Treatment patterns and disease course of previously untreated Primary Central Nervous System Lymphoma - feasibility of MTX-based regimens in clinical routine.

Background Primary Central Nervous System Lymphoma (PCNSL) is a rare type of aggressive lymphoma of the central nervous system. Treatment strategies improved significantly over the past decades, differ regionally but mainly consist of rituximab and high-dosed methotrexate (MTX)-based therapies. Methods We assessed clinical outcomes of 100 patients with newly diagnosed PCNSL between 2010-2020 at the University Hospital of Cologne, Germany. Results Patients were 23-88 years of age and either treated with MTX-based regimens (PRIMAIN, MARTA, MATRix), individual regimens or best supportive care, respectively. Overall response rates were generally high (66,7-83,8%), but different organ toxicities required dose adjustments in most groups. 2-year overall survival rates were 57,9% (PRIMAIN), 63,6% (MARTA), 65,4% (MATRix) and 37,5% (Other), respectively. Out of 9 patients suffering from relapse >12 months from primary diagnosis, 7 patients (77,8%) received methotrexate-based salvage therapy with 2-year overall survival of 4/6 patients (66,7%). Conclusion Although a relevant proportion of patients are not eligible for clinical trials due to age, performance status or comorbidities, these results prove feasibility of different MTX-based treatment strategies in clinical routine. Even elderly patients displayed surprisingly favorable outcomes. However, with compromising organ toxicities, reduction of intensity should be part of strategies in future clinical trials.