Prophylaxis with intrathecal or high-dose methotrexate in diffuse large B-cell lymphoma and high risk of CNS relapse

Although methotrexate (MTX) is the most widely used therapy for central nervous system (CNS) prophylaxis in patients with diffuse large B-cell lymphoma (DLBCL), the optimal regimen remains unclear. We examined the efficacy of different prophylactic regimens in 585 patients with newly diagnosed DLBCL and high-risk for CNS relapse, treated with rituximab, cyclophosphamide, doxorubicin, vincristine, and prednisone (R-CHOP) or R-CHOP-like regimens from 2001 to 2017, of whom 295 (50%) received prophylaxis. Intrathecal (IT) MTX was given to 253 (86%) and high-dose MTX (HD-MTX) to 42 (14%). After a median follow-up of 6.8 years, 36 of 585 patients relapsed in the CNS, of whom 14 had received prophylaxis. The CNS relapse risk at 1 year was lower for patients who received prophylaxis than patients who did not: 2% vs. 7.1%. However, the difference became less significant over time (5-year risk 5.6% vs. 7.5%), indicating prophylaxis tended to delay CNS relapse rather than prevent it. Furthermore, the CNS relapse risk was similar in patients who received IT and HD-MTX (5-year risk 5.6% vs. 5.2%). Collectively, our data indicate the benefit of MTX for CNS prophylaxis is transient, highlighting the need for more effective prophylactic regimens. In addition, our results failed to demonstrate a clinical advantage for the HD-MTX regimen.