Myeloablative Versus Non-Myeloablative Consolidation for Primary Central Nervous System Lymphoma: Results of Alliance 51101

While it is evident that standard dose whole brain radiotherapy as consolidation is associated with significant neurotoxicity, the optimal consolidative strategy for primary central nervous system lymphoma (PCNSL) is not defined. We performed a randomized phase 2 clinical trial via the U.S. Alliance cancer cooperative group to compare myeloablative consolidation supported by autologous stem cell transplantation with non-myeloablative consolidation after induction therapy for PCNSL. This is the first randomized trial to be initiated that eliminates whole brain radiotherapy as a consolidative approach in newly-diagnosed PCNSL. Patients, age 18-75 years, were randomly assigned in a 1:1 manner to induction therapy (methotrexate, temozolomide, rituximab and cytarabine) followed by consolidation with either thiotepa plus carmustine and autologous stem cell rescue versus induction followed by non-myeloablative, infusional etoposide plus cytarabine (EA) The primary endpoint was progression-free survival (PFS). 113 patients were randomized and 108 (54 in each arm) were evaluable. More patients in the non-myeloablative arm experienced progressive disease or death during induction (28% versus 11%, p = 0.05). Thirty-six patients received autologous stem cell transplant and 34 received non-myeloablative consolidation. The estimated 2-year PFS was higher in the myeloablative versus non-myeloablative arm (73% versus 51%; p= 0.02). However, a planned secondary analysis, landmarked at start of consolidation, revealed that the estimated 2-year PFS in those who completed consolidation therapy was not significantly different between the arms (86% versus 71%; p = 0.21). Both consolidative strategies yielded encouraging efficacy and similar toxicity profiles.Clinicaltrials.gov (NCT01511562)