BTK Inhibitors

Bruton tyrosine kinase inhibitors (BTK inhibitors) are cancer medicines that block the enzyme Bruton’s tyrosine kinase (BTK). BTK is part of the B-cell receptor pathway. This is a signaling system that tells B cells (a type of white blood cell) when to grow and survive.

Normally, B cells use this signaling system to stay healthy and make antibodies. These are important for fighting infections and diseases. But in certain cancers, abnormal B cells take over this system and grow out of control.

BTK inhibitors act as a roadblock by shutting down the receptor pathway. This stops the abnormal B cells from multiplying.

Researchers are also studying BTK inhibitors in autoimmune diseases like multiple sclerosis (MS). The goal is to calm overactive immune cells.

What conditions do BTK inhibitors treat?

BTK inhibitors are FDA-approved for certain white blood cell cancers or immune system conditions, including:

• Chronic graft versus host disease
• Chronic lymphocytic leukemia
• Mantle cell lymphoma
• Marginal zone lymphoma
• Small lymphocytic lymphoma
• Waldenström’s macroglobulinemia

BTK inhibitors and multiple sclerosis

Researchers are studying how BTK inhibitors may help manage multiple sclerosis as a type of disease-modifying therapy. This isn’t an available treatment option yet. But you may be able to try clinical trials.

Here’s what they found so far. BTK inhibitors turn down signals in certain immune cells. These cells can attack the myelin. Myelin is the protective coating around nerves. BTK inhibitors help calm your immune system in places where MS damage starts.

When those immune cells are less active, there may be less inflammation in your brain and spinal cord. Early studies show people taking some BTK inhibitors had fewer new “active” spots on MRI scans. This is a sign of lower inflammation.

What are the types of BTK inhibitors?

There are different BTK inhibitors approved by the U.S. Food and Drug Administration (FDA). The FDA-approved uses for these medications may differ. Your healthcare provider may offer:

• First generation (ibrutinib): It attaches to the enzyme BTK but also affects other enzymes. This makes side effects more common.
• Second generation (acalabrutinib and zanubrutinib): These bind more selectively to BTK. They work just as well as the first generation, but may cause fewer side effects.
• Third generation (pirtobrutinib): It binds differently to BTK compared to the previous generations and may help even if the cancer becomes resistant to first- or second-generation BTK inhibitors.

How should I take BTK inhibitors?

You should follow your prescribing instructions for taking these medications. They vary by type and dosage.

BTK inhibitors are oral medications. That means they come in a tablet or capsule form. You’ll swallow it whole, with water. You can take it with or without food.

You should store these medications at room temperature. They should also be away from children and pets.

If you have any questions about when or how to take this medication, contact your pharmacist or prescribing provider.

BTK inhibitor side effects

Some common side effects are:

• Diarrhea
• Skin rash
• Fatigue
• Muscle or joint aches
• Easy bruising
• Headache

Side effects can vary between the different BTK inhibitors.

These drugs may increase the risk of the following:

• An irregular heart rhythm
• Bleeding
• Electrolyte abnormalities
• High blood pressure
• Infections

Can I drink alcohol with BTK inhibitors?

It is recommended to avoid or limit alcohol while taking a BTK inhibitor. Alcohol can increase the risk of side effects seen with BTK inhibitors. Alcohol can raise your risk of bleeding and high blood pressure. It may also lead to abnormal heart rhythms.

Can I take BTK inhibitors if I’m pregnant or thinking of becoming pregnant?

You shouldn’t take BTK inhibitors during pregnancy. They may harm the fetus. Tell your healthcare provider if you’re planning to have children. They can adjust your treatment plan to help keep you and the fetus safe.

BTK inhibitor interactions

The following may interact with BTK inhibitors:

• Antiplatelets (like aspirin, clopidogrel)
• Blood thinners (warfarin)
• Grapefruit and Seville oranges
• Heart medicines (diltiazem, verapamil)
• St. John’s wort

This isn’t an inclusive list of medications and supplements that can interact with BTK inhibitors. Tell your healthcare provider about all the medicines and supplements you take now or plan to take. This helps them check for serious drug interactions that could harm your health.

You’ll also want to inform your dentist that you’re taking this medication before a dental procedure. Your dentist may want you to temporarily stop the medication before the procedure and, in some cases, for a brief time afterward.