El-Galaly, Tarec C.

PURPOSE In large B-cell lymphoma (LBCL), use of high-dose methotrexate (HD-MTX) to prevent CNS relapse (so-called CNS prophylaxis) remains controversial. International guidelines continue to recommend HD-MTX in patients deemed ultra high risk (UHR) because of a lack of robust data specific to these subgroups. This study was designed to examine the impact of HD-MTX specifically in UHR patients. METHODS Data from two previous retrospective analyses were combined to produce a cohort of UHR patients (≥1 of the following criteria: CNS international prognostic index score 5-6; testicular, renal/adrenal, or breast involvement; ≥3 extranodal sites), treated with or without HD-MTX. The primary outcome was CNS relapse rate (isolated or concurrent with systemic relapse) measured from diagnosis with additional landmark analysis of all responding patients with no progression event at 6 months. RESULTS Analyses were performed on 1,923 patients meeting UHR criteria. No significant difference in 3-year CNS relapse rate was observed between no HD-MTX (n = 1,051) versus HD-MTX patients (n = 872), including in multivariable analyses adjusting for baseline characteristics (3-year rate, 9.3% v 8.1%; adjusted hazard ratio [HR], 1.13 [95% CI, 0.82 to 1.57]). Analyses restricted to isolated CNS relapse also confirmed no difference (5.9% v 5.7%; adjusted HR, 1.03 [95% CI, 0.69 to 1.53]). In the landmark analysis (no HD-MTX n = 782, HD-MTX n = 773), no difference in 3-year CNS relapse was observed (6.7% v 6.6%, adjusted HR, 0.95 [95% CI, 0.62 to 1.44]). CONCLUSION To our knowledge, this is the largest international comparative data set of patients with LBCL with UHR features showing no significant reduction in CNS relapse with HD-MTX in all UHR or in any individual subgroup. Despite inherent limitations of retrospective analyses, the data strongly support previous studies in suggesting HD-MTX prophylaxis has no meaningful benefit for most patients.

ABSTRACT One quarter of patients with diffuse large B‐cell lymphoma (DLBCL) who achieve a complete response following front‐line therapy will eventually experience disease relapse. Existing prognostic models use baseline factors to predict outcomes from the start of initial therapy and are not intended for use following completion of treatment. We developed a conditional event‐free survival (cEFS) tool that predicts a patient's risk of lymphoma recurrence after completing front‐line therapy taking into consideration baseline risk characteristics plus the time the patient has been in remission. Model development used pooled and harmonized data from two observational cohorts and four randomized trials of patients with newly diagnosed DLBCL treated with immunochemotherapy and either achieving a complete response or not experiencing an event within 12 weeks of end of therapy. Cox proportional‐hazards regression modeling with backwards stepwise selection was utilized for model development. External validation was performed using a large independent data registry. In total, data from 2757 patients were used for model development. The risk of experiencing an event at a time point after having survived a period of time could be computed parsimoniously using four basic predictors: age, ECOG performance status grade, Ann Arbor stage, and lactate dehydrogenase level. C‐index in the model development cohort was 0.65 (95% CI, 0.63–0.68), compared to 0.64 (95% CI, 0.62–0.66) in the external validation cohort. We believe that this dynamic risk prediction tool will not only aid clinicians in providing data‐driven recommendations for surveillance, but also assist patients themselves with key decisions, such as family planning.