Pomalidomide, Anti-PD-1 Antibody Combined With Selinexor (PPS) in Relapsed/Refractory Primary Central Nervous System Diffuse Large B-Cell Lymphoma

Inclusion Criteria:

* Histologically confirmed primary central nervous system diffuse large B-cell lymphoma (PCNSL-DLBCL).
* Disease progression or relapse after prior treatment with high-dose methotrexate and/or BTK inhibitors.
* Age between 18 and 75 years.
* ECOG performance status score 0-4.
* Expected overall survival \> 3 months.
* No known hypersensitivity to any study drug.
* White blood cell count ≥ 3×10⁹/L; absolute neutrophil count ≥ 1.0×10⁹/L; platelet count ≥ 50×10⁹/L.
* Serum creatinine ≤ 1.5 mg/dL; creatinine clearance ≥ 50 mL/min.
* ALT and AST ≤ 3× upper limit of normal (ULN); total bilirubin ≤ 2× ULN.
* Signed written informed consent.

Exclusion Criteria:

* Presence of another malignant tumor requiring active pharmacological or surgical intervention at present;
* Female patients who are pregnant or breastfeeding;
* Patients (male or female) of reproductive potential who are unwilling to use or fail to use effective contraceptive measures;
* Known hypersensitivity to any study drug or any excipient ingredients of these products;
* Active infection (determined by the investigator);
* History of immunodeficiency, including positive HIV status, other acquired or congenital immunodeficiency disorders, or history of organ transplantation;
* Documented history of neurological or psychiatric disorders, including epilepsy or dementia;
* Documented history of autoimmune diseases (except Hashimoto's thyroiditis or thyroid dysfunction);
* Any severe comorbidity that, in the investigator's judgment, would compromise patient safety or interfere with the completion of the study.