Allogeneic stem cell transplantation with myeloablative conditioningMedical editor Lorentz Brinch MD
Oslo University Hospital
An allogeneic stem cell transplantation with myeloablative conditioning facilitates maximization of treatment with chemotherapy, perhaps in combination with total body radiation. The treatment involves removal of the patient's bone marrow and replacing it with new bone marrow from a donor with compatible tissue. Additionally, an immunological effect is often achieved directed toward the remaining leukemia cells. Hematopoetic stem cells are transferred from an individual who is normally tissue-identical but genetically different from the patient.
The patient should not have a serious, complicated disease and there must be an appropriate donor. Using a family donor, a transplantation with myeloablative conditioning is appropriate for patients under 60 years. Unrelated, HLA-identical donors are suitable for certain patients below 55-60 years. It is important to take into consideration the patient's biological age. If it is possible to choose between multiple donors, it is preferred that the donor is of the same sex as the patient. If possible, a CMV negative donor is preferred if the patient is CMV negative.
The treatment can cure otherwise incurable blood diseases, but its intensity is associated with many side effects. There is also a risk of fatal complications.
- Acute myeloid leukemia (AML)
- After recurrence, in the beginning of the first recurrence or in later, preferably second remission.
- In the first remission for patients who do not have a low risk for recurrence, if the patient is under 60 years and there is a family donor.
- Patients under 55-60 years with high risk for recurrence with unrelated suitable donor, in the first remission.
- Acute lymphoblastic leukemia (ALL)
- In the first remission with high risk criteria and for new remission after first recurrence.
- Chronic myeloid leukemia leukemia (CML)
- In the chronic phase with poor or no response of tyrosine kinase inhibitors or in accelerated phase.
- Multiple myeloma
- Younger patients with good response to primary treatment and with a suitable family donor. At the present time, the indication is debated.
- Serious aplastic anemia, myelodysplastic syndrome, primary myelofibrosis, chronic myelomonocyte leukemia, and other rare diseases.
A blood related donor is preferred and currently, a blood related donor with up to one incompatible HLA (human leukocyte antigen) can be used.
If the patient does not have a blood related donor, it is considered whether an unrelated donor with HLA, A, B, C, DR and DQ identity can be used. Despite serological techniques, unrelated donors may still have small differences in their HLA molecules which are of significance for GVHD and rejection reactions, therefore genomic typing is performed.
In younger patients, a stem cell transplantation for acute and chronic myeloid leukemia with marrow from an unrelated HLA genetically identical donor has given almost the same results as using stem cells from blood related donors.
The upper age limit for patients accepting stem cells from unrelated donors is somewhat lower than for patients who have a blood related donor because the risk for complications is greater and increases with age.
If it is not possible to find a living donor for the patient, searching for cord blood as a source of stem cells may be an altenative.
Stem cell harvesting
Hematopoietic stem cells are harvested by extracting bone marrow from the donor's hip bone or by mobilizing hematopoietic stem cells from bone marrow to blood. Mobilization can be done with the help of hematopoietic growth factors, most often granulocyte colony stimulating factor (G-CSF) given subcutaneously. The growth factors most likely influence adhesion molecules on the stem cells and bone marrow stroma allowing the stem cells to release into the blood stream. Because of this technique, it has become common to refer to stem cell transplantations instead of bone marrow transplantations as it reflects both methods of harvesting stem cells.
Harvesting from bone marrow
For extraction of stem cells from bone marrow, the tissue-compatible donor is given general anesthesia and lies in the prone position. Bone marrow is aspirated by repeated punctures of the hip bone. The procedure lasts 1 hour on average. The aspirated bone marrow with the stem cells is transferred to blood pouches with heparin. From the donor, 2 x 108 per/kg body weight of nuclei-containing cells are transferred to the recipient.
Harvesting from blood
Harvesting stem cells from blood does not require anesthesia, but the procedure can be time-consuming. The stem cells are harvested from a peripheral vein with the help of leukapheresis machines.
Each leukapheresis requires many hours. It is necessary to have 1-3 leukaphereses and a minimum of 2 x 106 CD34 of positive cells per/kg body weight of the recipient.
There are indications that the use of stem cells from blood can lead to quicker hematopoietic reconstitution than stem cells from bone marrow.
The application for a transplantation is submitted to the Allogeneic Stem Cell Group of Norway. As a minimum, the application must include a short disease history including information about the time of remission, treatment given, precise diagnosis and evidence for it. It is also necessary to provide cytogenetic and molecular genetic data. Information about complications from treatment, general health status, organ function, and whether the patient has a blood-related donor should also be included.
