High-dose methotrexate-based therapy

This project aims to establish and prospectively register a longitudinal, multimodal biobank for primary central nervous system lymphoma (PCNSL). The study will primarily enroll patients undergoing needle biopsy or surgical resection of lesions involving the brain, spinal cord, or meninges, with a pathological diagnosis of central nervous system lymphoma. To ensure population homogeneity, patients with PCNSL will constitute the core analysis cohort. Patients with imaging findings suggestive of PCNSL but a final pathological diagnosis other than PCNSL will serve as disease controls, and matched healthy volunteers will be recruited as baseline controls. At baseline, biopsy tissue, cerebrospinal fluid (CSF), peripheral blood, urine, saliva, and stool samples will be collected. Follow-up visits will be scheduled at 1 month after biopsy and every 3-6 months thereafter, with contrast-enhanced brain magnetic resonance imaging (MRI) and serial collection of CSF and peripheral blood. After the requirements of routine pathological diagnosis have been met, biopsy specimens will undergo tiered multi-omics profiling according to sample availability and freshness, including whole-exome sequencing, bulk RNA sequencing, single-cell RNA sequencing, metabolomics, spatial transcriptomics, and spatial metabolomics. Analyses of CSF and blood samples will focus on circulating tumor DNA and cell-free RNA (ctDNA/cfRNA), supplemented by conventional cytology, flow cytometry, and other clinical data for longitudinal disease monitoring. The project will develop an integrated database incorporating clinical, imaging, pathological, molecular, and biospecimen data. It will characterize the relationships of baseline tissue multi-omics features and longitudinal changes in CSF- and blood-derived ctDNA/cfRNA with treatment response, recurrence prediction, and prognosis. The study will also develop diagnostic and risk-stratification models applicable to patients at our institution, across the region, and potentially throughout mainland China, while establishing standardized operating procedures for biospecimen collection and processing. This work is expected to provide high-quality evidence and a sustainable translational research platform for elucidating the biological heterogeneity of PCNSL, validating liquid-biopsy biomarkers, and optimizing precision follow-up strategies.