How BTK Inhibitors Changed the CLL Treatment Paradigm
- A class of targeted drugs known as BTK inhibitors transformed chronic lymphocytic leukemia (CLL) treatment, allowing many patients to avoid chemotherapy in favor of better-tolerated oral drugs.
- Despite the success, first-generation BTK inhibitor ibrutinib is limited by cardiac side effects. Second‑generation BTK inhibitors (acalabrutinib, zanubrutinib) are generally more effective and better tolerated, yet resistance can still develop, often due to what’s known as a C481 mutation.
- A more recent option, pirtobrutinib (Jaypirca), a non‑covalent BTK inhibitor, works differently and can overcome C481‑related resistance. Dr. Vikas Bhushan, a hematologist-oncologist with Texas Oncology, tells SurvivorNet that about two‑thirds of BTK‑resistant patients respond and the drug is typically well-tolerated.
- BTK inhibitors can cause side effects like early digestive issues, easier bruising/bleeding, and occasional heart rhythm changes.
- Most side effects are manageable or improve over time, and patients who struggle with one BTK inhibitor may be able to switch to another.
“The first BTK inhibitor approved was a drug called ibrutinib, which is a very popular drug and was a major breakthrough in CLL, but had problems mainly with cardiac side effects,” Dr. Vikas Bhushan, a hematologist-oncologist with Texas Oncology at Medical City Dallas, tells SurvivorNet.
Read MoreSecond-Generation BTK Inhibitors
BTK inhibitors have dramatically improved outcomes for many patients, but at some point — usually many years later — their disease may eventually progress.Second-generation BTK inhibitors have since become available and are “probably more efficacious” than ibrutinib, Dr. Bhushan explains.
Expert Resources for CLL Patients
- After the Initial CLL Diagnosis: The First Conversation
- BTK Inhibitors Play An Important Role In CLL Treatment & Management
- BTK Inhibitors for CLL Treatment: What Side Effects Can I Expect and How Do I Manage Them?
- BTK Inhibitors: Monitoring and Managing Side Effects During CLL Treatment
- Changing the Way CLL is Treated: What are BTK Inhibitors?
BTK inhibitors fall into two main categories based on how they attach to the BTK protein.
Covalent BTK inhibitors — including ibrutinib (Imbruvica), acalabrutinib (Calquence), and zanubrutinib (Brukinsa) — bind permanently to the protein, while non-covalent BTK inhibitors, such as pirtobrutinib (Jaypirca), attach in a reversible way.
Jaypirca: A ‘Non-Covalent’ BTK Inbitor
Dr. Bhushan describes the newer drug, pirtobrutinib (Jaypirca), as working through a fundamentally different mechanism.
“It’s called reversible binding to the receptor,” he explains, noting it can be used in patients who are resistant to, or intolerant of, first-line BTK inhibitors.
Pirtobrutinib, which is taken as a once-daily pill, has shown encouraging results in patients whose CLL has progressed after treatment with a previous BTK inhibitor, as this drug binds in a different way.
“The most common reason why a BTK inhibitor stops working is the development of a mutation called C481. And this drug [pirtobrutinib] is effective against patients with that mutation,” Dr. Bhushan adds.
Dr. Bhushan estimates that “almost two out of three patients who are resistant to first-line BTK will respond to this drug” — roughly a 67% response rate — and adds that, in his experience, the drug is “fairly well tolerated.”
Questions To Ask Your Doctor
- Which BTK inhibitor do you recommend in my case?
- Should I consider a combination therapy?
- What potential side effects should I be monitoring for at home?
- What are my options if my CLL continues to progress?
Learn more about SurvivorNet's rigorous medical review process.
