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

Abstract

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 < 0.001 during the study period. Similarly, CALGB 50202 has the highest CR rate of 61.9% followed by R-MPV with CR rate of 16% followed by De-Angelis regimen with the lowest CR rate of 2.4%.CR rate comparison is statistically significant with P-value of < 0.0001. The study assessed optimum methotrexate dose. The mean and median total methotrexate dose in patients who were alive during the study period was 74.3 grams and 81.7 grams respectively as compared to mean value of 34.2 grams and median of 19.3 grams in patients who died with a p-value of 0.0019.Comparing survival based on histology as germinal center versus non-germinal center PCNSL, the later has higher mortality rate of 64.7 % as compared to 11.8 % in patient with germinal center PCNSL.Ki-67 was assessed as >80% and <80%.Among patients who were alive during the study period,48.8% have Ki-67 > 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.