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Trade/other name(s): Gazyva

Why would this drug be used?

This drug is used to treat chronic lymphocytic leukemia (CLL). It is also being studied for use against other types of cancer.

How does this drug work?

Obinutuzumab is a type of targeted immunotherapy known as a monoclonal antibody. A monoclonal antibody is a man-made version of an immune system protein that fits like a lock and key with a certain protein.

Obinutuzumab is designed to seek out and lock onto the CD20 receptor, which is found on B lymphocytes (B cells) in the body. This receptor is on some normal B cells and also on B cells that are cancerous, as in chronic lymphocytic leukemia. By attaching to the cells, obinutuzumab tags the cells for destruction by the body’s immune system. It may also kill some cells directly.

Before taking this medicine

Tell your doctor…

  • If you are allergic to anything, including medicines, dyes, additives, or foods.
  • If you have ever tested positive for infection with the hepatitis B virus. This drug may cause reactivation of the infection in some people, which can be serious or even life threatening. Your doctor will want to monitor you carefully during treatment.
  • If you have any other type of infection. This drug should not be given to someone with an active infection.
  • If you have any type of heart disease. Some people have had life-threatening heart problems while taking this drug.
  • If you take any medicines for high blood pressure. This drug might lower your blood pressure, so your doctor might have you hold off on taking blood pressure medicines for the 12 hours before each treatment with this drug.
  • If you have any other medical conditions such as kidney disease, liver disease, congestive heart failure, diabetes, or gout. Your doctor may need to monitor you more closely during treatment.
  • If you are pregnant, trying to get pregnant, or if there is any chance of pregnancy. It is not known if this drug might cause problems if given during pregnancy (see “Precautions” below).
  • If you are breastfeeding. While no studies have been done, this drug might pass into breast milk and affect the baby.
  • If you think you might want to have children in the future. It is not known whether or not this drug can affect fertility. 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

This drug can lower your blood platelet count, which can increase your risk of uncontrolled bleeding (see “Precautions”). If your platelet count becomes low, you may need to avoid other drugs or supplements that interfere with blood clotting, because they might further raise the risk of bleeding. These include:

  • Non-steroidal anti-inflammatory drugs (NSAIDs) such as aspirin, ibuprofen (Advil, Motrin), naproxen (Aleve, Naprosyn) and many others
  • Warfarin (Coumadin), dabigatran (Pradaxa), rivaroxaban (Xarelto), apixaban (Eliquis), or other blood thinners, including any type of heparin injections
  • Anti-platelet drugs such as clopidogrel (Plavix) or prasugrel (Effient)
  • Vitamin E

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.

No other serious interactions with other drugs are known at this time, but this does not necessarily mean that none exist. Check with your doctor, nurse, or pharmacist about your other medicines, 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 some 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?

Obinutuzumab is given as an infusion into a vein (IV). It is usually given for a total of 6 cycles, with each cycle lasting 28 days.

Cycle 1: On the first day of treatment (Day 1), you’ll get a small dose of the drug (100 milligrams, or mg) slowly over 4 hours to see if you have any type of reaction to the infusion (see “Precautions” section). The next day (Day 2) you’ll get a larger dose (900 mg) over at least 3 hours. If you aren’t having any problems, you’ll get the next infusion 6 days later (on Day 8), and then another a week after that (on Day 15). Each of these 1,000 mg infusions are given over at least 2 hours.

Cycles 2 thru 6: For each of these cycles, treatment is given only on Day 1 of the cycle. You’ll get an infusion of 1,000 mg of the drug over at least 2 hours.

You will be given medicines before each infusion to help reduce the risk of reactions, including acetaminophen (eg, Tylenol). You’ll also get an antihistamine (by mouth or IV) such as diphenhydramine (eg, Benadryl) and a corticosteroid (IV) for at least the first 2 infusions. These medicines are given 30 minutes to 2 hours before the start of the obinutuzumab infusion. Tell your nurse right away if you begin to feel different at all during any of the infusions.

