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Obinutuzumab (Gazyva™)

The Abramson Cancer Center of the University of Pennsylvania
Last Modified: February 5, 2014

Pronounced: OH-bin-yoo-TOO-zoo-mab
Classification: Monoclonal Antibody

About Obinutuzumab

Obinutuzumab is a synthetic (man made) antibody directed against a protein called CD20, found on the surface of normal and cancerous B-cells, which are part of the immune system. More than 90% of CLL cases affect the B cells, making this a good target for therapy. An antibody is a part of the immune system that "marks" things (such as germs, bacteria and, in this case, cancer cells) to be destroyed by the immune system. Once this medication attaches itself to the B cells expressing CD20, it summons the body's immune system to attack and destroy those cells.

How to Take Obinutuzumab

Obinutuzumab is given by intravenous (into a vein) infusion. It may take several hours or longer to receive your first dose of obinutuzumab. Depending on how you tolerate the medication, you may receive subsequent doses more quickly.

You should not receive this medication if you have an active infection or have recently received a vaccine containing a live virus while on therapy (including oral polio, smallpox, MMR, nasal flu, and chickenpox vaccines).

Possible Side Effects of Obinutuzumab

There are a number of things you can do to manage the side effects of Obinutuzumab. Talk to your doctor or nurse about these recommendations. They can help you decide what will work best for you. These are some of the most common side effects:

Infusion and Allergic Reactions

Allergic or infusion reactions may occur during the first few treatments, and up to 24 hours after the infusion. You will be given diphenhydramine (Benadryl®), acetaminophen (Tylenol®) and an IV steroid before your treatment to reduce the chance of a reaction. During the infusion, if you experience difficulty breathing or swallowing, experience chest pain, “racing” heart, cough or wheezing, develop flushing or hives, lightheadedness, fever, chills, or shakes, inform your nurse immediately. Additional medications may be given to alleviate your discomfort. Your infusion may be slowed or temporarily stopped.

Low White Blood Cell Count (Leukopenia or Neutropenia)

White blood cells (WBC) are important for fighting infection. While receiving treatment, your WBC count can drop, putting you at a higher risk of getting an infection. You should let your doctor or nurse know right away if you have a fever (temperature greater than 100.4°), sore throat or cold, shortness of breath, cough, burning with urination, or a sore that doesn't heal.

Tips to preventing infection:

  • Washing hands, both yours and your visitors, is the best way to prevent the spread of infection.
  • Avoid large crowds and people who are sick (i.e.: those who have a cold, fever or cough or live with someone with these symptoms).
  • When working in your yard, wear protective clothing including long pants and gloves.
  • Do not handle pet waste.
  • Keep all cuts or scratches clean.
  • Shower or bath daily and perform frequent mouth care.
  • Do not cut cuticles or ingrown nails. You may wear nail polish, but not fake nails.
  • Ask your doctor or nurse before scheduling dental appointments or procedures.
  • Ask your doctor or nurse before you, or someone you live with, has any vaccinations.

For more suggestions, read the Neutropenia Tip Sheet.

Low Platelet Count (Thrombocytopenia)

Platelets help your blood clot, so when the count is low you are at a higher risk of bleeding. Let your doctor or nurse know if you have any bleeding or excess bruising, including nose bleeds, bleeding gums or blood in your urine or stool. If the platelet count becomes too low, you may receive a transfusion of platelets.

  • Do not use a razor (an electric razor is fine).
  • Avoid contact sports and activities that can result in injury or bleeding.
  • Do not take aspirin (salicylic acid), non-steroidal, anti-inflammatory medications (NSAIDs) such as Motrin®, Aleve®, Advil®, etc. as these can all increase the risk of bleeding. Unless your healthcare team tells you otherwise, you may take acetaminophen (Tylenol).
  • Do not floss or use toothpicks and use a soft-bristle toothbrush to brush your teeth.

Read the thrombocytopenia tip sheet for more information.

Reproductive Concerns

Exposure of an unborn child to this medication could cause birth defects, so you should not become pregnant or father a child while on this medication. Even if your menstrual cycle stops or you believe your sperm is affected, effective birth control is necessary during treatment and up to 12 months after stopping treatment.

Other Side Effects

Rare, but serious side effects include:

  • If your white blood cell (lymphocyte) count is very high prior to treatment, you are at risk for tumor lysis syndrome. This happens when the leukemia cells die too quickly and their waste overwhelms the body. You may be given a medication (allopurinol) and IV fluids to help prevent this. If you experience nausea, vomiting, diarrhea or become lethargic (drowsy, sluggish), notify your oncology team right away.
  • Progressive Multifocal Leukoencephalopathy (PML) is a rare, serious brain infection caused by a virus. Report any of the following to your healthcare provider right away: confusion, loss of balance, difficulty walking or talking, weakness on one side of your body or any vision changes.
  • Reactivation of hepatitis B infection in people who have been previously exposed to the virus. Before starting therapy, your healthcare provider will test your blood to see if you have been previously exposed. If you develop any worsening fatigue or yellowing of the skin or eyes, notify your oncology team.


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