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Trade/other name(s): Clolar

Why would this drug be used?

Clofarabine is used to treat acute lymphoblastic leukemia (ALL). It’s used in children and young adults up to 21 years of age. It may also be used for other types of cancer.

How does this drug work?

Clofarabine belongs to the general group of chemotherapy drugs known as anti-metabolites. It prevents cells from making DNA and RNA, which stops the growth of cancer cells.

Before taking this medicine

Tell your doctor…

  • If you are allergic to anything, including medicines, dyes, additives, or foods.
  • If you have any medical conditions such as kidney disease, liver disease (including hepatitis), heart disease, congestive heart failure, diabetes, gout, or infections. These conditions may require that your medicine dose, regimen, or timing be changed.
  • If you are pregnant, trying to get pregnant, or if there is any chance of pregnancy. See “Precautions”. Check with your doctor about what kinds of birth control can be used with this medicine.
  • If you are breast-feeding. It is not known whether this drug passes into breast milk. If it does, it could harm the baby.
  • If you think you might want to have children in the future. Some drugs can cause sterility. Talk with your doctor about the possible risk with this drug and the options that may preserve your ability to have children.
  • About any other prescription or over-the-counter medicines you are taking, including vitamins and herbs. In fact, keeping a written list of each of these medicines (including the doses of each and when you take them) with you in case of emergency may help prevent complications if you get sick.

Interactions with other drugs

Any drugs or supplements that interfere with blood clotting can raise the risk of bleeding during treatment with clofarabine. These include:

  • Vitamin E
  • Non-steroidal anti-inflammatory drugs (NSAIDs) such as aspirin, ibuprofen (Advil, Motrin), naproxen (Aleve, Naprosyn), and many others
  • Warfarin (Coumadin)
  • Ticlopidine (Ticlid)
  • Clopidogrel (Plavix)
  • Dabigatran (Pradaxa)
  • Rivaroxaban (Xarelto)
  • Apixaban (Eliquis)
  • Any type of heparin injections, such as enoxaparin (Lovenox), dalteparin (Fragmin), and tinzaparin (Innohep)

Note that many cold, flu, fever, and headache remedies contain aspirin or ibuprofen. Ask your pharmacist if you aren't sure what's in the medicines you take.

If you take medicines that affect blood pressure, your doctor will need to watch your heart and blood pressure more closely during treatment.

Your doctor may tell you to hold off taking any medicines or supplements that affect the kidneys or the liver during the days that you take clofarabine.

Check with your doctor, nurse, or pharmacist about other medicines, vitamins, herbs, and supplements, and whether alcohol can cause problems with this medicine.

Interactions with foods

No serious interactions with food are known at this time. Check with your doctor, nurse, or pharmacist about whether foods may be a problem.

Tell all the doctors, dentists, nurses, and pharmacists you visit that you are taking this drug.

How is this drug taken or given?

Clofarabine is given in a vein (I.V.) over 2 hours daily for 5 days in a row. This treatment is repeated every 2 to 6 weeks, based on how well you are doing. The dose depends on your height and weight, blood counts, and kidney and liver function.

Fluids and other medicines such as allopurinol and steroids may also be given during treatment to prevent complications. You may also be given a medicine to prevent nausea and vomiting before you take this drug.


Do not get any immunizations (vaccines), either during or after treatment with this drug, without your doctor's OK. Clofarabine may affect your immune system. This could make vaccinations ineffective, or could even lead to serious infections if you get live virus vaccines during or soon after treatment. Try to avoid contact with people who have recently received a live virus vaccine, such as the oral polio vaccine or smallpox vaccine. Check with your doctor about this.

Clofarabine can lower your blood counts (white blood cells, red blood cells, platelets), and may affect other organs. Your doctor will check your blood counts before and after each treatment to see how it affected your blood counts. Liver and kidney function are also checked often during treatment. Keep all your appointments for lab tests and doctor visits.

This drug can lower your white blood cell count, especially in the weeks after the drug is given. This can increase your chance of getting an infection. Be sure to let your doctor or nurse know right away if you have any signs of infection, such as fever (100.5° or higher), chills, pain when passing urine, a new cough, or bringing up sputum.

Clofarabine may lower your platelet count in the weeks after it is given, which can increase your risk of bleeding. Rarely, serious bleeding in the intestine, brain, or lungs can occur, which can be life-threatening. Speak with your doctor before taking any drugs or supplements that might affect your body's ability to stop bleeding, such as aspirin or medicines containing aspirin warfarin (Coumadin), or vitamin E. Tell your doctor right away if you have unusual bruising, or bleeding such as nosebleeds, bleeding gums when you brush your teeth, or black, tarry stools.

