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FDA Approves New Drug for the Most Common Form of Leukemia in Adults


Rye Brook, N.Y., December 8, 2023 – The U.S. Food and Drug Administration has approved pirtobrutinib (Jaypirca™) for the treatment of adults with chronic lymphocytic leukemia (CLL) or small lymphocytic lymphoma (SLL) that has worsened or returned despite at least two earlier forms of treatment. Pirtobrutinib was approved earlier this year for the treatment of relapsed/refractory mantle cell lymphoma.

Pirtobrutinib is the only FDA-approved non-covalent, reversable Bruton’s tyrosine kinase (BTK) inhibitor. LLS funded early research that uncovered how certain cancer cells use BTK to develop and grow. Drugs that reduce levels of BTK have since revolutionized treatment of B-cell lymphomas such as CLL, SLL and mantle cell.

“Previously approved BTK inhibitors selectively bind but also chemical link to BTK, which we call a covalent linkage,” explains Lee Greenberger, Ph.D., LLS Chief Scientific Officer. “Pirtobrutinib selectively binds to BTK in a distinct manner and is not dependent upon chemical linkage to BTK. These distinctions explain why pirtobrutinib remains an option when covalent inhibitors such as ibrutinib or acalabrutinib stop working.”

LLS is supporting new clinical studies that will help determine the optimal sequence for the use of pirtobrutinib and other BTK inhibitors, as well as combinations with other effective therapies for CLL such as venetoclax or obinutuzumab, says Dr. Greenberger.

In addition, LLS is supporting studies to define the mechanism of resistance to pirtobrutinib, as it is anticipated that the disease will ultimately stop responding to pirtobrutinib in some patients. All of this work is leading to more effective and safer treatments of CLL that could ultimately provide a cure for the disease.

The FDA’s approval was based on results from the BRUIN clinical trial, which evaluated pirtobrutinib in 108 patients with CLL or SLL who received at least two earlier treatments, including a BTK inhibitor. Patients in the trial received anywhere from 2 to 11 prior treatments.

More than 7 in 10 patients in the trial responded to treatment with pirtobrutinib. The median duration of their response was just over a year and the progression-free survival was approximately 20 months.

The challenge, according to Dr. Greenberger, is that patients whose disease has progressed after earlier lines of treatment often face a poor prognosis with limited treatment options. 

“The FDA’s approval of pirtobrutinib gives these patients a much-needed new option,” he says.