Examinations before transplantation
In addition to the different blood tests and bone marrow tests, there are a series of examinations which all patients must complete before a stem cell transpIantation:
- Lung function tests
- Dental examination
- Sperm examination/examination from gynecological clinic
- Eye examination
- X-ray examination of heart and lungs, possibly other organs
Sperm banking/ovarian tissue
It is important to offer sperm banking to men, if it is possible, before starting chemotherapy for a serious illness. It is realistic to assume the patient will be sterile after the transplantation.
Banking ovarian tissue is technically possible, but at current, use of this tissue is experimental.
The patient and their family should receive thorough information about treatment, complications, and circumstances which should be in order before the treatment.
The patient will also be offered to speak to another patient who has completed a stem cell transplantation.
Preparation for stem cell transplant
Before starting conditioning, there are measures which must be taken to prevent and treat complications of chemotherapy and GVHD.
All patients must have a central vein catheter. If it is necessary to perform plasma replacement due to ABO incompatibility, the patient will need a two-way dialysis catheter.
All blood products given during the time frame from one month before the transplantation to at least 12 hours after must be radiated to prevent proliferation of possibly included T-lymphocytes in the immunosuppressed patient, causing GVHD. Irradiation is necessary despite always using leukocyte-filtered blood products.
All patients should receive blood products which are filtered for leukocytes. This ensures that the products are functional with CMV-negative patients and are used on both anti CMV-positive and negative patients.
Three weeks before the transplantation, an antibiotic prophylaxis with trimetoprim-sulfa is started. This prophylaxis is taken until 4 days before the transplantation but is resumed with a stable graft. This treatment continues for 6 months from the transplantation day in patients without chronic GVHD, given the granulocyte count stays over 0.5 x 109/l. Patients requiring steroid treatment and/or who have chronic GVHD should continue with a pneumocystic pervecii prophylaxis for 6 months.
Valacyclovir is administered the day before the transplantation until 28 days after, if the patient is positive for herpes simplex and/or varicella zoster virus serology. The dosage is reduced if serum creatinine >150 mmol/l.
The mouth and throat are inspected daily for candida. For positive clinical findings, a nystatin mixture is given or amphotericin chewable tablets.
Cyclosporin and methotrexate are given routinely to prevent acute and chronic GVHD. Other regimens are also used.
Prevention of CNS recurrence
For acute lymphoblastic leukemia, 2 intrathecal methotrexate injections are administered as part of pre-treatment.
Bone marrow eradication treatment
For malignant blood diseases, a high-dose combination of busulfan and cylcophosphamide is given during the last 8 days before the transplant. Busulfan is given for 4 days and cyclophosphamide is given for 2 days. Patients who are not able to take busulfan orally will receive an intravenous preparation. In patients who have had CNS recurrence of acute leukemia, total CNS radiation may be appropriate before the other medications are given.
In special cases, it is recommended to administer fractioned total-body radiation and cyclophosphamide.
Prevention of hemorrhagic cystitis
Byproducts of chemotherapy drugs cause sores and inflammation of bladder mucosa causing bleeding. To prevent this, the following is administered:
- forced hydration – starting before the first dose of busulfan (or cyclophosphamide for total-body radiation) with continual intravenous infusion and measurement of diuresis. Hydration is stopped approximately 20 hours after the last infusion of cyclophosphamide
- mesna – uroprotector given intravenously for prevention of urinary toxicity in connection with administration of cyclophosphamide
Nausea prophylaxis and treatment
Metoclopramide is always given before busulfan and ondansetron is given before cyclophosphamide. Other medications are used in cases where this regimen is insufficient.
Infusion of stem cells
The stem cells are transferred to the recipient via intravenous infusion, as in a normal blood transfusion, or during support (as for HMAS) if the stem cells have been frozen .
The stem cells migrate to the recipient's bone marrow where they establish with the help of adhesion molecules and proliferate in a complicated, and far from fully clarified, interaction between cytokines, growth factors, and other cellular interactions.
After 2-4 weeks, the granulocytes will start to appear in the patient's peripheral blood. Effective platelet production usually starts somewhat later.
For ABO incompatibility between the donor and recipient, serious hemolysis may occur. Therefore, antibodies must be removed either by plasmapheresis, if the recipient has antibodies in a high titer against the donor erythrocytes, or by removing the plasma from the donor marrow if the donor has a high titer against the recipient. Sometimes erythrocytes must be removed from the stem cell product.
During the first weeks after a stem cell transplantation, the patient is very susceptible to infections, especially bacterial. The patient will remain in protected isolation with positive pressure ventilation and filtered air from the fifth day after the transplantation (granulocyte count < 0.2 x 10 9/l). The patient may come out of isolation when the granulocyte count is stable (> 0.2 x 109/l) for at least 3 consecutive days, sometimes longer.
