Efficacy and safety of prophylactic high-dose MTX in high-risk DLBCL: a treatment intent-based analysis.

Despite central nervous system (CNS) relapse occurring in >10% of high-risk diffuse large B-cell lymphoma (DLBCL) patients, the role of CNS-directed prophylaxis is controversial in the absence of randomized controlled trials. In this retrospective study, we aimed to evaluate the safety and efficacy of prophylactic high-dose methotrexate (HD-MTX) on CNS relapse and survival outcomes in 258 newly diagnosed R-CHOP (rituximab, cyclophosphamide, doxorubicin, vincristine, and prednisone)-treated high-risk DLBCL patients, based on the initial treatment intent (ITT) of the physician on the use of prophylactic HD-MTX. Patients were classified into an ITT HD-MTX group (n = 128) and a non-ITT HD-MTX group (n = 130). The CNS relapse rate was not significantly different between these groups, with 2-year CNS relapse rates of 12.4% and 13.9%, respectively (P = 0.96). Three-year progression-free survival and overall survival rates in the ITT HD-MTX and non-ITT HD-MTX groups were 62.4% vs 64.5% (P = 0.94) and 71.7% vs 71.4% (P = 0.7), respectively. Also, propensity score-matched analyses showed no significant differences in the time-to-CNS-relapse, progression-free survival, or overall survival. The ITT HD-MTX group showed a higher incidence of grade ≥ 3 oral mucositis and elevated alanine aminotransferase. Prophylactic HD-MTX does not improve CNS relapse rate or survival outcomes in high-risk DLBCL patients, and it is accompanied by increased toxicities.