ABSTRACT
BACKGROUND/AIMS: There are three types of PML-RAR alpha mRNA fusion transcripts associated with acute promyelocytic leukemia (APL): the short (S)-form, the long (L)-form and the variable (V)-form. No study on the Korean population has addressed the clinical significance of the specific types of PML-RAR alpha mRNA fusion transcripts for APL patients who receive the combination therapy of all-trans-retinoic-acid and idarubicin (AIDA regimen). METHODS: We performed a retrospective analysis on 94 patients with APL to evaluate differences in the therapeutic outcomes, such as the response rate, an event-free survival (EFS), and overall survival (OS), after remission following the induction of chemotherapy. We also analyzed whether differences in the pretreatment clinical characteristics depend on the PML-RAR alpha isoform. RESULTS: The median age of the patients was 41 years (range 15-85). Among the 94 patients, there were 58 L-form cases (62.1%), 32 S-form cases (34.0%), and 4 V-form cases (4.3%). The CR rate following remission induction treatment was 84.9%. The CR rate was higher in patients with an initial WBC <10.0x109/L, as compared to patients with an initial WBC higher than 10.0X109/L (93.5% vs. 65.4%, p=0.001). The AIDA induction regimen was associated with a better EFS than non-AIDA induction regimens (81.9% vs. 49.6%, p=0.006). The induction group was also a significant prognostic factor for EFS in the multivariate analysis (p=0.020). There were no differences in OS and EFS in patients with either isoform L or isoform S in the AIDA induction group. CONCLUSIONS: This retrospective study demonstrated that pretreatment clinical characteristics and treatment outcomes were not significantly different among patients with varying PML-RAR alpha isoform types in the AIDA induction group.