[1434] Plasma Cell Myeloma Evaluation by Flow Cytometric Immunophenotyping: Aberrant Antigen Expression and Correlation with Cytogenetic/FISH Abnormalities

Abbie L Husman, Michael Toscano, Katherine L Chandler, Sagar Lonial, Jonathan L Kaufman, Karen P Mann. Emory University, Atlanta, GA; Winship Cancer Institute of Emory University, Atlanta, GA

Background: Multiple myeloma (MM) is a disease of neoplastic plasma cells (PC). Patients demonstrate a variable disease course based in part upon underlying recurrent genetic abnormalities. Although mature PC typically demonstrate loss of most pan-B-cell antigens, MM PC often display aberrant expression of a variety of B-, myeloid- and T-associated antigens. In this study we examine the antigen expression profile in MM and correlate the immunophenotype with underlying genetic abnormalities.
Design: Four-color multiparameter flow cytometric immunophenotyping (FCI) results performed in the workup of MM patients at Emory University Hospital between 2006 and 2008 were reviewed. Cases demonstrating ≥5% clonal PC by FCI were selected. List-mode data were reanalyzed to evaluate the antigenic profile of MM PC. Positive antigen expression, defined as expression in ≥20% of gated PC, was compared with results of chromosome analysis and fluorescence in situ hybridization (FISH). Statistical analysis was performed using the Fisher's exact test to calculate a two-tailed P value. P values <0.05 were considered statistically significant. This study was approved by the Emory University Investigational Review Board.
Results: 96 patients meeting the study criteria were identified. Karyotype and FISH results were available for 82% and 73% of patients, respectively. B-lineage surface antigens were identified in 27% of patients. Expression of B-cell markers, particularly CD20 (18%), was associated with normal karyotype and negative FISH results (P = 0.008) and was uncommon in patients with del(13q), del(17p), t(4;14) and structural rearrangement of chromosome 1 (P = 0.027, 0.009, 0.048, and 0.042, respectively), known independent adverse prognostic markers in MM. In contrast, expression of the myeloid marker CD33 (19%) was associated with del(17p) and structural rearrangement of chromosome 1 (P = 0.035 and 0.025, respectively). There was no significant cytogenetic correlation observed with expression of T-cell markers, CD34, CD45, CD56, or CD117.
Conclusions: Our study demonstrates correlation of aberrant B-cell antigen expression with normal cytogenetics, and aberrant myeloid antigen expression with recurrent cytogenetic abnormalities in MM. Since these abnormalities are known to carry prognostic significance, FCI may be able to quickly provide supportive prognostic information for patients with MM. These findings may also help investigate the underlying biology of this disease.
Category: Hematopathology

Wednesday, March 21, 2012 1:00 PM

Poster Session VI # 229, Wednesday Afternoon

 

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