AVALIAÇÃO DE DOENÇA RESIDUAL MÍNIMA EM PACIENTES COM LEUCEMIA MIELÓIDE CRÔNICA

Abstract

Monitoring of minimal residual disease (MRD) in patients with Chronic Myeloid Leukemia (CML) who receive treatment with Imatib mesylate (IM) is extremely important, because it enables the evaluation of the response to the treatment and the early diagnosis of possible recurrences. The objective of this study was to standardize molecular methods used in order to monitor MRD in patients with CML, on therapy with IM. Peripheral blood samples were collected from 11 patients diagnosed with CML in October 2012 to September 2013, in the Department of Hematology of Hospital Araújo Jorge of the Association to Combat Cancer in Goiás. Three months after starting treatment, patients underwent a new peripheral blood collection for evaluation of MRD. Detecting bcr-abl transcripts and endogenous controls (abl and β2m) employed reverse transcription methods associated with polymerase chain reaction (RT-PCR), while quantification of bcr-abl transcripts was achieved by using reverse transcription associated with real-time PCR (RQ-PCR) and Taqman probes. Specific oligonucleotides and probes recognizing e13a2 and e14a2 junctions of bcr-abl transcripts and to the abl endogenous control were used in this study. By the time of diagnosis, three patients (27.3%) expressed the b2a2 transcript, five patients (45.5%) expressed the b3a2 transcript, two patients (18.2%) expressed both transcripts and one patient (9%) did not express any of the transcripts. The endogenous controls analysis resulted in better amplification for the abl transcript, which was used in the RQ-PCR reactions. The assessment of DRM was possible in only eight patients, due to the loss of follow-up. Three months after starting treatment with IM, all patients presented complete hematologic response. However, only one patient (12.5%) presented the undetectable transcript, reaching the full molecular response, while the other seven patients (87.95%) presented MRD. One (12.5%) of the seven patients who presented MRD, reached complete molecular response, while six patients (75%) presented a reduction of two logs, achieving minor molecular response, and one patient (12.5%) presented only partial molecular response. By using molecular biology methods, our results have enabled the standardization and the establishment of a laboratory routine, according to the international guidelines, for monitoring MRD in patients with CML.