The clinical impact of microRNA-99a in AML patients undergoing allo-HSCT – a Chinese study

Recent studies have shown that microRNA-99a (miR-99a) is upregulated on leukemia stem cells and is associated with poor prognosis in acute myeloid leukemia (AML) patients.¹ However, the clinical significance of miR-99a and its predictive value in AML patients undergoing post-allogeneic hematopoietic stem cell transplantation (allo-HSCT) has not been evaluated yet.²

Zhiheng Cheng from Huaihe Hospital of Henan University, Kaifeng, China, and colleagues retrospectively analyzed 74 de novo AML patients with miR-99a expression who underwent allo-HSCT. Data was collected from The Cancer Genome Atlas database. Median follow-up time was 29 months. Their findings were published ahead of print in Bone Marrow Transplantation on 7 March 2018.

Patients were divided into two groups based on their miR-99a expression levels:

• miR-99a^high group (miR-99a levels were above or equal to median expression level): n = 37, median age = 51 years (range, 22–65)
• miR-99a^low group (miR-99a levels were lower than median expression level): n = 37, median age = 51 years (range, 18–72)

Key findings:

• Survival in all patients

  • Median event-free survival (EFS): 12.8 (range, 1.9–106.9) months
  • Median overall survival (OS): 29 (range, 6.6–128.5) months
• Patients in the miR-99a^high group had significantly shorter EFS (P = 0.026) and OS (P = 0.010) than the miR-99a^low group
  • High miR-99a expression associated with inferior EFS: HR = 1.834 (95% CI, 1.056–3.160), P = 0.029
  • High miR-99a expression associated with inferior OS: HR = 2.012 (95% CI, 1.167–3.467), P = 0.012
• High miR-99a expression was an independent risk factor for EFS: HR = 1.909 (95% CI, 1.043–3.494), P = 0.036
• High miR-99a expression was an independent risk factor for OS: HR = 2.179, (95% CI, 1.192–3.982), P = 0.011

In summary, these results showed that high miR-99a expression may be an efficient marker to predict inferior outcomes in AML patients undergoing allo-HSCT. The authors further added that their findings indicated that “allo-HSCT could not overcome the adverse prognostic effect of miR-99a.” Further studies are required to validate these results.