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Different types of medicines might be used to treat myelodysplastic syndromes (MDS).

Medicines to help treat low blood cell counts

An important part of treatment for many people with MDS are medicines to help raise blood cell counts. For more on these, see Supportive Therapy for Myelodysplastic Syndromes.

Chemotherapy

Chemotherapy (chemo) is the use of drugs to treat cancer. Some chemo drugs can be swallowed as pills, while others are injected by needle into a vein or under the skin. These drugs enter the bloodstream and reach most areas of the body. This type of treatment is useful for diseases such as MDS that are not only in one part of the body.

The goal of chemo is to kill the abnormal blood stem cells in the bone marrow and allow normal ones to grow back.

Chemo is typically given in cycles. Each cycle includes the period of treatment followed by a rest period to give you time to recover from the effects of the drugs. Cycles are most often 3 or 4 weeks long. The schedule varies depending on the drugs used.

Hypomethylating agents

These types of chemo drugs affect the way certain genes inside a cell are controlled. They activate some genes that help cells mature. They also kill cells that are dividing rapidly. Examples of this type of drug include:

• Azacitidine (Vidaza)
• Decitabine (Dacogen)

For some people with MDS, using one of these drugs can improve blood counts (sometimes enough so that blood transfusions aren’t needed), improve quality of life, lower the chance of the MDS progressing to acute myeloid leukemia (AML), and even help a person live longer.

Azacitidine is usually injected under the skin (subcutaneously).

Decitabine can be injected under the skin (subcutaneously) or into a vein (IV).

A newer form of this drug, known as Inqovi, combines decitabine with cedazuridine, which helps stop the decitabine from being broken down in the digestive system. This lets the patient take the drug by mouth as a tablet.

Side effects of hypomethylating agents

Hypomethylating agents can have some of the same side effects as standard chemo drugs (see below), but these are usually milder.

A major side effect of these drugs is usually an early drop in blood cell counts, which tends to get better as the drug begins to work. Other side effects can include:

• Fever
• Nausea/vomiting
• Diarrhea or constipation
• Fatigue and weakness

Standard chemo drugs for more intense treatment

Standard chemo drugs are not used often for people with lower-risk forms of MDS. But higher-risk MDS is more likely to progress to acute myeloid leukemia (AML), so some people with these types of MDS may get the same chemo treatment as people with AML.

The chemo drug most often used for MDS is cytarabine (ara-C). It can be given by itself at a low dose, which can often help control the disease, but doesn’t often put it into remission.

Another option is to give the same, intense type of chemo used for younger people with AML. This means giving cytarabine at a higher dose, along with other chemo drugs. This is used more often in younger, healthier patients with higher-risk forms of MDS. Some of the chemo drugs that can be combined with cytarabine are:

• Idarubicin
• Daunorubicin

Other chemo drugs might be used as well.

People with MDS who get higher-dose chemo are more likely to go into remission, but they also tend to have more severe, even life-threatening side effects, so this treatment is typically given in the hospital.

Side effects of chemo

Chemo drugs can cause many side effects. These depend on the type and dose of the drugs given and how long they are taken. Common side effects include:

• Hair loss
• Mouth sores
• Loss of appetite
• Nausea and vomiting
• Diarrhea or constipation

People with MDS often already have low blood counts, which can become even worse before they get better.

• Low white blood cell counts lead to an increased risk of serious infections.
• Low platelet counts (thrombocytopenia) can lead to problems with easy bruising and serious bleeding.
• Low red blood cell counts (anemia) can lead to fatigue and shortness of breath. In people with heart problems, severe anemia can lead to a heart attack.

If a person's blood cell counts get too low, they may need supportive therapy (including transfusions, growth factors, or other medicines) to help prevent or treat serious side effects. 

Most side effects from chemo will go away after treatment is finished. Your health care team can often suggest ways to lessen side effects. For example, drugs can be given to help prevent or reduce nausea and vomiting.

Chemo drugs can also affect other organs. For example:

• Idarubicin and daunorubicin can damage the heart, so they are often not given to people who already have heart problems.
• Cytarabine can affect the brain and cause balance problems, sleepiness, and confusion. This is more common with higher doses.

If serious side effects occur, the chemo treatments may have to be reduced or stopped, at least for a while. It's important to carefully monitor and adjust drug doses, because some side effects can be permanent.

Immune therapy

Some medicines can help treat MDS by affecting the body’s immune system.

Immunomodulating drugs (IMiDs)

Lenalidomide (Revlimid) belongs to a class of drugs known as immunomodulating drugs (IMiDs). It seems to work well in lower-risk MDS, often eliminating the need for blood transfusions, at least for a time.

This drug seems to work best when the MDS cells are missing a part of chromosome 5 . But it can also help some people with MDS who do not have this abnormal chromosome.

Side effects of lenalidomide can include:

• Low blood cell counts (most often the white blood cells and platelets)
• Diarrhea or constipation
• Fatigue and weakness

This drug can also increase the risk of serious blood clots in the legs (called deep vein thrombosis, or DVT) and lungs (called a pulmonary embolus, or PE). This drug might also cause serious birth defects if given to pregnant women. Because of this, it's only available through a special program run by the drug company.

Immune system suppression

Drugs that suppress the immune system can help some people with lower-risk MDS. These drugs are most helpful for people with low numbers of cells in the bone marrow (hypocellular bone marrow).

Anti-thymocyte globulin (ATG) is an antibody against a type of white blood cell called a T cell. For some people with MDS, T cells interfere with normal blood cell production, so giving ATG can be helpful.

ATG is given by infusion through a vein. It must be given in the hospital because it can sometimes cause severe allergic reactions leading to low blood pressure and problems breathing.

Cyclosporine is another drug that can suppress the immune system. It can be used along with ATG to help some people with MDS. Side effects of cyclosporine can include loss of appetite and kidney damage.

Targeted therapy drugs

IDH1 inhibitor

In some people with MDS, the cancer cells have a change (mutation) in the IDH1 gene, which normally helps cells make the IDH1 protein. Mutations in this gene can lead to an abnormal IDH1 protein, which can stop MDS cells from maturing the way they normally would.

Ivosidenib (Tibsovo) is an IDH1 inhibitor. It blocks the abnormal IDH1 protein, which helps the MDS cells mature into more normal cells. This drug can be used in people with advanced, previously treated MDS, if the MDS cells are found to have an IDH1 mutation. Your doctor can test your MDS cells for this mutation.This drug is taken once a day, by mouth.

Possible side effects of ivosidenib

Common side effects can include fatigue, nausea, vomiting, belly pain or swelling, diarrhea, loss of appetite, cough, low red blood cell counts (anemia), rash, and changes on lab tests showing the drug is affecting the liver.

Less common but more serious side effects can include changes in heart rhythm, pneumonia, and jaundice (yellowing of the eyes and skin).