Background: Three types of PML-RARα mRNA fusion transcripts in acute promyelocytic leukemia (APL) could be existed: a short (S)-form type, a long (L)-form type or a variable (V)-form type. Whether 3 types of PML-RARα mRNA fusion transcripts associated with different manifestations and outcomes in individual APL cases are unclear. Recently, some studies reported the controversial results for the relationship between the types of PML-RARα mRNA fusion transcripts and clinical outcomes. But, there was no data about the types of PML-RARα mRNA fusion transcripts especially for the APL patients who were received remission induction therapy with AIDA.

Methods: We performed a retrospective analysis for the data of 94 patients with APL, whose isoform data was available. We evaluated the differences of therapeutic outcome of remission induction chemotherapy in terms of response rate, relapse-free survival (RFS), overall survival (OS) and the association of pretreatment clinical parameter characteristics according to the PML-RARα isoforms.

Results: The median age of the patients was 41 years (15–85). CR rate following remission induction treatment was 84.9% (AIDA 87.0% vs. non-AIDA 80.0%). Among 94 patients, there were 58 L-form cases (62.1%), 32 S-form cases (34.0%), 4 V-form cases (4.3%). There was no significant difference at any patient’s pretreatment characteristic according to PML-RARα isoform type. CR rate was higher in the group of initial WBC <10,000/ul (93.5% vs. 65.4%, p=0.001). But there was no difference within the isoform L/S subgroup (84.2% vs. 87.2%). And OS and RFS were not different between isoform L/S subgroup (5yr 74.3% vs. 83.1%, 84.2% vs. 85.1%). AIDA induction group was better than non-AIDA induction group regarding OS and RFS (5yr 84.4% vs 55.7%, p=0.026, 90.0% vs 65.7%, p=0.007), but not significant in the multivariate analysis. And also, it was not significantly different in the OS and RFS between isoform L/S subgroup of the AIDA induction group (5yr 80.5% vs. 92.0%, 95.7% vs. 97.0%).

Conclusion: This study suggests that

  1. high initial WBC count is associated with low CR rate,

  2. AIDA induction group has a trend of better OS and RFS,

  3. treatment outcomes according to PML-RARα isoform type are not different.

Prospective study will be needed to confirm the meaningful significance of PML-RARα isoform type.

Topics:
acute promyelocytic leukemia, progressive multifocal leukoencephalopathy, protein isoforms, rna, messenger, remission induction, chemotherapy regimen, leukocyte count, treatment outcome, l-form bacteria

Author notes

Disclosure: No relevant conflicts of interest to declare.

2007, The American Society of Hematology
2007
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