Allogeneic Stem Cell Transplant Risks

What are the risks of an allogeneic stem cell transplant?

The most serious risks of allogeneic stem cell transplants are:

  1. . Graft-versus-host disease (GvHD)
  2. . Risk of infection
  3. . Side effects of high-dose anti-cancer treatment
  4. . Graft failure
  5. . Late effects

Read more about : Bone Marrow Transplant Side Effects and Risks

Graft-versus-host disease

Graft-versus-host disease (GvHD) is a common complication of an allogeneic stem cell transplant. It happens when the new immune system that grows from the donor cells (the ‘graft’) recognizes the other cells in your body (the ‘host’) as foreign, and attacks them.

This effect is useful when it attacks your lymphoma cells, but it can also attack healthy tissues. This can cause serious side effects. Most of the time, GvHD causes mild-to-moderate symptoms, but occasionally, it can be severe and even life-threatening. Before and after your transplant, you are given treatment to reduce your risk of developing GvHD. Your transplant team monitors you closely for any signs of GvHD so they can treat it as early as possible if it develops.

GvHD is classed as ‘acute’ or ‘chronic’ depending on when you experience it and the signs and symptoms you have.

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. Acute GvHD

Acute GvHD classically develops within 100 days of your transplant – although it might develop later, particularly if you’ve had reduced-intensity conditioning therapy. Up to half of all people who have an allogeneic stem cell transplant develop some degree of acute GvHD. It mainly affects the skin, the gut and the liver. It can cause:

. A sore, itchy rash, often on the hands, feet, ears and chest, although it can spread to the whole body.

. Feeling sick (nausea), being sick (vomiting), tummy pain and weight loss

. Diarrhea, which can be watery or bloody

. Fever

. Jaundice (a build-up of a chemical called ‘bilirubin’, which can make the whites of your eyes and your skin look yellow).

Acute GvHD is graded from 0 (mild) to 4 (very severe) based on the symptoms you have. Grading helps your doctor to decide what treatment to give you.

Although acute GvHD is unpleasant, and can sometimes be severe, it is also a sign that your new immune system is attacking any lymphoma cells left in your body after high-dose treatment.

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. Chronic GvHD

Chronic GvHD generally develops more than 100 days after your transplant. It is most likely to develop in the first year after your transplant, but it can happen later. It affects around half of all people who experienced acute GvHD but it can develop even if you didn’t have acute GvHD.

Chronic GvHD most often affects the mouth, skin, gut and liver. It can also affect other areas, such as your eyes, joints, lungs and genitals. The features of chronic GvHD are different from those of acute.

Symptoms of GvHD can include:

. Skin rashes, flaking or itchy skin, changes in skin tone or texture, tightening of the skin.

. Dry or irritated eyes

. Dry or sore mouth

. Thinning of your hair

. Indigestion, diarrhoea, nausea, vomiting or unexplained weight loss.

Your doctor should assess you for GvHD regularly as part of your follow-up. For each part of your body affected by chronic GvHD, they might give you a score between 0 (no impact) and 3 (severe impact) based on the impact your symptoms have on your daily life. This helps them decide on the best treatment for you.

If you have any signs of GvHD, you will have tests to find out what areas of your body are affected and how severe it is. These might include blood tests, X-rays and scans.

. Prevention and treatment of GvHD

Before and after your transplant, you have drugs to dampen your immune system (immunosuppressant drugs) to try to prevent GvHD developing or to limit the effects of it if it does develop. They are often started during your conditioning therapy.

The most common drugs used to prevent GvHD are:

. Methotrexate, a type of chemotherapy given through a drip into a vein. You usually have it on days 1, 3, 6 and 11 after your stem cell infusion.

. Ciclosporin, an immunosuppressant medicine. You have it through a drip into a vein every day at first and then as oral tablets once your blood counts have recovered. You carry on taking it when you go home after your transplant. The dose is gradually reduced as your new immune system becomes less reactive to your own body tissues. This might take several years.

Some transplant centres use different drugs, particularly for people who have reduced-intensity conditioning or who only have a partially matched stem cell donor. Newer treatments are also being studied to see if they are more effective at preventing GvHD than current treatments.

