This study will evaluate the efficacy and safety of finite-duration acalabrutinib plus venetoclax therapy in patients with relapsed CLL or SLL, and have previously responded to first line (1L) cBTKi + BCL2i therapy (± obinutuzumab) and maintained a response for at least two years post-treatment.

The purpose of this study is to explore the use of second line (2L) treatment with AV after relapse following first line (1L) cBTKi + BCL2i by assessment of ORR in participants with CLL/SLL. This study will generate efficacy and safety data needed to understand outcomes associated with AV in patients who initially responded with partial remission (PR) or better for a minimum of 2 years from the end of 1L cBTKi + BCL2i combination treatment and are experiencing clinical relapse requiring further treatment. MAVRiC explores AV as second-line (2L) CLL/SLL treatment after relapse on first-line (1L) cBTKi + BCL-2 by assessment of overall response rate (ORR)

• The study duration for each participant will be up to 5 year.
• The study consists of screening, treatment, and post-intervention follow-up periods.
• Participants will be grouped into low or high risk cohorts based on disease risk determined by IGHV mutation and TP53 aberrancy.

Main Inclusion Criteria:

1. Participant must be ≥ 18 years at the time of signing informed consent.

2. Diagnosis of CLL/SLL according to iwCLL guidelines 2018 (Hallek et al. 2018)

3. Participants must have received first line treatment with fixed duration covalent BTKi plus BCL2i therapy (± obinutuzumab) with a response ≥ PR (i.e., CR, CRi, nPR, or PR) with a minimum of 2 years since the end of the prior 1L treatment.

4. The following data must be available or at least the appropriate samples drawn/acquired prior to dosing:

   1. IGHV (mutated vs. unmutated)
   2. del(17p) (present or absent)
   3. TP53 mutation (present or absent)

5. ECOG performance status 0, 1 or 2

6. Adequate organ and bone marrow (BM) function.

Main Exclusion Criteria:

1. Any evidence of diseases that, in the investigator's opinion, makes it undesirable for patient to participate in the study.
2. Significant cardiovascular or cerebrovascular disease.
3. Active bleeding or history of bleeding diathesis (e.g., hemophilia or von Willebrand disease).
4. Child-Pugh B/C liver cirrhosis.
5. History of prior or current malignancy.
6. HIV positive
7. History of progressive multifocal leukoencephalopathy (PML).
8. Active hepatitis B or C infection:
9. Corticosteroid use > 20 mg within 1 week before the first dose of study intervention.
10. History of hypersensitivity or anaphylaxis to study intervention(s).
11. Requires treatment with a strong CYP3A4 inhibitor/inducer.
12. Requires or receiving anticoagulation with warfarin or equivalent vitamin K antagonists.
13. Major surgical procedure within 30 days of the first dose of study intervention.

Qualified researchers can request access to anonymized individual patient-level data from AstraZeneca group of companies sponsored clinical trials via the request portal. All requests will be evaluated as per the AZ disclosure commitment: https://astrazenecagrouptrials.pharmacm.com/ST/Submission/Disclosure

AstraZeneca will meet or exceed data availability as per the commitments made to the EFPIA Pharma Data Sharing Principles. For details of our timelines, please rerefer to our disclosure commitment at https://astrazenecagrouptrials.pharmacm.com/ST/Submission/Disclosure.

When a request has been approved AstraZeneca will provide access to the de-identified individual patient-level data in an approved sponsored tool. Signed Data Sharing Agreement (non-negotiable contract for data accessors) must be in place before accessing requested information.