Abstract 2666

Background:

CD25 (the alpha chain of the IL-2 receptor) has been shown to be expressed in a small subset of normal B cells and hairy cell leukemia cells; however, its expression in diffuse large B-cell lymphoma (DLBCL) has not been examined. The aim of this study was to clarify the clinical features of CD25+ DLBCL. Patients and Methods: Fifty-five patients with newly diagnosed CD25+ DLBCL who were admitted to our hospital between 1993 and 2011 were retrospectively evaluated. Lymph node or related tissue biopsy specimens from the patients were analyzed using FCM combined with single- and two-color staining. CD25 expression was defined as positivity of >20% of clonal B cells with CD19 or 20 expression >80% in a gated region. Results: There were 30 males and 25 females, with a median age of 65 years (range, 27–88 years). They showed aggressive clinical features as follows: 37 patients older than 60 (67%), 45 with elevated LDH (82%), 42 with soluble IL-2 receptor higher than 2,000 U/ml (79.4%), 33 with advanced-stage disease (stage III or IV, 60%), 28 with more than one extra nodal site (51%), 31 at high/high-intermediate risk according to the international prognostic index (IPI) score (56.4%). Chromosomal abnormalities were identified in 27 (79.4%) of 34 patients and frequently at chromosomes 3 (n = 13), 6, 7, 8, 14 (n = 9, respectively), and 1 (n = 7). CD25 expression showed a mean of 60.2% (range, 21.2–97.4%), and was particularly higher in patients aged more than 65 years and with CNS involvement (66.8 vs. 52.8%, p= 0.03 and 88.2 vs. 61.8%, P <0.01, respectively). In two-color FCM analysis, the percentages (mean ± SD) of CD19+CD25+ and CD20+CD25+ cells were 63.7 ± 25.5% (n=13) and 55 ± 28.1% (n=14), respectively. Compared to the patients with de novo CD25+ follicular lymphoma (CD25>20%, CD19/20>80%, n = 7), CD25 expression was significantly higher in CD25+ DLBCL (59.1%) than in CD25+ follicular lymphoma (34.5%). The complete remission (CR), 4-year progression free survival (PFS) and overall survival rates in the patients treated with R-CHOP (n = 35) were 81, 47, and 64%, respectively. When CD25 expression levels were compared between patients in CR and alive and those in non-CR and deceased, a trend was shown (58.1 vs. 74.4%, P = 0.055, and 57 vs. 71.8%, P = 0.058, respectively). Conclusion: CD25+ DLBCL may constitute a distinct subgroup with aggressive clinical features. Because R-CHOP is less effective for these patients, an alternative approach such as R-CHOP + anti-CD25 immunotherapy is needed.

Disclosures:

No relevant conflicts of interest to declare.

Author notes

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Asterisk with author names denotes non-ASH members.