During the period the patient is in isolation, the patient, family and health personnel must follow their respective routines to reduce the risk of infection. Certain routines are performed daily until the new marrow starts to function. The purpose of following these routines is to prevent complications and ensure that possible complications are discovered early.
- blood tests
- rectal temperature, pulse, and blood pressure
- weight measurement
- fluid balance
- inspection of mouth, throat, and skin
For complications, it is important that treatment is initiated as soon as possible.
Platelet and erythrocyte transfusions
Transfusions of thrombocytes and erythrocytes are necessary in the weeks after the transplantation to maintain platelets and Hb at safe levels.
During a stem cell transplantation with an ABO-incompatible donor, erythrocytes of type O are given subsequent to the transplantation until the erythrocytes in the patient have changed to the donor's blood type.
Chemotherapy generally causes nausea and vomiting. Medications can also influence sense of taste and reduce appetite for days or weeks. Most patients also experience mucositis with considerable pain after intensive chemotherapy.
The patient's nutritional status is monitored and the need for parenteral nutrition (TPN) is considered individually. Almost all patients need TPN for a period after conditioning and in the aplasia phase.
Mucositis, both in the mouth and other mucosa and intestines, often occurs when blood values are at their lowest. The intensity of the soreness is individual. Sore mucosa in the mouth is not only an entrance for bacteria, but can also be painful. Prophylactic oral hygiene should be performed during the entire treatment. Painful mucositis may necessitate treatment with analgesics, often opiates.
For painful rectal mucosa, ointment should be liberally applied. After each toilet visit, soft toilet paper dampened with peanut oil and subsequent abundant ointment should be used. A bath with green soap will soothe the pain.
Patients who have received intensive chemotherapy, and/or total body irradiation, usually experience diarrhea. This is due to temporary damage of the intestinal mucosa from the treatment. Diarrhea can be expected to last during, and a few weeks after the treatment.
GVHD can also cause intensive diarrhea. This type of diarrhea can occur a few weeks after the transplantation, about the time when the transplantation is expected to take, but also later on.
Intensive and broad spectrum antibiotic treatment in the aplasia phase will cause changes in the intestinal flora with diarrhea. Patients are also susceptible to infection from food.
Nutritional status is generally controlled by administering total parenteral nutrition with fluid, electrolyte, and protein substitution.
Some complications should be expected after the transplant. Complications are sometimes serious and life-threatening, and in the worst case, fatal.
Due to large doses of busulfan and cyclophosphamide, the patient will have a serious immune defect and granulocytopenia during the first few days after taking the medication.
For serious granulocytopenia, normal signs of infection will often not be present because the patient will not create pus. In the aplasia phase, bacterial infections are almost always primary, which can quickly become very serious. The only sign of infection is often fever, which must be taken very seriously for these types of patients.
A reliable microbiological diagnosis is obtained relatively rarely. In cases where there is bacterial growth, the treatment is adjusted according to the resistance pattern.
If the patient becomes afebrile from the antibiotic treatment, the treatment should continue for at least 3 days or until the granulocyte count is over 0.2 x 109/l.
Both GVHD prophylaxis and GVHD requiring treatment with steroids or another immunosuppressant, increase immune deficiency. Even after the patient has received sufficient granulocytes, the immune system is still impaired, with a significant risk for infections.
Important opportunistic microbes which can cause life-threatening infections are:
- cytomegalovirus (CMV)
- fungus (candida og aspergillus)
- pneumocystic jerovecii
- various bacteria
The patient must therefore be monitored by checking for the CMV antigen or PCR. Only leukocyte-filtered products can be used. These products rarely or never transfer CMV infections.
One should be aware of new lung infiltrates, especially in patients with chronic GVHD. It is important to try to obtain diagnostic material. The threshold for doing bronchoscopy with broncial rinsing is low.
In patients who are in the aplastic phase receiving antibiotics for 5-7 days without being afebrile, or who have a new rise in temperature despite adequate antibiotic treatment, a systemic or invasive fungal infection must be considered, especially if another infection cannot be detected in a blood culture. Empirical treatment must be considered with antimycotics in a sufficient dose, often intravenously must be considered.
Focal infiltrates are most often due to either a bacterial or fungal infection. It is important to be aware that patients without granulocytes rarely develop obvious infiltrates. An X-ray of the lungs is often negative in the aplasia phase. HR-CT is a much more sensitive examination. Infiltrates may become visible when the granulocytes return after the cytopenia phase, with a radiologically aggravation. This may be in spite of adequate treatment and clinical improvement. It is therefore very important with close clinical observation.
