AUTOLOGOUS STEM CELL TRANSPLANTATION with INTRAVENOUS BUSULFAN, CYCLOPHOSPHAMIDE, and ETOPOSIDE as First-LINE TREATMENT of PRIMARY CENTRAL NERVOUS SYSTEM LYMPHOMA in a SINGLE CENTER.
Authors: Yoon Dok Hyun , Choi Dae Ro , Sohn Byeong Seok , Kim Shin , Lee Dae Ho , Kim Sang-We , Lee Jung Shin , Lee Sang-Wook , Huh Jooryung , Suh Cheolwon 
Published: October 2019

Abstract
Abstract 1219
Poster Board I-241

Background
High-dose chemotherapy followed by autologous stem cell transplantation (ASCT) has been evaluated in several trials and has shown feasibility as first-line treatment of primary central nervous system lymphoma (PCNSL). However, the best conditioning regimen is still to be identified and high-dose chemotherapy of busulfan, cyclophosphamide, and etoposide (BuCyE) has not been tried although the regimen was shown to be effective for leukemia and systemic non-Hodgkin's lymphoma.

Methods
Between May 2005 and November 2008, 12 consecutive patients of PCNSL with pathologic diagnosis of diffuse large-B cell lymphoma were treated with the intent of upfront ASCT at Asan Medical Center, Seoul, Korea. We retrospectively analyzed the results of these patients. The treatment included induction chemotherapy of high-dose methotrexate/cytarabine (Abrey et al., JCO 21:4151, 2003), followed by BuCyE chemotherapy consisting of iv busulfan (3.2mg/kg from day -7 to day -5), iv cyclophosphamide (50mg/kg from day -3 to day -2), and etoposide (200mg/m2 every 12 hours from day -5 to day -4), and ASCT. Whole brain radiotherapy (WBRT) was reserved for patients who failed to achieve complete response (CR) after ASCT.

Results
Median age was 50 years (range, 33-65) and 9 were male. The test of cerebrospinal fluid (CSF) cytology came out to be positive for 3 patients. Eight patients achieved CR and 4 gained partial response (PR) after induction chemotherapy. All 12 patients managed to complete ASCT. Following ASCT, additional 2 patients gained CR, resulting in total number of 10 patients (83.3%). Patients who failed to reach CR were further treated with WBRT and 2 more patients achieved CR. Median duration of first CR was 12.8 months (95% confidence interval [CI], 4.6-20.9) at a median follow-up of 23.8 months (range, 8.8-50.7). Relapse of disease occurred in 7 patients (58.3%) and 5 of them were given salvage treatment (Table 1). Two patients could regain CR and sustained remission for more than 2 years. Two patients had died of disease at the time of analysis. Median event-free survival (EFS) from the first day of induction chemotherapy was 15.0 months (95% CI, 8.3-21.8) and median overall survival (OS) was not reached. The 2-year OS probability was 78.8% and 2-year EFS was 25.7%. No patient experienced veno-occlusive disease or treatment-related mortality (TRM). Three patients among those who were treated with WBRT or intrathecal chemotherapy developed leukoencephalopathy.

Conclusion
BuCyE chemotherapy might be an option of conditioning regimen for ASCT considering high CR rate of 83.3% and favorable toxicity profile in the treatment of PCNSL. However, high relapse rate of 58.3% suggests that more optimization of induction and conditioning chemotherapy is still required.

Disclosures
No relevant conflicts of interest to declare.