If you develop GvHD, your doctor might increase your immunosuppressant drugs. If this is not effective, you might need high doses of steroids to suppress your immune system further. You also have treatments to help control your symptoms of GvHD. These vary depending on the parts of your body that are affected.

If steroids do not control GvHD, there are a range of other treatment options. Your doctor chooses your treatment based on your individual circumstances.

Because treatment for GvHD suppresses your immune system, it can increase your risk of developing infections. Your transplant team tries to find the right balance of medications that allows your immune system to fight infections without attacking healthy cells.

As time goes on, your new immune system usually becomes more tolerant to your host cells and you can gradually come off your immunosuppressant drugs. Sometimes GvHD can develop or flare up when your immunosuppressant drugs are reduced, so your medical team monitor you closely. If GvHD develops or comes back, you restart the immunosuppressant drugs.

Risk of infection

After an allogeneic stem cell transplant, you have very low blood counts for a few weeks. Having a low white blood cell count, especially a type of blood cell called ‘neutrophils’ (neutropenia) puts you at very high risk of developing an infection. These infections can be serious but they can be treated, particularly if they are caught early. They can lead to a long stay in hospital.

While you are in hospital after having your transplant, your medical team take precautions to reduce your risk of infection. They also monitor you closely for any signs of infection. Although taking precautions can reduce your risk of infection, you cannot avoid all sources of infection. Most people develop infections after an allogeneic stem cell transplant.

In the first month or so after an allogeneic stem cell transplant, you are at highest risk of developing bacterial infections, such as bloodstream infections, pneumonia, digestive system infections or skin infections.

In the next few months, you are most at risk of developing viral infections. These might be viruses that were lying dormant in your body before your transplant that may flare up when your immune system is low. They don’t always cause symptoms. You have regular blood tests after your transplant to make sure you don’t have a flare-up of a viral infection called cytomegalovirus (CMV). If your blood tests show CMV is present – even if you have no symptoms – you have treatment with antiviral drugs. You might need more than one course of treatment.

Your blood counts start to rise between 2 to 4 weeks after an allogeneic stem cell transplant. However, it can take many months, or sometimes even years, for your immune system to recover fully, especially if you are still taking immunosuppressant drugs to prevent GvHD.

When you go home, your team should tell you what signs of infection to look out for and who to contact if you are worried you might have an infection.

Contact your medical team immediately if you have any signs of infection.

Read more about : Bone Marrow Transplant Recovery

Side effects of conditioning treatment

You are likely to experience side effects from your high-dose anti-cancer treatment. We have separate information on the most common side effects of lymphoma treatments, including practical tips on how to cope with them. You might find the following pages particularly helpful:

. Oral mucositis (sore mouth)

. Anaemia (low red blood cell count)

. Thrombocytopenia (low platelet level)

. Nausea and vomiting

. Bowel problems.

Graft failure

Graft failure occurs if the transplanted stem cells fail to settle in your bone marrow and make new blood cells. This means your blood counts do not recover, or they begin to recover but then go down again. Graft failure is serious but it is rare after an allogeneic stem cell transplant, especially if your donor is a good match. Your medical team monitors your blood counts closely. If your graft does start to fail, you might be treated initially with growth factors or hormones. These can encourage the stem cells in your bone marrow to produce more cells. You might need a second stem cell transplant, either from the same stem cell donor or a different one.

Late effects

Late effects are health problems that may develop months or years after your lymphoma treatment. Most transplant centres have dedicated late effects services that offer screening programmes to detect late effects as early as possible. This gives you the best chance of being treated successfully if you develop any late effects.

Your transplant team should tell you what late effects you are at risk of and what you can do to reduce your risk of developing them. For more information, see our page on late effects of lymphoma treatment.

You may also be at risk of developing post-transplant lymphoproliferative disorder (PTLD) – lymphomas that can develop in people who are taking immunosuppressant drugs after a transplant. However, PTLD is rare. Most people who have had transplants do not develop PTLD. Your transplant team will talk to you about your individual risk and any signs or symptoms you should look out for.

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