Rituximab, methotrexate (MTX), procarbazine, and vincristine (R-MPV) followed by consolidation high-dose chemotherapy (HDC) and autologous stem-cell transplant (ASCT) for newly diagnosed primary CNS lymphoma (PCNSL).

Abstract

2008 Background: In our previous study in newly diagnosed PCNSL, induction chemotherapy with MTX and cytarabine followed by consolidation HDC (carmustine, etoposide, cytarabine, melphalan [BEAM]) with ASCT without radiotherapy resulted in only 50% of pts transplanted, reflecting low efficacy of induction chemotherapy, and short intent-to-treat (ITT) median PFS (=6m). In this phase II trial, we sought to optimize this strategy by utilizing a more effective induction regimen (R-MPV) and a more aggressive HDC regimen (Soussain et al). Methods: Pts received 5-7 cycles of R-MPV (MTX: 3.5g/m2) and if a partial or complete response was achieved, HDC with thiothepa, cyclophosphamide and busulfan was given, followed by ASCT and no radiotherapy. The primary endpoint was ITT 1 year event-free survival (promising: 75%, non-promising: 50%; 90% power, significance=0.05). Follow-up included comprehensive neuropsychological evaluation. Results: Accrual has been completed (N=32 pts, median age 57 [range 23-67], median KPS=80). Following R-MPV, 17 pts achieved a CR, 13 pts a PR and two pts progressed. A total of 25 (78%) pts were transplanted; the reasons for not receiving transplant were progressive disease (N=2), poor performance status/ physician’s decision (N= 2), mobilization failure (N=1) and consent withdrawn (N= 2). One pt who withdrew consent relapsed and received HDCASCT for salvage. Two (8%) pts died from early complications of ASCT (Stevens-Johnson: one, sepsis: one) and one pt experienced a fatal late colitis of unknown etiology. In the ITT population, the median EFS and OS have not been reached after a median follow-up of 22 months. The 1 year EFS was 78% (95%CI 58-90) and the 2y OS was 76% (95% CI 54-89). No pt has developed delayed neurotoxicity. Conclusions: R-MPV induction regimen resulted in improved response rates, allowing 78% of pts to receive HDC-ASCT. Although more toxic, this regimen resulted in excellent disease control and survival in the ITT population, far exceeding the efficacy of our previous transplant study. The primary endpoint was met, warranting further investigation.