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Background: CD44 variants have been implicated in metastasis and as an unfavorable prognosis factor in many types of cancers. Our previous study had showed that CD44v6 expression implied a poor clinical outcome in diffuse large B cell lymphoma (DLBCL) patients treated with CHOP. However, it is remains unknown the prognostic value in DLBCL patients treated with R-CHOP due to our sample sizes. Therefore, to examine the prognostic value of CD44v6 expression in DLBCL patients, we performed this retrospective study. Methods: All 141 patients diagnosed as de novo DLBCL according to WHO classification were further confirmed. All patients treated with R-CHOP (rituximab plus cyclophosphamide, doxorubicin, vincristine, and prednisone). The expression of CD44v6 was analyzed by immunohistochemistry (IHC). IHC was performed by an automated immunostainer complying with the instructions of the protocols. Results: Among all the 141 patients, the expression of CD44v6 was observed in 41 cases (29.1%). CD44v6 is expressed predominantly in non-germinal center type DLBCL. There was no significant difference in gender, age, B symptoms, performance status, LDH, stage and IPI score between patients with and without CD44v6 expression. Patients with CD44v6 expression showed significant inferior overall survival, but not event-free survival compared with CD44v6-negative patients. (p=0.022 and p=0.142, respectively).Multivariate analysis showed that the expression of CD44v6, independent of the international prognostic index and cell of origin, implied a poor overall survival (HR=2.223; 95% CI= 1.007-4.906, p=0.048), but not event-free survival (HR=1.457; 95% CI=0.773-2.745, p=0.245). Conclusions: These data suggest that the expression of CD44v6 implied poor outcome in DLBCL patients treated with R-CHOP. Disclosures No relevant conflicts of interest to declare.

Purpose To establish a method for detecting minimal residual disease (MRD) by eight color flow cytometry which is stable, repeatable and accurate quantitation. Method According to the ratio of 10%, 1%, 0.1%, 0.01% and 0.001%,to analyze sensitivity of the method by successively mixing the cell lines (Kasumi, KG-1a) and primary acute leukemic bone marrow cell were mixed with normal bone marrow cells. In order to ensure the specificity of the test results, we increased antibody number to eight color combinations of antibodies to adjust fluorescence compensation value after labeling antibody separately in each channel. To verify the feasibility of standardization, standardized test were in 25 bone marrow samples of acute leukemia. Result In standard conditions of detection and sensitivity of 10-5could be detected by eight color flow cytometry. In our study there were 25 cases of acute leukemia, including 14 patients with acute myeloid leukemia and 11 patients with acute B-lymphoblastic leukemia. 23 of 25 cases were detected specific leukemia associated immunophenotypes (LAIP) at diagnosis. 20 patients could be detected the original LAIP, and LAIP of 3 patients changed after remission induction therapy. To analyze the relationship between the clinical data and MRD level, the result showed that the type of LAIP had significant influence on level of MRD. After remission the level of MRD in patients who expressed cross lineage and non-synchronous antigens at diagnosis was significantly higher than those who did not express (P=0.003, P=0.006). Conclusion We established the standardized conditions of minimal residual disease detected by multiparametric flow cytometry to ensure the accuracy and specificity of the test results. It has important significance to confirm that manifestations of LAIP were consistent with the outcome in patients with acute leukemia. Disclosures No relevant conflicts of interest to declare.