Early Relapses in Primary CNS Lymphoma (PCNSL) without Intraventricular Treatment.

Background: A systemic and intraventricular polychemotherapy regimen (“Bonn protocol”) with deferred radiotherapy had resulted in durable responses in 75% of patients < 60 years with primary CNS lymphoma (PCNSL), but had been complicated by a high rate of Ommaya reservoir infections.

Purpose: Here, efficacy and toxicity of this regimen but without intraventricular treatment was evaluated in PCNSL.

Patients and Methods : From 08/03 to 11/05, 18 patients with PCNSL < 60 years (median age 53 years) were treated within a phase II trial with a high-dose methotrexate (MTX; cycles 1,2,4 and 5) and cytarabine (Ara-C; cycles 3 and 6) based systemic therapy including dexamethasone, vinca-alkaloids, ifosfamide and cyclophosphamide.

Results: Study accrual was prematurely stopped in 11/05 due to a high rate of early relapses. Seventeen/18 patients were assessable for response: Nine (53%) achieved complete response (CR), two (12%) complete response/unconfirmed (CRu), two (12%) partial response (PR), four (24%) showed progressive disease (PD); in one treatment was stopped due to toxicity. Median follow-up is 23 months; Kaplan-Meier estimates for median response duration were ten months only in responding patients and for median time to treatment failure (TTF) eight months in the whole group; median overall survival (OS) has not yet been reached. Systemic toxicity was mainly hematologic.

Conclusions: In patients < 60 years with PCNSL polychemotherapy without intraventricular treatment results in a high response rate, but is associated with early relapses in the majority of cases. This is in contrast to the results achieved with the same protocol but with inclusion of intraventricular treatment.