Pre-clinical evaluation of probes to detect t(8;21) AML minimal residual disease by fluorescence in situ hybridization

Minimal residual disease (MRD) in remission t(8;21) AML and in vivo differentiation detected by FISH and CD34+ cell sorting

“…15 This produced two fusion signals from the derivative chromosomes, as well as two discrete signals from the remaining normal alleles, resulting in a marked reduction in false positives as has been reported with other D-FISH probes. [15][16][17] With the near elimination of false positive signals in interphase cells, we have undertaken an analysis of MRD. Our results demonstrate that residual positive cells, in the range of 1-4 per 2000 (0.05-0.19%), can be identified in bone marrow from a majority of patients in hematologic and cytogenetic remission.…”

“…To overcome this problem in t(8;21) AML, we developed a probe set (D-FISH AML1/ETO) that utilized probes from each side of both translocation breakpoints. 15 This produced two fusion signals from the derivative chromosomes, as well as two discrete signals from the remaining normal alleles, resulting in a marked reduction in false positives as has been reported with other D-FISH probes. [15][16][17] With the near elimination of false positive signals in interphase cells, we have undertaken an analysis of MRD.…”

“…While single-fusion probes have false positive rates in the order of 3% due to random overlapping signals, D-FISH probes which recognize both sides of both translocation breakpoints are substantially more specific as is the case with this probe set. [15][16][17] While the clinical utility of monitoring MRD is unclear, MRD detection without quantitation is insufficient since longterm survival with positive cells has been convincingly demonstrated in t(8;21) AML. 5,7,8 This is not unique to t(8;21) AML as persistence of the PML-RAR␣ fusion transcript, resulting from the 15;17 translocation, has also been associated with long-term remission.…”

“…Slides were submitted to a dual-color, dual-target FISH assay as previously described 15 with modifications. Briefly, after the bone marrow cells were fixed and dropped on to microscope slides, they were washed for 1 min in 70% acetic acid, then dehydrated and denatured in 70% formamide/2× SSC at 72°C for 3-4 min.…”

Estudo cromossômico no sangue periférico de pacientes com diferentes tipos de leucemia do Hospital de Base, São José do Rio Preto - SP

“…Hoje, tem permitido a detecção de alterações cromossômicas como fator diagnóstico, a classificação citogenética das neoplasias hematológicas, a caracterização de diferentes estágios do desenvolvimento neoplásico, a avaliação da remissão, agudização e do prognóstico destas enfermidades e de diversos genes envolvidos nestes processos (10,11,12).…”