How Does IMBRUVICA® (ibrutinib) Work?

HomeCLL/SLLHow Does IMBRUVICA® Work?

IMBRUVICA® Is an Oral, Once-Daily CLL/SLL Medicine That Works Differently Than Chemotherapy1,2

B cells need a protein called
Bruton’s tyrosine kinase (BTK) to survive.

BTK sends signals that help B cells stay alive and multiply. In CLL/SLL, some of these B cells are cancerous.

IMBRUVICA® binds to BTK, which in turn blocks these signals. This helps stop B cells, including cancerous B cells, from surviving and slows the spread of CLL or SLL.

B cells need a protein called
Bruton’s tyrosine kinase (BTK) to survive.

BTK sends signals that help B cells stay alive and multiply. In CLL/SLL, some of these B cells are cancerous.

IMBRUVICA® binds to BTK, which in turn blocks these signals. This helps stop B cells, including cancerous B cells, from surviving and slows the spread of CLL or SLL.

Because of how IMBRUVICA® works, it may cause side effects. A relationship between how IMBRUVICA® works and why it helps to treat CLL has not been clearly identified.

You may experience changes in your white blood cell count1,3 

After starting IMBRUVICA®, your doctor will perform blood tests to measure the kind and number of cells in your blood. Your lab results may show an increase in lymphocytes, a type of white blood cell. This is called lymphocytosis and can occur with IMBRUVICA® treatment. In the absence of other signs and symptoms, this increase may not necessarily mean your condition is worsening. 
 
In 3 IMBRUVICA® clinical trials, about 2 out of 3 (66%) people with CLL/SLL taking IMBRUVICA® developed lymphocytosis. This usually happened during the first month that people started taking IMBRUVICA®. How long lymphocytosis lasted varied. It went away by a median† of 14 weeks (range of less than 1 day to 26 months). 

†Median is the middle number in a group of numbers that are arranged from lowest to highest. For example, in the group of numbers 1-11, 6 is the median.

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IMBRUVICA® By Your Side patient support program is not intended to provide medical advice, replace prescribed treatment plans, or provide treatment or case management services. Patients are advised to talk to their healthcare provider and treatment team about any medical decisions and concerns they may have. By Your Side Registered Nurses are provided by Janssen Biotech, Inc. and Pharmacyclics LLC, an AbbVie Company, and do not work under the direction of your healthcare professional (HCP) or give medical advice. They are trained to direct patients to their HCP for treatment-related advice, including further referrals.

References: 1. IMBRUVICA® (ibrutinib) Prescribing Information. 2. National Institutes of Health. BTK gene. Accessed January 15, 2025. https://medlineplus.gov/genetics/gene/btk/ 3. Hallek M, Cheson BD, Catovsky D, et al. iwCLL guidelines for diagnosis, indications for treatment, response assessment, and supportive management of CLL. Blood. 2018;131(25):2745-2760.