Orelabrutinib Followed by Response-adapted Ultra-low Dose 4Gy Radiation as First-line Treatment of MALT Lymphoma

Inclusion Criteria:

• Age ≥ 18 years old

• Histologically confirmed mucosa-associated lymphoid tissue (MALT) lymphoma

• Lugano stage I-II

• ECOG 0-2

• Signed informed consent

• Having sufficient organ function: a) Hematopoietic function: Neutrophils ≥ 1.0 × 109/L, PLT ≥ 50 × 109/L, Hb ≥ 80g/L; b) Liver function: bilirubin ≤1.5 times theupper limit of normal (ULN), ALT and AST<3 x ULN, serum albumin ≥ 30 g/L; c) Renalfunction: serum Cr<1.5 × ULN, creatinine clearance rate ≥ 50mL/min (calculatedaccording to the standard Cockcroft Gault formula, if renal dysfunction is caused bytumor compression, creatinine clearance rate ≥ 30mL/min); d) Coagulation function (unless the subject is receiving anticoagulant therapy and the coagulationparameters (PT/INR and APTT) are within the expected range of anticoagulant therapyat the time of screening): International standardized ratio (INR) ≤ 1.5 x ULN;Activated partial thromboplastin time (APTT) ≤ 1.5 x ULN.

Exclusion Criteria:

• Recent major surgery (within 4 weeks prior to enrollment), except for diagnosticsurgery

• Have uncontrolled intercurrent diseases (cardiovascular and cerebrovasculardiseases, coagulation disorders, severe infectious diseases) including but notlimited to: severe acute or chronic infection requiring systemic treatment,symptomatic congestive heart failure (NYHA III-IV) or symptomatic or poorlycontrolled arrhythmias, arterial hypertension (systolic blood pressure ≥ 160mmHg ordiastolic blood pressure ≥100mmHg) that is not controlled even with standardtreatment, unstable angina, active peptic ulcer or bleeding disorder;

• Severe concomitant diseases that interfere with treatment

• Active interstitial pneumonia

• Active chronic hepatitis B infection (defined as HBV DNA positive; patients withlatent or prior hepatitis B infection (defined as positive for hepatitis B surfaceantigen or hepatitis B core total antibody) can be included if HBV-DNA isundetectable at screening. The above-mentioned patients must voluntarily undergoregular DNA tests and receive appropriate antiviral therapy as prescribed)

• Positive hepatitis C test result (for patients who are positive for HCV antibodies,only polymerase chain reaction (PCR) shows a negative HCV RNA can participate)

• Patients with active HIV and syphilis infections;

• Pregnant or lactating women

• Patients with multiple factors affecting oral medication (such as dysphagia, nausea,vomiting, chronic diarrhea, and intestinal obstruction)

• The researcher determined that patients are not suitable to participate in thisstudy.