Starting the day before your first infusion, you might also get other medicines and plenty of fluids to help lower your risk of a serious side effect known as tumor lysis syndrome (see “Precautions”).


This drug can cause infusion reactions in some people while the drug is being given or within 24 hours, especially with the first 2 treatments. Mild reactions usually consist of fever and chills. More serious reactions are less common, but can be dangerous. Symptoms can include feeling lightheaded or dizzy (due to low blood pressure), fainting, headache, feeling warm or flushed, fever or chills, hives, itching, cough, shortness of breath, changes in heart rate, pain the back or abdomen, or swelling of the face, tongue, or throat. Tell your doctor or nurse right away if you notice any of these symptoms during or after being given the drug. Your doctor or nurse will give you medicine before the infusion to try to prevent a reaction.

This drug may cause reactivation of hepatitis B virus (HBV) infection in some people, which can be serious or even life threatening. Your doctor will test your blood for signs of HBV infection before starting treatment. Your doctor might also order blood tests during your treatment to look for possible signs of hepatitis. Tell your doctor or nurse right away if you notice possible symptoms of hepatitis, such as yellowing of the skin or eyes (jaundice).

In rare cases, use of this drug may lead to a serious brain infection known as progressive multifocal encephalopathy (PML). Tell your doctor or nurse right away if you notice any new symptoms such as trouble thinking, confusion, feeling dizzy, loss of balance, trouble talking or walking, weakness on one side of your body, or vision problems.

This drug might cause tumor lysis syndrome within a day of the first infusion in patients with large numbers of leukemia cells in their body before treatment. When the drug kills these cells, they break open and release their contents into the bloodstream. This can lead to kidney failure and might also affect the heart and nervous system. If your doctor thinks you are at risk for this, you will get medicines and lots of fluids before and during treatment to help the body get rid of these substances. Tell your doctor or nurse if you have nausea, vomiting, diarrhea, or tiredness after the first infusion.

Your doctor will test your blood throughout your treatment, looking for possible effects of the drug on blood cell counts (described below) or on other body organs. Based on the test results, you may be given medicines to help treat any effects. Your doctor may also need to reduce or delay your next dose of this drug, or even stop it altogether.

This drug can lower your white blood cell count. It might also have other effects on your immune system. 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, chills, pain when passing urine, new onset of cough, or bringing up sputum.

Do not get any immunizations (vaccines), either during or for some time after treatment with this drug, without your doctor’s OK. This drug may affect your immune system, which could make vaccines less effective, or could even lead to serious infections. Try to avoid contact with people who have recently received a live virus vaccine, such as the oral polio vaccine, smallpox vaccine, or nasal spray versions of the flu vaccine. Check with your doctor about this.

This drug may lower your platelet count in the weeks after it is given, which can increase your risk of bleeding. Speak with your doctor before taking any drugs or supplements that might affect your body’s ability to stop bleeding, such as aspirin or aspirin-containing medicines, warfarin (Coumadin), or vitamin E (see “Interactions with other drugs”). 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.

Women should avoid getting pregnant during and for at least 12 months after treatment with this drug in order to prevent harm to the fetus. Talk with your doctor about what kind of birth control you can use with this medicine. Tell your doctor right away if you become pregnant or think you may be pregnant.

Possible side effects

Most of the following side effects probably will not occur. Your doctor or nurse will want to discuss specific care instructions with you. They can help you understand these side effects and help you deal with them.


  • Infusion reaction, especially with first 2 infusions*
  • Lowered white blood cell count with increased risk of infection*

Less common

  • Lowered platelet count with increased risk of bleeding*
  • Lowered red blood cell count (anemia)
  • Fever
  • Cough
  • Muscle or bone pain


  • Reactivation of hepatitis B virus infection*
  • Brain infection (progressive multifocal leukoencephalopathy)*
  • Tumor lysis syndrome*
  • Death due to heart problems

*See the “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 2013

Disclaimer: This information may 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: 11/04/2013
Last Revised: 11/04/2013