High-dose methotrexate and rituximab with deferred radiotherapy for newly diagnosed primary B-cell CNS lymphoma

We conducted a prospective Phase II study of high-dose methotrexate (HD-MTX) and rituximab with deferred whole brain radiotherapy in patients with newly diagnosed B-cell primary central nervous system lymphoma with a primary objective of evaluating progression-free survival (PFS). Forty patients (25 men; 15 women), ages 18–93 years (median 61.5), were treated. All patients received biweekly HD-MTX/rituximab (8 g/m²/dose; 375 mg/m²/dose) for 4–6 cycles (induction) and following best radiographic response, with every 4 weeks HD-MTX (8 g/m²/dose) for 4 cycles (maintenance). Neurological and neuroradiographic evaluation were performed every 4 weeks during induction therapy and every 8 weeks during maintenance therapy. All patients were evaluable. A total of 303 cycles of HD-MTX (median 8 cycles; range 4–10) was administered. HD-MTX/rituximab-related toxicity included 16 grade 3 adverse events in 13 patients (32.5%). Following induction, 8 patients (20%) demonstrated progressive disease and discontinued therapy; 32 patients (80%) demonstrated a partial (8/40; 20%) or complete (24/40; 60%) radiographic response. At the conclusion of maintenance therapy (6–10 months of total therapy), 28 patients (70%) demonstrated either a partial (1/28) or complete (27/28) response. Overall, survival of these 28 patients ranged from 11 to 80 months (median 33.5). Survival in the entire cohort ranged from 6 to 80 months with an estimated median of 29 months. Overall, PFS ranged from 2 to 80 months (median 21.0). HD-MTX/rituximab and deferred radiotherapy demonstrated similar or better efficacy similar to other HD-MTX-only regimens and reduced time on therapy on average to 6 months.