

• Alloimmunisation

• Source of stem cells

• Age

• Conditioning

regimen

• Prevention of GVHD

Incidence 10 to 80% (median ~ 40%)

Risk factors for the development of acute GVHD include :

Degree of HLA disparity

Increasing age of host

Donor and recipient gender disparity

CMV status of donor and host

Intensity of the transplant conditioning regimen

Peripheral blood stem cell versus bone marrow transplantation

Acute GVHD prophylactic regimen used

Counterpart of graft

versus tumour

effect

Acute <100 days

May be lethal

Chronic >100 days

May be disabling

Clinically significant acute graft-versus-host

disease (GVHD) occurs in 9 to 50 percent of

patients who receive an allogeneic

hematopoietic cell transplant (HCT) from a

genotypically HLA-identical sibling, despite

intensive prophylaxis with immunosuppressive

agents, such as methotrexate, cyclosporine,

tacrolimus, corticosteroids, or antithymocyte

globulin.

Acute GVHD is also common in matched

unrelated donors and in haploidentical related

donors.

Development of moderate (grade II) or severe

(grade III or IV) acute GVHD after HCT is

associated with a significant decrease in

survival. Furthermore, once acute GVHD

occurs, it may not be treatable.

The skin, liver, gastrointestinal tract, and the

hematopoietic system are the principal target

organs in patients with acute GVHD

Epithelial cells of

SKIN: keratinocytes

LIVER: biliary ducts

DIGESTIVE TRACT: enterocytes

« satellite cell necrosis »

(infiltrating immune cell + apoptotic cell)

Skin lesions in a patient with severe acute graft-versus-

host disease (GVHD). There is swelling, generalized

erythroderma, and bullous formation.

Graft versus host disease (GVHD)

Anorexia, nausea

Green watery diarrhea

Abdominal pain, bloody diarrhea

Gastro-duodenal biopsies

Investigators at the University of Minnesota

have described acute GVHD of the upper

gastrointestinal tract characterized by anorexia,

dyspepsia, food intolerance, nausea, and

vomiting.

This syndrome was verified by positive upper

endoscopic biopsies of the esophagus and

stomach.

Cholestatic hepatopathy…

(other causes of hepatopathy: toxicity,

infection, VOD…)

Other symptoms

Fever, eosinophilia …..

Hepatic involvement is manifested by abnormal

liver function tests, with the earliest and most

common finding being a rise in the serum

levels of conjugated bilirubin and alkaline

phosphatase.

This reflects the pathology associated with

liver GVHD: damage to the bile canaliculi,

leading to cholestasis.

However, a rise in the serum concentration of bilirubin or alkaline phosphatase is nonspecific.

In this setting, the most common confounding disorders include:

Hepatic veno-occlusive disease, which is a relatively common toxicity associated with the use of high dose therapy.

Hepatic infections (primarily viral hepatitis).

Effects from the preparatory regimen.

Drug toxicity, including the drugs used for GVHD prophylaxis (cyclosporine and/or methotrexate).

Although less common, acute GVHD can affect the hematopoietic system. Early studies reported that the principal focus of the graft-versus-host reaction occurred in the lymphoid organs of the host. Immune competence was therefore affected, leading to frequent and possibly fatal infectious complications.

In murine models, acute GVHD can affect hematopoiesis, leading to a reduction of precursor hematopoietic cells but not a clear decrease in peripheral blood counts . In humans, the effect of GVHD on the hematopoietic system is usually not dramatic. Persistent thrombocytopenia is a frequent manifestation and a profound drop in the serum concentration of immunoglobulins (such as IgA) may be observed.

The development of thrombotic

microangiopathy following HCT has been

shown to adversely affect the survival of

patients with acute GVHD.

Acute GVHD may also result in decreased

responsiveness to active immunization. One

study, for example, found a less effective

immune response to polio vaccination in

patients with GVHD.

With acute GVHD, the induction of

autoimmune disease occurring in association

with autoantibody production may require the

expression of particular class II haplotypes.

In a murine model of GVHD, for example, the

onset of lupus-like nephritis in animals

producing pathogenic IgG antinuclear

antibodies was dependent upon the MHC

haplotype expressed by the recipients.

There are isolated case reports of patients with

acute and/or chronic GVHD who develop

nephrotic syndrome due to membranous

nephropathy.

Most patients have had stabilization in renal

function and significant reductions in protein

excretion after therapy with steroids and/or

cyclosporine.

Acute GVHD has been traditionally (and arbitrarily) defined as a syndrome occurring during the first 100 days following HCT, with neutrophilengraftment assumed as a condition for the diagnosis.

