A Study Evaluating the Efficacy and Safety of Pirtobrutinib in Participants With Relapsed or Refractory Chronic Lymphocytic Leukemia/Small Lymphocytic Lymphoma

Inclusion Criteria:

• Have confirmed diagnosis of CLL/SLL as defined by iwCLL 2018 criteria.

• Part 1: Have received prior CLL/SLL treatment

• Have received at least 1, but not more than 3 lines of prior treatment for CLL/SLL

• Have received a covalent BTK inhibitor

• Part 2: Have received no prior treatment for CLL/SLL

• Part 1 - Known 17p deletion status (positive or negative)

• Part 2 - Must have 17p deletion (positive)

• Have a requirement for therapy consistent with iwCLL 2018 criteria for initiation oftherapy

• Capable of swallowing oral study medication.

• Have an Eastern Cooperative Oncology Group Performance Status (ECOG) score of 0 to

Exclusion Criteria:

• Have received prior treatment with a BTK degrader or a noncovalent BTK inhibitor

• Have a history of greater than or equal to (>=) Grade 3 bleeding due to treatmentwith 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 beforerandomization. Exceptions may occur with documented sponsor approval. Examplesinclude:

• nonmelanoma skin cancer or lentigo malignant melanoma

• cervical carcinoma in situ

• localized prostate cancer undergoing active surveillance, and

• localized (for example, lymph node negative) breast cancer with no evidence ofactive disease present for more than 3 years. Individual may be receivingadjuvant hormonal therapy