LIBERTY: Liquid Biopsy to Diagnose and Monitor CNS Involvement in High-risk B Cell Non-Hodgkin Lymphoma

Inclusion Criteria: * Informed consent as documented by signature before registration and prior to any trial specific procedures, according to Swiss law and ICH E6 regulations Swiss law and ICH GCP E6(R2) regulations before registration. * Histologically and/or cytologically confirmed newly diagnosed lymphomas including the following: * Diffuse large B-cell lymphoma (DLBCL) with at least one of the following characteristics: * CNS IPI \> 4 * Non-GC/ABC subtype with IPI \> 3 * Testicular involvement * Breast involvement * Kidney involvement * Adrenal involvement * Paranasal sinus / orbit involvement * Involvement of ≥ 3 extranodal sites * HIV-positive * Radiological or histological CNS involvement * High-grade B-cell lymphoma with MYC translocation with BCL2 and / or BCL6 (HGBL) * Burkitt lymphoma * Mantle cell lymphoma (blastoid variant or Ki67 \>30% or TP53 mutated) * Primary CNS lymphoma Note: * Aggressive transformation from indolent lymphomas (pretreated or not) are allowed * Patients enrolled in other clinical trials may be included * Patients must be willing to undergo a lumbar puncture at screening * Age ≥ 18 years Exclusion Criteria: * Subtypes of Non-Hodgkin lymphoma (NHL) not fulfilling above mentioned criteria (e.g., indolent lymphoma, T-cell lymphoma) * Relapsing B-NHL * Low/intermediate-risk DLBCL (CNS-IPI \< 4) AND no CNS involvement on imaging * Any prior lymphoma-directed therapy before registration, with the exception of a maximum of 48 hours steroids prior to lumbar puncture procedure and therapies received for indolent lymphomas prior to transformation * Any active advanced or metastatic cancer * Any clinical contraindication to lumbar puncture procedure as per local guidelines * Any other serious underlying medical, psychiatric, psychological, familial or geographical condition, which in the judgment of the investigator may interfere with the planned diagnostic procedure.