The purpose of this study is to assess the efficacy and safety of APG-2575 single agent in patients with relapsed/refractory CLL/SLL.

This is an single-arm, open-label, multi-center, pivotal registration Phase II study of efficacy and safety of APG-2575 as a single agent in relapsed/refractory CLL/SLL patients.

This study plans to enroll approximately 75 CLL/SLL subjects who have failed or are intolerant to prior immunochemotherapy and BTK inhibitor therapy. Eligible subjects will receive APG-2575 600mg, orally administered once daily (QD), within half an hour of a low-fat meal, for a cycle of 28 days. Participants will continue to accept APG - 2575 until the "end of treatment" that are consistent with the provisions in the solution of the termination of any specified standards.

Inclusion Criteria:

Subjects who meet each of the following inclusion criteria are eligible to participate in this study:

1. Age ≥18 years old.
2. Pathologically confirmed CLL/SLL according to the 2018 revised IWCLL NCI-WG guidelines, subject with measurable lesions or splenomegaly due to CLL.
3. Expected survival is at least 12 weeks.
4. Refractory, recurrent, or intolerant to BTK inhibitors and immunochemotherapy,or first-line treatment with BTK inhibitors fails and is not suitable for immunochemotherapy.
5. Eastern Cooperative Oncology Group (ECOG) Performance Status (PS): 0 -2.
6. Ability to understand and willingness to sign a written informed consent form approved by EC committee (the consent form must be signed by the patient prior to any screening or study-specific procedures).
7. Willingness and ability to comply with study procedures and follow-up examination.

Exclusion Criteria:

Subjects who meet any of the following exclusion criteria are not to be enrolled in this study:

1. Prior history of allogeneic hematopoietic stem cell transplantation, adoptive cell immunotherapy or autologous hematopoietic stem cell transplantation within 24 months.

2. Failure to recover adequately, at the discretion of the investigator, from prior surgical procedures. Patients who have had major surgery within 28 days from study entry, and patients who have had minor surgery within 14 days of study entry.

3. Received Bcl-2 inhibitor treatment.

4. Invasive NHL transformation or central nervous system (CNS) involvement has occurred.

5. Pregnancy or lactation, or pregnancy is expected during the study period or within 3 months after the last administration of treatment.

6. Within 2 years before entering the study, the subject had a history of active malignant tumors other than CLL / SLL, except that:

   • Fully treated cervical carcinoma in situ;
   • Completely resected basal cell carcinoma of the skin or localized squamous cell carcinoma of the skin;
   • Confinement and resection of previously cured malignancies (or other treatment).

7. Any other condition or circumstance that would, at the discretion of the investigator, make the patient unsuitable for participation in the study.