BIOM-09. CLINICAL EFFECT OF CD25 ON THE MTX-BASED CHEMOSENSITIVITY OF PRIMARY CENTRAL NERVUS SYSTEM LYMPHOMA

Abstract INTRODUCTION Primary central nervous system diffuse large B-cell lymphoma (PCNSL) is treated with chemotherapy, mainly with high-dose methotrexate (HD-MTX), but some cases are resistant to treatment and relapse in a short period. However, a biomarker that predicts the chemosensitivity and recurrence has not yet been identified. In this study, we used surface marker analysis of tumor tissue using flow cytometry to search for biomarkers related to chemosensitivity and early recurrence. METHODS From 2017 to 2023, 25 patients were diagnosed with PCNSL by biopsy in Kobe University Hospital, and flow cytometry of the biopsy tissues were performed. Cerebrospinal fluid (CSF) examination including sIL2R, β2MG, and IL-10 was performed in all cases before surgery, and treatment based on methotrexate was administered postoperatively. We retrospectively analyzed patient characteristics, flow cytometry data, treatment details, response rate, time to recurrence, and overall survival. RESULTS The mean age of the patients was 71 (range, 37-80) years. In univariate analysis, high expression level of CD25 (interleukin-2 receptor, IL-2R) in the tissue was associated with a lower response rate to MTX-based chemotherapy (Fisher’s exact test, p=0.0072) and had a tendency of shorter time to recurrence. However, there were no significant differences in progression-free survival and overall survival. There was no correlation between expression level of CD25 in tissue and sIL-2R in CSF. Expression level of sIL-2R in CSF was independent of CD25 expression in tissue. CONCLUSION There are some reports that CD25 can be a prognostic factor in follicular lymphoma, but no reports in PCNSL. Here, we suggested that high expression level of CD25 in PCNSL tissue was associated to chemoresistance and early recurrence. In cases of PCNSL with high CD25 expression level, additional whole-brain irradiation and transition to tirabrutinib be considered because there are possibilities of chemoresistance and early recurrence.