B-220 Clinical Application of the “Clg-Fish” Technique for the Diagnosis of Multiple Myeloma

Abstract Background The international standard system R2-ISS for Multiple Myeloma (MM) includes genetic characteristics of malignant cells by fluorescent in situ hybridization -t(4;14), del(17p) and t(14;16) at diagnosis; We included interphase fluorescent in situ hybridization (cIg-FISH) of purified CD138 cells in this evaluation. The aim of this study is to evaluate the implementation of cIg-FISH in MM for disease diagnosis and stratification. Methods oBone marrow BM from patients with MM diagnosed by the European Myeloma Network (REM) criteria were evaluated. BM mononuclear cells obtained by density gradient centrifugation for 30 minutes, with Ficoll-Hypaque density medium; followed by immunoassay with anti-Kappa/anti-Lambda antibodies labeled with FISH probes. We detected the following abnormalities: t(4;14), t(14;16) and deletion of 17p13. The t(11;14) and the amplification/deletion of 1q21-q22 (CKS1B)/1p32.3 (CDKN2C). We used the probes: TP53, IGH::FGFR3, IGH::CCND1, IGH:MAF and CKS1B/CDKN2C, one hundred cells per probe. Signals exceeding the cutoff recommended by REM were considered abnormal. The viability of the method was tested on samples 24, 48 and 72 hours after collection. Results Genetic aberrations seen in 24 and 48 hs plasma cells, a specific rearrangement of 14q32.33 t(4;14) in the 48 hs sample; Samples processed for 72 hours resulted in cells that were unviable for analysis. Genetic aberrations were detected by cIg-FISH in cells from 40% of patients. We detected the following abnormalities t(4;14) (Fig.1A), del(17p) (Fig. 1B); deletion of 1p32.3 amplification (CDKN2C) 1q21 (Fig. 1 C-D). The cIg-FISH study detected genetic aberrations in MM as those recommended by the European Myelomat Network - t(4;14), t(14;16) and del(17p), by FISH analysis for risk stratification for MM. Conclusions The inclusion of cIg-FISH in risk stratification systems has clinical relevance because cIg-FISH is a standard tool for detecting genetic abnormalities and prognosing the disease.