A Study of Pirtobrutinib (LOXO-305) Versus Bendamustine Plus Rituximab (BR) in Untreated Patients With Chronic Lymphocytic Leukemia (CLL)/Small Lymphocytic Lymphoma (SLL)

Inclusion Criteria: * Confirmed diagnosis of CLL/SLL requiring therapy, per iwCLL 2018 criteria * Eastern Cooperative Oncology Group (ECOG) Performance Status 0-2 * Adequate organ function * Platelets greater than or equal to (≥)75 x 10⁹/liter (L) (≥50 × 10⁹/L for patients with evidence of bone marrow infiltrate), hemoglobin ≥8 grams/deciliter (g/dL), and absolute neutrophil count ≥0.75 x 10⁹/L * Kidney function: Estimated creatinine clearance ≥40 milliliters per minute (mL/min) Exclusion Criteria: * Known or suspected Richter's transformation at any time preceding enrollment * Prior systemic therapy for CLL/SLL * Presence of 17p deletion * Central nervous system (CNS) involvement * Active uncontrolled auto-immune cytopenia (e.g., autoimmune hemolytic anemia \[AIHA\], idiopathic thrombocytopenic purpura \[ITP\]) * Significant cardiovascular disease * Active hepatitis B or hepatitis C * Active cytomegalovirus (CMV) infection * Active uncontrolled systemic bacterial, viral, fungal, or parasitic infection * Known human immunodeficiency virus (HIV) infection, regardless of cluster of differentiation 4 (CD4) count * Concurrent use of investigational agent or anticancer therapy except hormonal therapy * Patients requiring therapeutic anticoagulation with warfarin or another Vitamin K antagonist * Vaccination with a live vaccine within 28 days prior to randomization * Patients with the following hypersensitivity: * Known hypersensitivity, including anaphylaxis, to any component or excipient of pirtobrutinib or bendamustine * Prior significant hypersensitivity to rituximab