No prognostic significance of normalized copy number of PML-RARA transcript at diagnosis in patients with acute promyelocytic leukemia.

BACKGROUND: Acute promyelocytic leukemia is a peculiar disease with few studies that have investigated the prognostic significance of PML/RARA transcript level at diagnosis.

PATIENTS AND METHODS: This retrospective study included all cases diagnosed with acute promyelocytic leukemia over the period from June 2015 to March 2019. The normalized copy number (NCN) was tested by real-time polymerase chain reaction at diagnosis, and at the end of induction regimen.

RESULTS: Our study included 83 de novo APL patients, 53 (63.9%) were adults and 30 (36.1%) were children. The median (range) age of our patients was 28.0 (1.0-70.0) years. The pediatric group had a significantly higher prevalence in males (p = 0.02), higher incidence of disseminated intravascular coagulopathy (p = 0.014), and high-risk groups (p = 0.017). At diagnosis, the median NCN (%) of the entire group at 22.5 was set as the cut off value. There was no significant association between NCN at diagnosis and other prognostic variables except for bone marrow promyelocytes (p = 0.006). High-risk group APL patients as well as those presenting with hemorrhage had an inferior overall survival (OS) (p = 0.007; p < 0.001) respectively. PML-RARA NCN at diagnosis did not have an impact on the OS or increased risk of relapse of our patients (p = 0.434; p = 0.721).

CONCLUSION: the initial PML/RARA tumor burden is not a prognostic factor for APL. The initial TLC at 10x109 /L cut off is the most important predictive for OS. Early detection and close monitoring are required to decrease the high rate of early deaths in developing countries.