A Multicenter, Prospective Clinical Trial With a Concurrent Control Evaluating Methotrexate Combined With Rituximab,Sintilimab and Pirtobrutinib vs. Investigator-Selected Standard of Care in Treatment-Naive PCNSL

In Treatment-Naive Patients With Primary Central Nervous System Lymphoma (PCNSL): A Multicenter, Prospective, Concurrent-Control Study of Methotrexate, , Rituximab,, Sintilimab ,Pirtobrutinib Versus Investigator-Selected Standard of Care

The goal of this clinical trial is to evaluate the efficacy and safety of a four-drug combination regimen as first-line treatment for adults aged 18 years and older with newly diagnosed primary central nervous system lymphoma (PCNSL). The main questions it aims to answer are:

Does the combination of pirtobrutinib, sintilimab, rituximab, and high-dose methotrexate achieve a higher complete response rate than standard treatment for newly diagnosed PCNSL? What is the safety and tolerability profile of this four-drug combination regimen? Researchers will compare the experimental four-drug combination to investigator-selected standard-of-care regimens (all based on high-dose methotrexate) to see if the experimental regimen improves complete response rate, progression-free survival, and overall survival while maintaining an acceptable safety profile.

Participants will:

Be assigned to either the experimental group or the standard treatment group based on their personal preference Receive 6 cycles of induction therapy (21 days per cycle) with their assigned treatment regimen Undergo regular clinical assessments, including contrast-enhanced brain MRI scans, blood tests, and cerebrospinal fluid examinations Complete the EORTC QLQ-C30 quality-of-life questionnaire at baseline, mid-treatment, end of treatment, and follow-up visits Receive optional consolidation or maintenance therapy based on their response to induction treatment Be followed for up to 2 years after completing treatment to monitor for disease progression and long-term outcomes

Primary Central Nervous System Lymphoma (PCNSL) is a rare extranodal non-Hodgkin lymphoma with poor prognosis, characterized by MYD88 L265P/CD79B mutations and PD-L1/PD-L2 overexpression. Current first-line therapies based on high-dose methotrexate (HD-MTX) have limitations including high recurrence rates, poor blood-brain barrier penetration, and significant toxicity. Pirtobrutinib, a highly selective reversible BTK inhibitor, exhibits superior CNS penetration and safety profiles compared to covalent BTK inhibitors. Sintilimab (anti-PD-1) enhances anti-tumor immunity by blocking PD-1/PD-L1 axis. This study evaluates the efficacy and safety of the quadruple combination (methotrexate+rituximab + sintilimab + pirtobrutinib ) in treatment-naive PCNSL, with a concurrent control cohort providing comparative evidence.

Inclusion Criteria:

1. Age >= 18 years.
2. Voluntarily signed informed consent.
3. ECOG Performance Status 0-3.
4. Expected survival > 3 months.
5. Histopathologically confirmed Diffuse Large B-Cell Lymphoma (DLBCL) restricted to the CNS or eyes (PCNSL).
6. Measurable lesion on contrast-enhanced MRI (>10x10 mm) or positive CSF cytology for leptomeningeal disease.
7. No prior systemic treatment for lymphoma (corticosteroids excepted).
8. Adequate bone marrow and organ function (ANC >=1.5x10^9/L, PLT >=80x10^9/L, Hb >=80 g/L; Bilirubin <=1.5xULN, AST/ALT <=2.5xULN; Creatinine <=1.5xULN or CrCl >=60 mL/min) .
9. Stable controlled comorbidities allowed (e.g., hypertension with blood pressure <=160/100 mmHg, type 2 diabetes with HbA1c <=8%, mild coronary heart disease without myocardial infarction in the past 6 months).
10. Basic communication ability to complete PROs questionnaires (no severe cognitive impairment).
11. Reproductive-aged females and males with childbearing potential: No pregnancy plans during the study and 3 months after treatment discontinuation; use effective contraception (abstinence, physical contraception, or hormonal contraceptives initiated >=3 months before first dose). Males prohibited from donating sperm during treatment and 3 months after discontinuation.
12. For Observational Cohort (Palliative Care Subgroup only): Pathologically confirmed DLBCL restricted to the CNS or eyes; Follow-up available for efficacy assessment (at least one CR evaluation) .

Exclusion Criteria:

1.Prior treatment with PD-1/PD-L1 inhibitors or CTLA4 monoclonal antibodies. Uncontrolled active infection. 2.Uncontrolled or significant cardiovascular diseases: 3.Congestive heart failure (NYHA class III/IV),

1. myocardial infarction, unstable angina within 6 months before first dose; arrhythmia requiring treatment; LVEF <50%.
2. Primary cardiomyopathy.
3. History of clinically significant QTc prolongation, second-degree type II/third-degree atrioventricular block, or QTc interval (Fridericia method) >470 msec (females) / >480 msec (males).
4. Atrial fibrillation (EHRA grade ≥2b).
5. Refractory hypertension. 4.Active hepatitis B/C infection (HBV-DNA ≥ detection limit, HCV RNA positive) or syphilis. (Exceptions: HBV-DNA < detection limit, cured HCV).

5.HIV infection. 6.Prior organ transplantation or allogeneic stem cell transplantation. 7.Pregnant or lactating females. 8.Prior/current pulmonary fibrosis, interstitial pneumonia, pneumoconiosis, or radiation pneumonitis (unsuitable for study per investigator).

9.Autoimmune diseases requiring systemic treatment within 2 years. 10.For Observational Cohort (Palliative Care Subgroup only): Incomplete clinical data (e.g., no pathological report, inability to perform MRI/PET-CT assessment).