Background: Primary NHL of the CNS (PCNSL) are associated with a dismal prognosis despite initial response to steroids and radiotherapy (RT). Addition of high-dose methotrexate (HD-MTX) to RT has improved the prognosis of patients (pts) with PCNSL. However, the majority of pts eventually relapse. To improve survival we performed a multicenter phase II study with early high-dose chemotherapy (HDT) and autologous stem-cell transplantation (ASCT) followed by hyperfractionated whole-brain radiation (WBRT) for 30 pts under 65yrs. Five-year overall survival rates of 69% for all pts and 87% for 23 pts receiving HDT and ASCT could be reported (Illerhaus et al., J Clin Oncol. 2006).

Purpose: Here we present the results of 1) a pilot study for HDT and ASCT with WBRT restricted to residual disease in pts ≤65 years; 2) a multicenter phase II study for MTX-based CT and 3) a pilot-study for chemo-immunotherapy in pts > 65 years.

Methods and Results:

  1. New treatment regimen for pts65 years: CT consists of 4 cycles HD-MTX (8g/m2), 2 cycles AraC (2×3g/m2) and thiotepa (40mg/m2) followed by HDT with BCNU (400mg/m2) and thiotepa (4×5mg/kg) before ASCT. To date, 12 pts have been treated in this single center pilot-study. After HDT and ASCT 7/10 pts (70%) responded with complete remission (CR), 2/10 pts with partial remission (PR), 1 pt showed progressive disease (PD) and died after refusing RT. The 2 pts with PR have been irradiated resulting in continuous CR. Two pts were off study due to refractory disease. After a median follow-up of 17 months (mo) (range 4–41) 9/12 pts are alive in continuous CR. One pt developed a systemic relapse and died 8 months after ASCT. Overall, the treatment was well tolerated without grade IV toxicity.

  2. Patients >65 yrs, MCP-protocol: Thirty-two pts (17 female, 15 male, median age 71 yrs, range 57–79y) were treated in a phase II trial with 3 repetitive cycles of HD-MTX (3g/m2, d1, 15, 30) combined with procarbazine (60 mg/m2 p.o., d1-10) and CCNU (110 mg/m2 p.o., d 1). There was no lower limit of Karnofsky Performance Status. Thirty-two pts received 1 cycle, 17 pts received 2 cycles and 10 pts received 3 cycles. Best documented response in 25 evaluable pts were CR in 13/32 (41%), PR in 7/32 (22%) and PD 5/32 (16%) pts. Five of 32 pts developed severe renal impairment after MTX and were treated off-study. One patient died due to neutropenic fever. With a median follow-up of 64 mo (range 0–82 mo), the 5-year overall survival probability currently is 30.5%, the median survival is 15 mo. As of July 2006 9/32 (28%) pts are alive, 8 without evidence for leukoencephalopathy.

  3. New treatment regimen for pts >65 years, R-MCP-Protocol: In a subsequent pilot-phase rituximab has been added before each MTX-application. In a single center pilot-phase, 9 pts were treated within the protocol. The response rates were CR in 4/7 (57%) evaluable pts, PR, SD and PD, each in one pt, respectively. One patient received only one dose of MTX due to liver toxicity and developed CR with rituximab as single agent. To date, after a median follow-up of 4 mo (range 0–11mo) 8 of 9 pts are alive.

Conclusion: The protocols presented here are safe and show high efficacy in treating patients with PCNSL in both age-groups. The addition of rituximab to MTX-based chemotherapy is promising and warrants further investigation.

Disclosure: No relevant conflicts of interest to declare.

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