A Multicenter, Single-Arm, Open-Label, Phase II Trial of Mosunetuzumab in Combination With Tislelizumab for r/r FL

Inclusion Criteria:

1. Signed written informed consent.
2. Age ≥18 years.
3. Histologically confirmed relapsed/refractory follicular lymphoma (r/r FL).
4. Received at least two prior systemic therapies, including anti-CD20 monoclonal antibody therapy.
5. ECOG performance status 0-1.
6. Expected survival ≥12 weeks.
7. Measurable disease (longest diameter \>1.5 cm).
8. Adequate organ function:

   * Hepatic function: Total bilirubin ≤1.5×ULN; AST/ALT ≤3×ULN.
   * Hematologic function: ANC ≥1.5 × 10⁹/L; Platelets ≥75,000/μL; Hemoglobin ≥10.0 g/dL.
   * Renal function: Serum creatinine ≤1.5×ULN or CrCl ≥50 mL/min (Cockcroft-Gault formula).
9. Women of childbearing potential must have a negative serum pregnancy test and agree to use contraception.

Exclusion Criteria:

1. Inability to comply with study hospitalization and restrictions.
2. Active infections (including tuberculosis) or immunocompromised status.
3. Prior history of severe hypersensitivity to similar agents.
4. CNS involvement of lymphoma.
5. Pregnant or breastfeeding women.
6. Uncontrolled comorbid conditions, including cardiovascular or autoimmune diseases.
7. Receipt of live attenuated vaccines within 4 weeks before enrollment.
8. Use of systemic immunosuppressants within 2 weeks prior to first dose.
9. History of drug or alcohol abuse in the past 12 months.
10. Any condition deemed inappropriate for study participation by the investigator.