BRUIN: This study is recruiting people with relapsed or refractory chronic lymphocytic leukaemia or small lymphocytic lymphoma (CLL/SLL) to assess how safe and effective different dose levels of a targeted cancer drug called Pirtobrutinib isA Phase 2, Open-Label, Randomized Study Evaluating the Efficacy and Safety of 3 Doses of Pirtobrutinib in Participants With Relapsed or Refractory Chronic Lymphocytic Leukemia/Small Lymphocytic Lymphoma Who Previously Received Treatment With a Covalent Bruton Tyrosine Kinase Inhibitor

Exclusion

• Have received prior treatment with a BTK degrader and a noncovalent BTK inhibitor
• Have a history of greater than or equal to (>=) Grade 3 bleeding due to treatment with a BTK inhibitor
• Have known or suspected Richter's transformation
• Have known or suspected history of central nervous system involvement by CLL/SLL

• Previous or concurrent cancer distinct from CLL/SLL within 3 years before randomization. Exceptions may occur with documented sponsor approval. Examples include:

  • nonmelanoma skin cancer or lentigo maligna melanoma
  • cervical carcinoma in situ
  • localized prostate cancer undergoing active surveillance, and
  • localized (for example, lymph node negative) breast cancer with no evidence of active disease present for more than 3 years. Individual may be receiving adjuvant hormonal therapy