Background: Optimal consolidative therapy for primary central nervous system lymphoma (PCNSL) is not defined. Avoidance of whole brain radiation may reduce risk of neurotoxicity. Non-radiation consolidative options include myeloablative chemotherapy followed by autologous stem cell transplantation (HDT/ASCT) or non-myeloablative chemotherapy. Methods: This is a randomized phase 2, National Clinical Trials Network study of induction methotrexate (MTX) (8 g/m²days 1, 15), temozolomide (TMZ) (150-200 mg/m² D7-11), and rituximab (RTX) (C1 D3, 10, 17, 24 and C2 D3, 10) in four 28-day cycles followed by one cycle of cytarabine (ARA-C) (2 g/m² BID, D1, 2) (MTRA). Following induction, patients (pts) received consolidation with thiotepa (5 mg/kg BID, D -5, -4) plus carmustine (400 mg/m², day -6) and ASCT (Arm A) or one cycle of ARA-C (2 g/m² BID, D1-4) plus infusional etoposide (40 mg/kg over 96h) (Arm B). The primary endpoint was median progression-free survival (PFS), designed to compare consolidation regimens. This report describes the results of the 5 cycles of induction therapy. Results: 113 pts (median age 61 years, range 33-75) were randomized (Arm A: 57, Arm B: 56) across 27 centers. 108 eligible pts who received induction therapy were evaluated. 36 pts (33.3%) did not proceed to consolidation, mainly due to disease progression (17), pt withdrawal (8), or adverse events including death (6). Grade 3 or 4 febrile neutropenia occurred in 12 pts (11.1%) during induction. Dose modifications of MTX were required in 75% of pts and 63.3% of cycles, mainly due to renal adjustments. Dose delays of MTX were required in 52.8% of pts and 22.2% of cycles. Overall response rate (CR, CRu, PR) at the end of induction was 65.7% (95% CI, 56%, 74.6%). Conclusions: While MTRA is feasible and active a significant proportion of pts did not receive consolidation, supporting the need to develop more effective induction strategies. Clinical trial information: NCT01511562.