HOW DO BRUTON TYROSINE KINASE INHIBITORS WORK?

Bruton’s tyrosine kinase inhibitors (BTKIs) are oral targeted therapies that block the activity of Bruton’s tyrosine kinase (BTK), an enzyme that plays a key role in the development and function of B cells, a type of white blood cell. Overactivity of BTK can drive certain blood cancers, such as chronic lymphocytic leukemia (CLL) and mantle cell lymphoma (MCL), as well as autoimmune and inflammatory diseases like chronic immune thrombocytopenia (ITP).

By inhibiting BTK, these drugs slow abnormal B-cell growth, reduce the production of harmful antibodies, and help control inflammation while preserving most normal immune functions.

The first FDA-approved BTKI was ibrutinib, used for B-cell cancers and chronic graft-versus-host disease (cGVHD). Newer drugs such as acalabrutinib, zanubrutinib, and pirtobrutinib have expanded treatment options. Most recently, in August 2025, rilzabrutinib (Wayrilz) was approved for adults with persistent or chronic ITP who have not responded to other therapies, the first BTKI approved outside of oncology.

BTK inhibitors are oral medicines, available as tablets or capsules, usually taken once or twice daily. They are primarily used to treat various B-cell cancers, including:

• Chronic lymphocytic leukemia/small lymphocytic lymphoma (CLL/SLL)
• Mantle cell lymphoma (MCL)
• Waldenström macroglobulinemia (WM)
• Marginal zone lymphoma (MZL)
• Follicular lymphoma (FL)

Some BTK inhibitors have other approved uses. Ibrutinib (Imbruvica) is also used for chronic graft-versus-host disease (cGVHD). More recently, rilzabrutinib (Wayrilz) was approved for adults with persistent or chronic immune thrombocytopenia (ITP) who have not responded to prior therapies, marking the first BTK inhibitor approval outside of oncology.

Common side effects of Bruton tyrosine kinase inhibitors include the following:

• Diarrhea
• Nausea
• Headache
• Abdominal pain
• Fatigue
• Muscle or joint pain
• Low white blood cell count (neutropenia)
• Upper respiratory tract infections (such as cough or cold)
• Decreased appetite
• Weakness
• Nosebleed

Information contained herein is not intended to cover all possible side effects, precautions, warnings, drug interactions, allergic reactions, or adverse effects. Check with your doctor or pharmacist to make sure these drugs do not cause any harm when you take them along with other medicines. Never stop taking your medication and never change your dose or frequency without consulting your doctor.

Generic and brand names of FDA-approved Bruton tyrosine kinase inhibitors include:

• acalabrutinib
• Brukinsa
• Calquence
• ibrutinib
• Imbruvica
• Jaypirca
• pirtobrutinib
• rilzabrutinib
• Wayrilz
• zanubrutinib