CTNI-64. MATRIX REGIMEN FOR NEWLY DIAGNOSED PRIMARY DIFFUSE B-CELL LYMPHOMA OF THE CENTRAL NERVOUS SYSTEM

We report our experience treating 16 patients with newly diagnosed primary diffuse B-cell lymphoma of the central nervous system with the MATRix regimen as reported by Ferreri, et al in 2016. The median age was 66 years (y); 8 patients were men and 8 were women. Fourteen had cerebral mass lesions, 1 had a paraspinal mass, and 1 leptomeningeal disease. Treatment consisted of 4 cycles of rituximab 375 mg/sq m (Days 1, 6); methotrexate 3.5 g/sq m (Day 2); cytarabine 2 g/sq m every 12 h (Days 3, 4); and thiotepa 30 mg/sq m (Day 5). Patients without disease progression received carmustine 400 mg/sq m and thiotepa 4 X 5 mg/kg followed by autologous bone marrow transplantation. Four patients were switched to MATRix after 6 cycles of methotrexate and rituximab and received only 2 initial cycles including cytarabine and thiotepa. Overall, 12 patients completed initial chemotherapy. Eleven of these 12 went on to transplantation; one patient had early disease progression and did not proceed to transplantation. All 4 patients over 70 y died early after 1–2 cycles; the median age of these was 80 y, and the causes of early death were neutropenic fever, septic thrombophlebitis, and cardiac arrest. One patient who completed the entire regimen including transplantation died of fungal pneumonia; the other 11 experienced no serious acute toxicity. One patient had late disease progression; one developed symptomatic leukoencephalopathy. Nine of the 16 patients remain alive. At a median follow-up of 23 months, median time to progression was 421 days and overall survival 564 days. These preliminary data suggest that the MATRix regimen in safe and highly effective in the newly diagnosed setting. However, the high incidence of early death in patients over 70 y suggests that the regimen may be too toxic for elderly individuals.