Global Trial in APG2575 for Patients With CLL/SLL

Inclusion Criteria: 1. Age ≥ 18 years. 2. Patients that have documented CLL/SLL who meet iwCLL 2018 criteria for CLL treatment guidelines are eligible for treatment and must be receiving BTKi monotherapy for at least 12 months 3. ECOG Performance Status grade 0-2 4. Adequate bone marrow function independent of growth factor or transfusion support within 2 weeks of screening initiation as follows: * Absolute neutrophil count ≥ 1.0 × 109/L * Platelet counts ≥ 75 × 109/L; in cases of thrombocytopenia * Total hemoglobin ≥ 9 g/dL, 5. Adequate renal function * Creatinine clearance must be \> 50 ml/min directly measured with 24hr urine collection or calculated according to the modified formula of Cockcroft and Gault (for men: GFR ≈ ((140 - age) x actual body weight)/(72 x creatinine), for women x 0.85) or an equally accurate method. * For patients with creatinine values within the normal range, the calculation of clearance is not necessary. Dehydrated patients with an estimated creatinine clearance less than 50 ml/min may be eligible if a repeat estimate after adequate hydration is \> 50 ml/min. 6. Adequate liver function as indicated by: * Total bilirubin ≤ 1.5 x ULN, except patients with known Gilbert's Syndrome * Aspartate aminotransferase (AST) ≤ 2.5 x the institutional ULN value * Alanine aminotransferase (ALT) ≤ 2.5 x the institutional ULN value, * International normalized Ratio (INR), Prothrombin Time (PT) or Activated Partial Thromboplastin time (APTT) ≤ 1.5×ULN. 7. Ability and willingness to provide written informed consent and to adhere to the study visit schedule and other protocol requirements