Chemotherapy for Chronic Myelomonocytic Leukemia

Chemotherapy (chemo) is the use of drugs for treating a disease such as cancer. The drugs can be swallowed as pills, or they can be injected by needle into a vein or muscle. Chemo is considered systemic treatment because these drugs enter the bloodstream and reach most areas of the body. This type of treatment is useful for diseases such as chronic myelomonocytic leukemia (CMML) that are not localized to one part of the body. The purpose of the chemo is to eliminate the abnormal bone marrow cells and allow normal ones to grow back.


Hydroxyurea (hydroxycarbamate, Hydrea®) is a chemo drug that has helped some patients with CMML live longer. This drug comes as a capsule and is taken by mouth daily. It can lower the counts of white blood cells and monocytes to normal. It may also help shrink an enlarged spleen. Because the main effect of hydroxyurea is to lower blood counts, anyone taking this drug will have their blood counts checked regularly. Other side effects are usually mild and easily tolerated. Some patients have stayed on this drug for years without ill effects.

Hypomethylating agents

These drugs are actually a form of chemo that affects the way genes are controlled. Examples of this type of drug include azacytidine (Vidaza®) and decitabine (Dacogen®). These drugs have been studied best in the treatment of myelodysplastic syndromes, where they seem to help stop abnormal cells in the bone marrow from dividing to make new cells. This lets the normal cells grow again, often leading to improved blood counts and less need for transfusions. Fewer patients with CMML were treated with these drugs in studies, but they had similar benefits in terms of blood counts.

Side effects are usually mild and rarely lead to stopping treatment, but these drugs can have some of the same side effects as regular chemotherapy, including:

  • Nausea/vomiting
  • Diarrhea
  • Fatigue and weakness
  • Low blood counts (most often the white blood cells or platelets)

Conventional chemotherapy

For a long time, CMML was grouped with myelodysplastic syndromes, and so it was treated with the same chemo drugs. Some of the chemo regimens that have been used include:

  • Cytarabine (ara-C) with idarubicin,
  • Cytarabine with topotecan
  • Cytarabine with fludarabine

Sometimes, topotecan is given by itself.

This type of treatment can help some patients, but it is very toxic. Side effects can be severe and may even hasten death. This treatment is generally only used in young and otherwise healthy CMML patients. Most patients with CMML are older and have other health problems. They are less likely to benefit from this intense type of chemo. Still, this may be an option for some patients with advanced CMML.

Another option is to use lower doses of chemo drugs. This approach can lower the chance of serious side effects.

Chemo drugs can cause many side effects. The side effects depend on the type and dose of the drugs that are given and the length of time they are taken. Common side effects include:

  • Hair loss
  • Mouth sores
  • Loss of appetite
  • Nausea and vomiting
  • Low blood counts

Chemotherapy often slows blood production, leading to low blood counts. In CMML, this problem is usually made worse before it gets better. It can lead to:

  • Lowered resistance to infection (due to low white blood cell counts)
  • Easy bruising and bleeding (due to low platelet counts)
  • Fatigue (due to low red blood cell counts).

When platelet counts get very low, patients may receive platelet transfusions to prevent or stop bleeding. Likewise, fatigue caused by low red blood cell counts can be treated with red blood cell transfusions.

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

Chemo drugs can also damage organs such as the kidneys, liver, testes, ovaries, brain, heart, and lungs. With careful monitoring, such side effects are rare. If serious side effects occur, the chemo treatments may have to be reduced or stopped, at least temporarily.

Carefully monitoring and adjusting drug doses are important because some of these side effects can be permanent.

See the Chemotherapy section of our website for more information about chemo and its side effects.

The American Cancer Society medical and editorial content team
Our team is made up of doctors and master’s-prepared nurses with deep knowledge of cancer care as well as journalists, editors, and translators with extensive experience in medical writing.

Last Medical Review: January 19, 2014 Last Revised: February 17, 2016

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