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Antibody — Antibodies are proteins the body makes to fight back when it notices substances or small particles that shouldn't be there. These may be things that are trying to attack the body (like bacteria, viruses or fungi) or chemicals.

Antibody therapy — Antibody therapy is when antibodies are used as a treatment for diseases such as cancer.

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B cell — B cells are a type of white blood cells that form part of the body's natural defense system. Their role in this system is to make antibodies. B cells are sometimes also called B lymphocytes.

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Chemotherapy — A type of drug used for the treatment of cancer.

CLL — see Chronic Lymphocytic Leukemia

Chronic Lymphocytic Leukemia — Also called CLL. A type of cancer where the body contains too many "immature" white blood cells (white blood cells are part of the body's natural defense system). These immature white blood cells mostly collect in the blood and bone marrow.

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Diarrhea — frequent and watery bowel movements.

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Fatigue — Feeling extreme tiredness, and not able to do everyday things due to lack of energy.

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LFT — see Liver Function Test

Liver Function Test — Also called LFT. A blood test that helps show how well your liver is working and can identify possible reactions to medications on liver function.

Lymphocytes — A specific type of white blood cell. They play an important part in the body's natural defense system (the 'immune system'). There are two main types of lymphocytes — B lymphocytes (B cells) and T lymphocytes (T cells). Each has a different role in helping to protect the body against things that should not be there.

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Molecule — A single 'unit' of a particular substance. Each unit is built in the exact same way, with the same number of 'building blocks' arranged in the same pattern.

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Neutropenia — A decrease below normal in the concentration of neutrophils, a type of white blood cell.

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PI3-Kinase, or PI3K — Short for phosphatidylinositol 3-kinase. A protein found inside a B cell. It is one of the molecules that play a part in the growth of cancerous B cells and normal B cells. It is the growth of these cells that leads to the development of Chronic Lymphocytic Leukemia (CLL).

PI3-Kinase (PI3K) inhibitor — A chemical substance that slows down, interferes with or reduces the action of PI3-Kinase, or 'PI3K'. ZYDELIG is a PI3-Kinase inhibitor.

Placebo — A treatment that does not contain any active ingredients, but looks the same, and is taken in the same way as a real medicine or treatment.

Primary Endpoint — A primary endpoint is the main goal or purpose of a drug study, to test whether or not a treatment does what it is intended to do.

Progression — In terms of cancer, progression means either the spreading of cancer to other areas of the body or when the cancer becomes worse.

Progression-Free Survival (PFS) — In clinical trials, progression-free survival is the duration of time that patients remain alive without their disease becoming any worse.

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Rai Staging System — A ranking system used to categorize the different stages of disease in Chronic Lymphocytic Leukemia (CLL).

Relapse — The return of the signs and symptoms of a patient's disease following a period of improvement.

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Side effect — A health problem that occurs when a treatment a patient is taking to help fight their disease also has an unwanted effect on their body.

Stages — The different 'stages' of cancer are a way to describe how far the cancer has spread in the body.

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Safety Profile

Information about managing certain side effects associated with ZYDELIG.

Learn About Possible Side Effects

Important Safety Information

What is the most important information I should know about ZYDELIG?

ZYDELIG can cause serious side effects that can lead to death, including:

  • Liver problems. Abnormal liver blood test results are common during treatment with ZYDELIG. ZYDELIG can cause severe liver problems. Your doctor will do blood tests before and during your treatment with ZYDELIG to check for liver problems. Tell your doctor right away if you get yellowing of your skin or the white part of your eyes (jaundice), dark or brown (tea-colored) urine, pain in the upper right side of your stomach area (abdomen), or bleeding or bruising more easily than normal.
  • Severe diarrhea. Diarrhea is common during treatment with ZYDELIG and can sometimes be severe. Tell your doctor right away if the number of bowel movements you have in a day increases by 6 or more. Ask your doctor about medicines you can take to treat your diarrhea.
  • Lung or breathing problems. Your doctor may do tests to check your lungs if you have breathing problems during treatment with ZYDELIG. Tell your doctor right away if you get new or worsening cough, shortness of breath, difficulty breathing, or wheezing.
  • Infections. Tell your doctor right away if you have a fever or any signs of an infection while taking ZYDELIG.
  • Tear in intestinal wall (perforation). Tell your doctor or get medical help right away if you get new or worsening stomach area (abdomen) pain, chills, fever, nausea, or vomiting.
  • Severe skin reactions. Tell your doctor right away if you get painful sores or ulcers on your skin, lips, or in your mouth; a severe rash with blisters or peeling skin, or a rash with itching.

If you have any of the above serious side effects during treatment with ZYDELIG, your doctor may completely stop your treatment, stop your treatment for a period of time, or change your dose of ZYDELIG.

Who should not take ZYDELIG?

  • Those with a history of serious allergic or skin reactions, as determined by a doctor.

What are the other possible side effects of ZYDELIG?

ZYDELIG can cause serious side effects, including:

  • Serious allergic reaction. Tell your doctor or get medical help right away
  • Low white blood cell count (neutropenia). Neutropenia is common during treatment with ZYDELIG and can sometimes be severe. Your doctor will check your blood counts regularly during treatment with ZYDELIG. Tell your doctor right away if you have a fever or any signs of an infection.

The most common side effects of ZYDELIG when used in combination with Rituxan include pneumonia, fever, feeling tired, rash, cough, and nausea.

What should I tell my doctor before taking ZYDELIG?

  • All of your medical conditions, including if you have liver, lung, or breathing problems or an infection.
  • If you are pregnant or plan to become pregnant. ZYDELIG may harm your unborn baby. Women who are able to become pregnant should use effective birth control (contraception) during treatment with ZYDELIG and for at least 1 month after the last dose of ZYDELIG. Talk to your doctor about birth control methods. Tell your doctor right away if you become pregnant or think you are pregnant during treatment with ZYDELIG.
  • If you are breastfeeding or plan to breastfeed. You and your doctor should decide if you will take ZYDELIG or breastfeed. You should not do both.
  • All the medicines you take, including prescription and over-the-counter medicines, vitamins, and herbal supplements. ZYDELIG and certain other medicines may affect each other.

You are encouraged to report negative side effects of prescription drugs to the FDA. Visit or call 1‑800‑FDA‑1088. You can also call 1‑800‑GILEAD‑5 (1‑800‑445‑3235).

Please see full Prescribing Information, including Medication Guide with important warnings.

Gilead, the Gilead logo, ZYDELIG, the ZYDELIG logo, and AccessConnect are trademarks of Gilead Sciences, Inc., or one of its related companies. Other brands noted herein are the property of their respective owners. © 2017 Gilead Sciences, Inc. All rights reserved. ZYDC0182 (02/2017)