This drug may lower your red blood cell count. If this occurs, it is usually a few months after starting treatment. A low red blood cell count (known as anemia) can cause shortness of breath, or make you to feel weak or tired all the time. Your doctor may give you medicines to help prevent or treat this condition, or you may need to get blood transfusions.

This drug can cause the rapid killing of tumor cells, which in some cases has led to serious kidney damage within the first 24 hours of treatment (a condition known as tumor lysis syndrome). This is more likely if you have a very large number of cancer cells in the body. If your doctor feels you might be at risk, he or she will give you medicines and/or fluids to help prevent this. If you notice pain in your back or side, or see blood in your urine, let your doctor know right away.

Clofarabine can cause a condition known as hand-foot syndrome, in which a person may have pain, numbness, tingling, reddening, or swelling in the hands or feet. Peeling, blistering, or sores on the skin in these areas are also possible. Let your doctor know right away if you notice any of these symptoms.

A more serious skin reaction can happen rarely, starting with fever, sore throat, and trouble swallowing, along with redness and soreness of the eyes, mouth, throat, and other mucous membranes. On the skin it can start as a painful red rash or purple spots and evolve into blisters. This is called Stevens Johnson syndrome or toxic epidermal necrolysis. It can become life-threatening and must be treated quickly.

This drug has caused severe liver damage in a few people. Your doctor will likely check your blood so that if this happens, it can be found early. Call your doctor right away if you notice nausea, vomiting, fatigue, poor appetite, dark urine, yellowing skin or eyes, or tenderness under the right side of the rib cage.

In some people, the colon or intestine can become inflamed with serious complications such as holes, bleeding, loss of circulation to the intestine, or leakage from the intestine leading to serious infection. Tell your doctor if you have pain in your belly (abdomen), especially if you also have nausea or vomiting.

Rarely, clofarabine may cause fluid to leak out of blood vessels and build up in your lungs, called systemic inflammatory response syndrome (SIRS) or capillary leak syndrome. Your doctor and nurses will be watching you closely for this. Let your doctor know right away if you feel short of breath, dizzy, lightheaded, or faint. Also, let the doctor know if you have a fast heartbeat, less urine, or if you are unable to keep down fluids and food.

While taking this medicine, and for a few days after, there is a slight chance of a serious skin reaction. It can start as a rash with redness or blistering in the mouth, nose, or eyes, along with fever and body aches. If this happens, call your doctor right away.

Women should avoid pregnancy while taking this drug and for some time after. Clofarabine can harm the fetus and cause birth defects if taken during pregnancy. If there is any chance you might get pregnant, talk with your doctor about effective birth control.

Possible side effects

You will probably not have most of the following side effects, but if you have any talk to your doctor or nurse. They can help you understand the side effects and cope with them.


  • Low white blood cell count with increased risk of infection, fever*
  • Low platelet count with increased risk of bleeding*
  • Low red blood cell count (anemia) with symptoms like fatigue, fast breathing, pale skin and gums*
  • Nausea
  • Vomiting
  • Diarrhea
  • Infections

Less common

  • Sores in mouth or on lips
  • Fast heart beat
  • Swelling
  • Poor appetite
  • Hair loss
  • Fever
  • Aches and pains in belly, arms or legs
  • Shaking or body stiffness (rigors)
  • Dizziness
  • Tiredness (fatigue)
  • Headache
  • Feeling anxious or irritable
  • Blood in the urine*
  • Rash, itching of skin*
  • Flushing
  • Low or high blood pressure
  • Changes in the heart's ability to pump
  • Changes in the liver's function
  • Numbness or tingling of palms or soles of feet, with rash and peeling of skin*


  • Fluid backup in the lungs (capillary leak syndrome or SIRS), with trouble breathing, fast heartbeat, dizziness, or faintness
  • Bleeding in the brain (stroke), intestine, or lungs*
  • Liver failure
  • Death due to infection, lung problems, organ failure, bleeding, or other causes

*See “Precautions” section for more detailed information.

There are other side effects not listed above that can also occur in some patients. Tell your doctor or nurse if you develop these or any other problems.

FDA approval

Yes – first approved in 2004

Disclaimer: This information does not cover all possible uses, actions, precautions, side effects, or interactions. It is not intended as medical advice, and should not be relied upon as a substitute for talking with your doctor, who is familiar with your medical needs.

Last Medical Review: 12/02/2014
Last Revised: 12/02/2014