Interstitial pneumonia is a lung infection with numerous small areas of infection. The condition is a feared complication in stem cell transplanted patients. Interstitial pneumonia can occur both before and many months after the engraftment. The mortality is high. The condition may be due is due to infections sensitive to treatment.
- CMV infection
- Pneumocystic jerovecii (observed rarely during trimetoprim-sulfa prophylaxis)
It is therefore very important to initiate the correct treatment. Patients with interstitial pneumonia can quickly become dependent on a respirator and must be followed closely with a pulse oxymeter and by monitoration of arterial blood gases.
A CMV infection is not uncommon after an allogeneic stem cell transplantation and is often due to reactivation of a virus in sero-positive patients. Acute GVHD and treatment of this increases the risk.
The manifestations can vary from asymptomatic virus production via thrombocytopenia and leukopenia, to unexplained fever, hepatitis or gastrointestinal symptoms with life-threatening interstitial pneumonia.
CMV pneumonitis typically occurs 40-60 days after the transplantation but can also occur later on. The fear of CMV pneumonitis is one of the reasons leukocyte-filtered products are used for allogeneic stem cell transplantations.
Detection of a CMV infection (positive pp65 or CMV-PCR) will usually lead to starting treatment with ganciclovir. The dose is reduced for reduced renal function. For granulocytes under 0.7 x 109/l, foscarnet is given instead. pp65 or CMV-PCR should be monitored at least once a week during the treatment.
Hepatic veno-occlusive disease
This condition is due to chemotherapy and/or total body irradiation. An obstruction of sinusoidal blood flow is due to damaged terminal hepatic vessels and sublobular veins. The condition is rare and is often observed 3-4 weeks after the transplant.
The elevation of transaminase at the time of the transplantation causes an increased risk for hepatic veno-occlusive disease. The first sign is often gradual weight increase and increased need for platelet infusion. The patient may have intense abdominal pain, especially in the epigastrium and right hypochondrium, elevated bilirubin, and transaminase, with enlarged liver and soreness. Ascites may appear with weight gain, encephalopathy, and coagulopathy. At a later stage, the patient may develop hepatorenal syndrome.
The treatment is expectative and symptomatic. The patient must be followed clinically very closely with monitoration of fluid and electrolyte balance. The prognosis is poor for serious involvement.
These conditions occur rarely, but are potentially serious complications which affect about 5% of patients. The pathogenesis is only partly known, but endothelial damage is a central factor.
- Microangiopathic hemolytic anemia (MAHA)
- Hemolytic-uremic syndrome (HUS)
- Thrombotic thrombocytopenic purpura (TTP)
- serious hemolysis
- renal failure
- neurological manifestations due to reduced circulation in capillaries
The benefit of therapeutic measures is controversial. Cyclosporin A is replaced with mycopholate or tacrolimus. A problem is that tracrolimus can also cause thrombocytopenia. It is also possible, but seldom effective, to perform plasma exchange.
Graft-versus-host disease is a condition where T-lymphocytes from the donor attack cells and tissue of the patient.
Bone marrow failure
Bone marrow failure refers to lasting anemia, leukopenia, and thrombocytopenia. Causes for bone marrow failure may be:
- rejection of bone marrow
- delayed engraftment
- infection (CMV among others)
- bone marrow-toxic medications
Megakaryocyte function is restored often lastly restored after the stem cell transplantation. Thrombocytopenia may also be due to enhanced consumption of platelets from infection, GVHD, and immunizing.
In addition to reduced marrow function, anemia may be due to bleeding and/or hemolysis. For ABO incompatibility, a significant delay of adequate erythropoiesis is often observed (up to one year).
Anorexia may be due to infection, GVHD, renal dysfunction, or medications. If the patient in addition has problems with swallowing, esophagitis, gastritis, or an ulcer may be the cause. The nutritional status should be maintained intravenously, as needed, which itself may cause anorexia in some patients.
Hemorrhagic cystitis is primarily due to high doses of cyclophosphamide, however, high doses of busulfan also play a role. Despite prophylactic measures with forced hydration and mesna, some patients still develop hematuria/dysuria/pollakisuria. The symptoms generally appear during or in the first three days after a cyclophosphamide infusion. Some patients can also develop hemorrhagic cystitis later on, possibly as a manifestation of GVHD, but also from a viral infection (CMV, adenovirus, BK virus).
The treatment is to continue or resume forced hydration/diuresis. Analgesics or antiviral treatment is started if necessary.
Recurrence after allogeneic stem cell transplantation
For recurrence after a transplantation for CML, it has been shown that an infusion of T-lymphocytes from the donor causes complete remission in about 70% of patients who recur to a chronic phase. This GVL (graft-versus-leukemia) effect is more poorly documented in recurrence after transplantation for acute leukemia.