Outcome of patients with primary CNS lymphoma treated with methotrexate based regimens: A retrospective study.

e19051 Background: Primary central Nervous system Lymphoma is an aggressive Non-Hodgkins Lymphoma with 5-year survival of only 30 percent. Few studies have addressed the comparison of induction treatment regimens with various risk stratification groups with no consensus on the optimal methotrexate dose for best complete overall response and survival outcome. Our retrospective study compares induction treatment regimens, identifies different risk stratification factors, and provides insight into the best induction treatment regimen with determination of optimal methotrexate dose. Methods: Design: Retrospective Primary Outcomes: Complete response rate, overall survival rate with risk stratification based on histology, Ki-67, and initial albumin level. Results: 77 patients 18 years of age and older with PCNSL at NCC and LAC between June 2015 and July 2022 were included in the study. Overall, 50% of patients were treated with CALGB50202 induction regimen,19% with R-MPV,12 % with De-Angelis regimen. CALGB 50202 has the highest survival rate of 63.4% followed by R-MPV with 22% survival rate followed by De-Angelis regimen with 0% survival rate with chi-square test P-value 80% and 80% as compared to only 12.2%.On the other hand, among the patients who died,47.1% of patients have Ki-67 <80%,indicating lower ki-67 associated a lower survival outcome as depicted on the Kaplan Meier curve with P-value of 0.004. Patients with normal initial albumin have a higher chance of survival (78%) vs 22% in the group with low albumin level with p-value of 0.0005. Conclusions: CALGB 50202 had the highest CR and survival rates followed by R-MPV regimen in patients with primary CNS lymphoma. The total dose of methotrexate patient receives was an important factor for survival and CR and the optimal total methotrexate dose was 70-80 grams. Normal initial albumin, high Ki-67, and germinal center histology favored better survival.