A Phase 3 Open-Label, Randomized Study of LOXO-305 Versus Investigator's Choice of Idelalisib Plus Rituximab or Bendamustine Plus Rituximab in BTK Inhibitor Pretreated Chronic Lymphocytic Leukemia/Small Lymphocytic Lymphoma (BRUIN CLL-321)

• Confirmed diagnosis of CLL/SLL requiring therapy as defined by iwCLL 2018 criteria.

• Previously treated with a covalent BTK inhibitor.

• Eastern Cooperative Oncology Group (ECOG) 0-2.

• Absolute neutrophil count ≥ 0.75 × 10\^9/L without granulocyte-colony-stimulating factor support, or ≥ 0.50 × 10\^9/L in patients with documented bone marrow involvement considered to impair hematopoiesis. Granulocyte-colony-stimulating factor support is permitted in patients with documented bone marrow involvement.

• Hemoglobin ≥ 8 g/dL or ≥ 6 g/dL in patients with documented bone marrow involvement considered to impair hematopoiesis. Transfusion support is permitted in patients with bone marrow involvement.

• Platelets ≥ 50 × 10\^9/L. If an investigator has chosen bendamustine/rituximab as the Arm B treatment, platelets must be ≥ 75 × 10\^9/L. Patients may enroll below these thresholds if the Investigator determines the cytopenia is related to bone marrow involvement considered to impair hematopoiesis. Patients with a platelet count \< 30 x 10\^9/L are excluded.

• AST and ALT ≤ 3.0 x upper limit of normal (ULN).

• Total bilirubin ≤ 1.5 x ULN.

• Estimated creatinine clearance of ≥ 30 mL/min.