Role of RT-PCR and FISH in diagnosis and monitoring of acute promyelocytic leukemia.

Background: Patients with a presence of Promyelocytic Leukemia-Retinoic Acid Receptor Alpha (PML-RARA) genes rearrangement predict a favorable response to all-trans retinoic acid (ATRA), and a significant improvement in survival. Therefore, establishing the presence of PML-RARA rearrangement is important for optimal patient management. Aim: The objective of this study is to compare and assess the role of fluorescent in situ hybridization (FISH) and reverse transcriptase polymerase chain reaction (RT-PCR) in the diagnosis and long-term monitoring of Acute Promyelocytic Leukemia (APL). Materials and Methods: We compared 145 samples received at different interval of times to analyze the sensitivity of RT-PCR and FISH. Results: The failure rate for RT-PCR was 4% at baseline, 13% at induction, and 0% at the end of consolidation. And for FISH it was 8% at baseline, 38% at induction, and 66% at the end of consolidation. The predictive values of relapse in the patients who were positive and negative by RT-PCR, at the end of induction, were 60 % and 3%, respectively, and at end of consolidation it was 67 % and 4%, respectively. On the other hand the predictive values of relapse in patients who were positive and negative by FISH at end of induction were 57 % and 6%, respectively; while at end of consolidation it was 14% who were negative by FISH. Conclusion: Both RT-PCR and FISH are important for the diagnosis of APL cases, as both techniques complement each other in the absence or failure of any one of them. However, RT-PCR is more sensitive than FISH for the detection of minimal residual disease in the long-term monitoring of these patients. The present study shows that the predictive value of relapse is more associated with minimal residual disease (MRD) results by RT-PCR than that by FISH.

Imatinib mesylate in chronic myeloid leukemia: a prospective, single arm, non-randomized study.

Chronic myeloid leukemia (CML) is a hematopoietic stem cell disorder characterized by the balanced reciprocal translocation t (9:22). The resulting fusion gene, the BCR-ABL, is responsible for oncogenesis. Imatinib mesylate is a novel molecule, which inhibits the protein product of this fusion gene and hence has been used in the treatment of CML. The present study evaluates 174 patients with CML treated with imatinib mesylate. Of these 174 patients, 97 were in chronic phase, 47 in accelerated phase and 30 patients had blast crisis. Patients in chronic phase received imatinib mesylate in the dose of 400-mg daily, while those in accelerated phase and blast crisis received 600 to 800 mg daily. Of the 97 patients with chronic phase, 49 patients (50.5%) achieved a major (major + complete) cytogenetic response. Of the 47 patients in accelerated phase, 10 patients (21.3%) achieved a major cytogenetic response and in 30 patients with blast crisis, 7 (23.3%) achieved a major cytogenetic response. Dermatitis, mucositis, neutropenia and thrombocytopenia were some of the major toxicities. Of interest, 121 of the 174 patients (69.5%) developed generalized hypopigmentation. We conclude that imatinib mesylate is a safe and effective first-line therapy for chronic myeloid leukemia.