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Pirtobrutinib (LOXO-305)

Pirtobrutinib is an investigational, oral, highly-selective non-covalent Bruton’s tyrosine kinase (BTK) inhibitor. BTK plays a key role in the B-cell antigen receptor signaling pathway, which is required for the development, activation and survival of normal white blood cells, known as B-cells, and malignant B-cells. BTK is a validated molecular target found across numerous B-cell leukemias and lymphomas including chronic lymphocytic leukemia, mantle cell lymphoma, Waldenstrom’s macroglobulinemia, and marginal zone lymphoma.

Currently available BTK inhibitors irreversibly inhibit BTK and the long-term efficacy of these therapies can be limited by acquired resistance. Pirtobrutinib was designed to reversibly bind BTK, deliver consistently high target coverage regardless of BTK turnover rate, preserve activity in the presence of the C481 acquired resistance mutations, and avoid off-target kinases that have complicated the development of both covalent and investigational non-covalent BTK inhibitors.

Pirtobrutinib is currently being studied in multiple clinical trials. Safety and efficacy have not been established for the uses being studied.

For more information about the pirtobrutinib clinical trials, please refer to clinicaltrials.gov. Interested patients and physicians can contact 1-800-LillyRx (1-800-545-5979).