Target fluorescence in-situ hybridization (Target FISH) for plasma cell enrichment in myeloma

Abstract

BackgroundCytogenetic abnormalities are important prognostic markers in plasma cell myeloma (PCM) and detection is routinely performed by interphase fluorescence in-situ hybridization (FISH) with a panel of probes after enrichment of the plasma cells in the bone marrow specimen. Cell sorting by immunomagnetic beads and concurrent labeling of the cytoplasmic immunoglobulin are the usual enrichment methods. We present an alternative method of plasma cell enrichment termed Target FISH, which is an automated system that combines the images of May-Grünwald- Giemsa (MGG) staining and FISH study on the same plasma cell for analysis.ResultsOur experience of Target FISH on 40 PCM patients was described. Briefly, plasma cells were MGG stained, image captured, de-stained, FISH probe hybridized and finally relocated for simultaneous analysis of morphology and FISH signal pattern. The FISH probe panel was TP53/CEP17, t(4;14) IGH/FGFR3, t(14;16) IGH/MAF and CKS1B(1q21)/CDKN2C(P18). Gain of 1q21 was the most common abnormality detected in 18 patients (45 %), to be followed by t(4;14) IGH/FGFR3 detected in 11 patients (27.5 %). Of note, 10 patients showed coexistence of both t(4;14) and 1q21 gain. Two patients showed del(17p)/TP53, one in association with t(4;14) and 1q gain while the other was stand alone. None of this patient cohort showed t(14;16) IGH/MAF. Using the critical binomial function, the normal cutoff FISH positive value for del(17p)/TP53 was 3.4 %, t(4;14) IGH/FGFR3 was 6.8 %, t(14;16) IGH/MAF was 5.6 % and +1q21 was 5.7 %.ConclusionsThe equipment cost notwithstanding, when compared with cell sorting, the total reagent cost was around 10 % lower in Target FISH. The total processing time was longer for Target FISH but manual fluorescence microscopy was no longer necessary. The main advantage of Target FISH was the complete certainty that the cytogenetic abnormality was detected in the cells of interest, and hence a more stringent analytical cutoff value might be considered. Optimization of the cell collection and slide preparation process upfront was required to accrue adequate target cells on each slide for analysis. Our experience suggested that Target FISH was applicable as a routine method of plasma cell enrichment in clinical diagnostic laboratories.

Clinical implications of c-maf expression in plasma cells from patients with multiple myeloma

“…Data from recent studies in China also showed that the incidence of t(14;16) was only 0.8–6.7% among newly diagnosed MM patients [ 26 – 28 ], and the detection rate of t(14;16) was 1.2% in recently diagnosed MM patients [ 26 ]. A recent study from Hong Kong showed the absence of t(14;16) among 40 MM cases [ 29 ]. Translation of t(14;16) has also been observed in patients with MGUS, with the detection rate of approximately 5% [ 1 , 30 ], suggesting that the chromosomal translation may be involved in the early stages of the disease; however, its impacts on disease prognosis remains controversial.…”

Frequent functional activation of RAS signalling not explained by RAS/RAF mutations in relapsed/refractory multiple myeloma

“…Detection of cytogenetic abnormalities was performed on myeloma cells in the bone marrow by FISH, as previously described 38 . Interphase FISH was performed on slides for the examination of high-risk (HR) karyotypes, including t(4;14), t(14;16), del(17p), and amp(1q21), by IGH/FGFR3 DF FISH Probe kit (Vysis, USA), IGH/MAF DF FISH Probe kit (Vysis, USA), TP53/CEP17 FISH Probe kit (Vysis, USA), and CKS1B/CDKN2C (P18) amplification/deletion probe (Cytocell) respectively, in accordance with the International Myeloma Workshop Consensus recommendation.…”

A Comprehensive Review of the Genomics of Multiple Myeloma: Evolutionary Trajectories, Gene Expression Profiling, and Emerging Therapeutics

“…FISH, in contrast, requires the cell to be in interphase, the phase of the cell cycle in which the majority of cells are at in a given point of time [59]. FISH detection rate of cytogenetic abnormalities in plasma cell dyscrasia can further be enhanced with plasma cell enrichment, by increasing the number of the plasma cells collected in the bone marrow aspirate undergoing analysis [60][61][62].…”