What are the first‑line treatment regimens for secondary central nervous system diffuse large B‑cell lymphoma (DLBCL) (non‑Hodgkin lymphoma)?

First-Line Treatment for Secondary CNS DLBCL

For secondary CNS DLBCL, treat with high-dose methotrexate (HD-MTX)-containing regimens as the backbone of therapy, followed by consolidation with autologous stem cell transplantation (ASCT) using thiotepa or BCNU-based conditioning in responding patients. 1

Treatment Algorithm Based on Clinical Presentation

For Synchronous CNS and Systemic Disease

When CNS involvement occurs at initial diagnosis alongside systemic DLBCL:

• Primary regimen: R-CHOP for systemic disease PLUS HD-MTX for CNS-targeted therapy 1
• Consolidation: Etoposide and cytarabine consolidation in patients achieving complete response in both CNS and systemic disease 1

For Isolated CNS Relapse (No Systemic Disease)

HD-MTX-based regimens are superior to other salvage approaches - treatment failures occurred in only 3/11 patients with HD-MTX versus 14/15 with other salvage chemotherapy/radiotherapy combinations 2

Specific HD-MTX-based options include:

• HD-MTX + high-dose cytarabine (demonstrated failure-free survival benefit) 1
• HD-MTX + ifosfamide + dexamethasone, followed by high-dose cytarabine + thiotepa (achieved 50% CR with 2-year OS of 68% post-transplant) 1
• HD-MTX + cytarabine, followed by R-HDS (rituximab, cyclophosphamide, cytarabine, etoposide) with ASCT (achieved 63% CR with 5-year OS of 68%) 1

For Combined CNS and Systemic Relapse

This scenario carries the worst prognosis - neither HD-MTX nor other treatments effectively reduced treatment failure rates (8/10 with HD-MTX, 23/30 with other treatments) 2. Systemic disease progression remains the main cause of death even in isolated CNS involvement, emphasizing the need for aggressive systemic control 2.

Special Considerations for Leptomeningeal Involvement

Add intrathecal liposomal cytarabine (IT LC) to HD-MTX regimens 1

• IT LC provides sustained CSF concentrations for 14 days versus conventional agents requiring 2-3 times weekly dosing 1
• Demonstrated superiority over conventional cytarabine in randomized trial for lymphomatous meningitis 1
• Alternative for synchronous disease: R-CHOP plus IT LC 1

Consolidation Strategy

For patients achieving response to induction, proceed with ASCT using thiotepa and/or BCNU in the conditioning regimen 1

This represents the best currently available curative option, with significantly better outcomes in patients achieving CR before transplantation 1.

Patients Unsuitable for HD-MTX

For elderly patients or those with significant comorbidities precluding HD-MTX:

Treat with intrathecal liposomal cytarabine (IT LC) alone 1

Critical Pitfalls to Avoid

1. Do NOT use R-CHOP alone - it does not cross the blood-brain barrier and will fail to control CNS disease 3

2. Assess MTX-sensitivity in relapsed disease - patients with MTX-resistant lymphoma or those relapsing within 6 months after consolidation are poor candidates for high-dose rescue strategies and should be considered for clinical trials or palliative treatment 1

3. Combined CNS and systemic relapse has dismal prognosis - even with intensive HD-MTX therapy, outcomes remain poor due to systemic progression 2

Emerging Therapies

While not yet standard first-line, CAR T-cell therapy shows efficacy in secondary CNS lymphoma without increased neurotoxicity 4, and newer bispecific antibodies (glofitamab, epcoritamab) are being investigated 5. However, these currently remain options for relapsed/refractory disease after standard approaches.

Strength of Evidence

The recommendations are based on Level B evidence from the Spanish Lymphoma Group (GELTAMO) 2017 guidelines 1, representing the most comprehensive guideline-based approach to secondary CNS DLBCL. No randomized controlled trials exist for this rare scenario, with current evidence derived from retrospective series and single-arm prospective studies 4, 2.