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FDA Approves New Type of BTK Inhibitor to Treat Mantle Cell Lymphoma

Rye Brook, N.Y., January 27, 2023 – The U.S. Food and Drug Administration today approved pirtobrutinib (Jaypirca™), the first non-covalent, reversable BTK inhibitor for the treatment of adults with mantle cell lymphoma that has worsened or returned despite earlier treatment. 

“Like all BTK inhibitors, this one works by suppressing Bruton’s tyrosine kinase, which malignant B-cells need to develop and grow,” says Lee Greenberger, Ph.D., LLS Chief Scientific Officer. “But its unique characteristics appears to avoid some of the resistance we see with covalent, irreversible BTK inhibitors, while still providing targeted treatment, meaning it zeros in on BTK causing fewer off-target side effects.”

The unique way pirtobrutinib works also means it may also be used in patients whose cancer has become resistant to earlier treatment with other BTK-targeting therapies such as ibrutinib or acalabrutinib. Mantle cell lymphoma is a particularly aggressive form of non-Hodgkin lymphoma with only short remissions from existing therapies, including BTK inhibitors.

LLS has funded research evaluating pirtobrutinib in combination with other medications as a first-line treatment for chronic lymphocytic lymphoma. LLS has also supported research to understand the mechanisms leading to pirtobrutinib resistance, when it occurs. 

Today’s FDA approval was based on results from the BRUIN clinical trial, which evaluated pirtobrutinib in 120 patients with mantle cell lymphoma who treated with pirtobrutinib once daily until the disease progressed or the patient experienced unacceptable toxicity. 

Half of the patients responded to treatment with 13% having a complete response, meaning their cancer was undetectable. The median time to a response to treatment was 1.8 months and the median duration of response was 8.3 months with 65% of patients who responded maintaining the response for at least 6 months.

The most common adverse reactions, which occurred in at least 15% of patients, were fatigue, musculoskeletal pain, diarrhea, fluid buildup (edema), shortness of breath, pneumonia and bruising. There were also several different high grade (severe) blood count abnormalities that occurred in at least 10% of study participants.

Newer BTK inhibitors are a promising therapeutic advance for mantle cell patients and likely for patients with other forms of B-cell cancer, like chronic lymphocytic leukemia, the most common type of leukemia in adults. LLS has millions of dollars committed to world-class research across the world working to find additional effective treatments to help patients with these recurrent and often aggressive cancers.