Pirtobrutinib (LOXO-305) and Venetoclax for the Treatment of Patients With CLL or SLL Resistant to Covalent BTKi

PRIMARY OBJECTIVE: I. Determine if combination pirtobrutinib and venetoclax can induce undetectable minimal residual disease (uMRD) in CLL patients with resistance to ibrutinib, acalabrutinib, or zanubrutinib. OUTLINE: Patients receive pirtobrutinib orally (PO) once daily (QD) on days 1-28 of each cycle and receive venetoclax PO QD on days 1-28 of cycles 2-20. Cycles repeat every 28 days for up to 20 cycles in the absence of disease progression or unacceptable toxicity. Patients who experience disease progression within 12 months of stopping combination treatment may receive pirtobrutinib PO QD in the absence of disease progression or unacceptable toxicity. Additionally, patients undergo blood sample collection, bone marrow aspiration and biopsy and computed tomography (CT) throughout the study. After completion of study treatment, patients are followed up every 6 months.