Early onset or hyperacute GVHD, which was originally seen in allogeneic HCT recipients who did not receive GVHD prophylaxis, has been described as a clinical syndrome that can occur at any time following allogeneic infusion, independent of neutrophil engraftment, and has been associated with the use of alternative HCT donors.

The most severe form of hyperacute GVHD

was described after haploidentical HCT, and

consisted of fever, rash, and massive

noncardiogenic pulmonary edema, often with

renal failure and seizures

Clinical evaluation

The diagnosis of acute GVHD can be readily

made on clinical grounds alone in the patient

who presents with a classic rash, abdominal

cramps with diarrhea, and a rising serum

bilirubin concentration within the first 100 days

following transplantation.

Histologic confirmation may be helpful to

corroborate a clinical impression of possible

acute GVHD.

The skin and gastrointestinal tract are relatively

easy to biopsy.

As previously mentioned, percutaneous liver

biopsy poses a significant risk of major

bleeding since most patients are

thrombocytopenic at the time of GVHD.

Percutaneous transjugular liver biopsy is a

safer alternative if it can be adequately

performed.

Analysis of the pattern of plasma and urine

polypeptides using proteomics has shown promise

in enabling early diagnosis of acute GVHD .

As an example, it has been proposed that a panel

of markers including Interleukin-2 receptor-alpha,

tumor necrosis factor receptor-1, Interleukin-8, and

hepatocyte growth factor can confirm the diagnosis

of acute GVHD at the onset of clinical symptoms

and provide prognostic information independent of

GVHD severity

An early study in experimental animals and

human subjects with biopsy-proven intestinal

GVHD has suggested that imaging of the colon

via 18F-FDG PET scanning may be a sensitive

and specific technique for distinguishing

intestinal GVHD from other competing

diagnoses.

The presence of GVHD remains the most important post-transplant factor influencing outcome following allogeneic HCT. For the period from 100 days to 3 years post-transplant, hazard ratios (HR) for transplantation-related mortality (TRM) increased with increasing grades of acute GVHD:

Grade 0 acute GVHD — hazard ratio (HR) for TRM: 1.0

Grade I — HR 1.5 (95% CI 1.2-2.0)

Grade II — HR 2.5 (95% CI 2.0-3.1)

Grade III — HR 5.8 (95% CI 4.4-7.5)

Grade IV — HR 14.7 (95% CI 11-20)

Conversely, increasing degrees of acute GVHD reduced the risk of relapse:

Grade 0 acute GVHD- hazard ratio (HR) for relapse 1.0

Grade I — HR 0.94 (95% CI 0.8-1.2)

Grade II — HR 0.60 (95% CI 0.5-0.8)

Grade III — HR 0.48 (95% CI 0.3-0.8)

Grade IV — HR 0.14 (95% CI 0.02-0.99)

Can GVHD be prevented? (without an

increase of relapse risk)

What is the best 1st line therapy?

Is it possible to predict the response to

therapy and to avoid evolution to higher

grades of aGVHD?

What about 2nd line treatments?

Can we improve immune reconstitution?

Conditioning therapy activates host

tissues: reduced intensity conditioning

regimen??

Donor T cell response: depletion or

inactivation of donor T cells +++

Effector stage ? To block cytokines???

(mainly used in Tt rather than in prophylaxis)

Target: the 3 phases of aGVHD?

Corticosteroids as first line treatment of

•Why?

Broad inhibition of major mechanisms involved

in GvHD:

T cell apoptosis

Cytokine suppression

Interfering with other cells like macrophages

•Dose?

1 vs 2 mg/kg vs higher doses

« High dose » steroids 2 mg/kg:

primary Tt for more than 25y

Questions:

Higher dose?

Lower dose?

1st line combination of steroid +

other IS treatment?

1st line treatment

•Early response is essential

•Drugs and antibodies:

–Uniform response rates 30-50%,

high rate of

infectious complications

–Drugs:

•MMF; Pentostatin; Rapamycin

–Antibodies:

•ATG, Thymoglobulin, Campath, Etanercept

• Poor prognosis of steroid-refractory AGVHD

• Many IS agents are active…but predispose to

infections+++

• Lack of uniform criteria of response to

various therapies

• Initial control of AGVHD is critical

• Intensified infection prophylaxis ++++(viral, bacterial and mycotic infections

are the most common causes of death

in patients with severe aGVHD)

• Nutritional support, replacementtherapy of enteral losses of fluids...

• Bone mineral retention and repair

• Pain control

Thank you… … ..for your attention… … ..for your patience… … ..for your cooperation within the SCT team… … ..for your

participation in clinical trialsaiming to improve GvHD diagnosis,prophylaxis and treatment