Lisaftoclax Plus Pirtobrutinib in Relapsed or Refractory Mantle Cell Lymphoma After BTK-Targeted Therapy

This prospective, open-label, phase 2 study will evaluate the efficacy and safety of lisaftoclax in combination with pirtobrutinib in adults with relapsed or refractory mantle cell lymphoma following failure of prior BTK-targeted therapy. The study includes two cohorts. Cohort 1 will enroll participants who experienced stable disease, disease progression, or intolerance following treatment with a covalent BTK inhibitor. Cohort 2 is an exploratory cohort enrolling participants who experienced stable disease, disease progression, or intolerance following treatment with a non-covalent BTK inhibitor other than pirtobrutinib or a BTK degrader. Participants will receive oral pirtobrutinib 200 mg once daily in combination with oral lisaftoclax. Lisaftoclax will be administered using a dose ramp-up schedule, followed by a target dose of 600 mg once daily. Treatment will continue until disease progression, unacceptable toxicity, withdrawal of consent.

Inclusion Criteria: * Participants must meet all of the following criteria: 1. Age 18 years or older. 2. Histologically and immunophenotypically confirmed mantle cell lymphoma. 3. At least one measurable lesion. 4. Received at least one prior systemic treatment regimen that included a BTK-targeted therapy, including a covalent BTK inhibitor, non-covalent BTK inhibitor, or BTK degrader, and had stable disease, disease progression, or intolerance during or after the most recent BTK-targeted therapy. 5. Eastern Cooperative Oncology Group performance status of 0 to 2. 6. Adequate hepatic, renal, and bone marrow function, defined as all of the following: \* Aspartate aminotransferase and alanine aminotransferase ≤3 × upper limit of normal; * Total bilirubin ≤1.5 × upper limit of normal; * Creatinine clearance ≥30 mL/min; * Absolute neutrophil count ≥0.5 × 10\^9/L; * Platelet count ≥30 × 10\^9/L. Supportive treatment is permitted. 7. Participants of reproductive potential must agree to use effective contraception during study treatment and for 3 months after the last dose of study treatment. 8. Willing and able to comply with study procedures and follow-up assessments. 9. Able to understand and voluntarily sign the informed consent form before screening. Exclusion Criteria: * 1\. Known hypersensitivity to pirtobrutinib, lisaftoclax, or any component or excipient of either study drug. 2\. Concurrent participation in another clinical study. 3. Prior treatment with any BCL-2 inhibitor. 4. Active central nervous system involvement, including parenchymal or leptomeningeal disease. 5\. Clinically significant uncontrolled cardiac or cardiovascular disease, or a history of myocardial infarction within 6 months before the planned initiation of pirtobrutinib. 6\. Uncontrolled active severe systemic bacterial, viral, fungal, or parasitic infection. 7\. Current treatment with strong CYP3A4 inhibitors or inducers and/or strong P-glycoprotein inhibitors. 8\. Positive human immunodeficiency virus test. 9. Active hepatitis B or hepatitis C infection, except: * Participants with detectable hepatitis B virus DNA whose disease is controlled may be enrolled at the investigator's discretion, provided that concurrent antiviral therapy is administered; * Participants with a history of hepatitis C virus infection who have completed antiviral treatment and have a viral load below the lower limit of quantification may be enrolled. 10\. Pregnant or breastfeeding women. 11. Unable to complete protocol-required study visits or procedures, including follow-up visits, or unable to comply with study requirements. 12\. Any other clinically significant current or prior medical condition that, in the investigator's judgment, may pose a risk to participant safety or interfere with study assessments, procedures, or completion.