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 a needle can be used to inject them 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 like chronic myelomonocytic leukemia (CMML) that are not only in one part of the body. Chemo cannot cure CMML, but it can help kill the abnormal bone marrow cells and allow normal ones to grow back.

Hydroxyurea

Hydroxyurea (hydroxycarbamate, Hydrea) is a chemo drug that has helped some patients with CMML live longer. This drug comes as a capsule that's taken by mouth daily. It can bring the numbers of white blood cells and monocytes down 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 need to have their blood counts checked regularly. Other side effects are usually mild and well tolerated. Some patients have stayed on this drug for years without problems.

Hypomethylating agents

These drugs affect the way some genes inside cells are controlled. They activate some genes that help cells mature. They also kill cells that are dividing rapidly. This helps the normal bone marrow cells grow again, often leading to improved blood counts and the need for fewer transfusions.

Examples of this type of drug include:

• Azacitidine (Vidaza
• Decitabine (Dacogen)

Azacitidine is given as a shot under the skin or into your blood (IV), often for 7 days in a row, once a month.

Decitabine is often injected into a vein (IV) over 3 hours every 8 hours for 3 days. This is repeated every 6 weeks. Decitabine can also be given by IV over an hour, each day for 5 days in a row, and repeated every 4 weeks.

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 allows the drug to be taken by mouth as a tablet, typically once a day for 5 days in a row, which is repeated every 4 weeks.

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

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

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 combos 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 can cause severe side effects, including life-threatening infections or other problems. Using lower doses of chemo drugs is an approach that can help lower the chance of serious side effects. This treatment is generally only used in young and otherwise healthy people with CMML. 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 people with advanced CMML.

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

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

Chemo often slows blood cell production. In CMML, this problem is usually made worse before it gets better. It can lead to:

• Less ability to fight 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 need 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 short-term and will go away over time after treatment ends. 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, testicles, ovaries, brain, heart, and lungs. With careful monitoring, such side effects are rare. If serious side effects do occur, the chemo treatments may have to be reduced or stopped, at least for a short time.

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