CD34+ FISH As a New Method for Molecular-Cytogenetic Diagnostic From Peripheral Blood in MDS: Update of the Multicenter German Prospective Diagnostic Study

Conventional chromosome banding (CCB) analyses of bone marrow (bm) metaphases represent the gold standard of cytogenetic diagnostics in myelodysplastic syndromes (MDS), but they are not suitable for frequent follow-up analyses. Most aberrations can also be detected by fluorescence in situ hybridisation (FISH), and they are provable in CD34+ cells from peripheral blood (pb). In our prospective multicenter German diagnostic study “Screening and genetic monitoring of patients with MDS under different treatment modalities by cytogenetic analyses of circulating CD34+cells” (ClinicalTrails.gov NCT01355913) we followed MDS pts by sequential FISH analyses.

CD34+ pb cells were enriched by immunomagnetic cell sorting (MACS®) and analysed by FISH using a “Superpanel” (D7/CEP7, EGR1, CEP8, CEP XY, D20, TP53, IGH/BCL2, TEL/AML1, RB1, MLL, 1p36/1q25, CSF1R, all Abbott® Products) at initial screening, every 12 months during follow-up and in case of suspected disease progression and a “Standardpanel” (EGR1, D7/CEP7, CEP8, TP53, D20, TEL/AML1, CEP XY, plus -if necessary- another informative probe) every 2 months in the 1^st and every 3 months in the 2^nd and 3^rd year. If bm aspirate was available, additional CCB and FISH analysis of CD34+ and native bm cells were performed. Cut-off values for each FISH probe were evaluated in our lab. Cytogenetics, bm morphology, clinical course and therapies were documented in a database. All pts gave their written informed consent. The study was approved by all local ethic committees.

After 3 years of study time, 361 patients (25 AZALE (University of Dresden), 110 LEMON5 (University of Duesseldorf), 226 CD34+FISH) have been included in the study, resulting in a total number of 19,516 FISH analyses: Median age, gender distribution and MDS subtypes were typical for the disease, median follow-up at the time of analysis was 8.2 (1–36) months. Chromosomal aberrations could be detected by FISH of CD34+ pb cells in 71.5% of pts (55% of CD34+FISH-cohort, 99% of LEMON5-trial pts, 100% of AZALE-trial pts). FISH and CCB were highly correlated: p<0.01 for CD34+ pb FISH vs CCB and p<0.01 for CD34+ bm vs CCB. The clone sizes were significantly larger in CD34+ cells compared to native pb (p<0.01).

Our interim results demonstrate that FISH analysis of circulating CD34+ pb cells provides relevant cytogenetic informations. It is a reliable novel method for screening and cytogenetic monitoring of MDS pts during the course of disease and under different therapies, and helps in cases where a bm biopsy is not possible or not successful.

Braulke:Celgene: This study was supported by Celgene. Other. Götze:Celgene: Honoraria, Membership on an entity's Board of Directors or advisory committees. Bug:Celgene: Honoraria, travel support, advisory board Other; Novartis: Honoraria, travel support, advisory board, travel support, advisory board Other; Boehringer Ingelheim: Honoraria, travel support, advisory board, travel support, advisory board Other. Schafhausen:Novartis: Honoraria, travel support Other; BMS: Honoraria, travel support, travel support Other; Roche: Honoraria, travel support, travel support Other; Celgene: Honoraria, travel support, travel support Other; Alexion: Honoraria, travel support Other. Haase:Celgene: Honoraria, Membership on an entity's Board of Directors or advisory committees.