The role of neuronal apoptosis inhibitory protein (NAIP) in acute myeloid leukemia patients

Acute myeloid leukemia (AML) is a heterogeneous, highly malignant neoplasm. Apoptosis is a complex process executed by caspases and suppressed by the inhibitor of apoptosis (IAP) family. Neuronal apoptosis inhibitory protein (NAIP), IAP’s member, may play an exceptional role in the mechanisms of tumors’ resistance to chemotherapy. The aims of the study were to assess the expression of NAIP in leukemic blasts of AML patients using flow cytometry and to evaluate its influence on disease outcome. NAIP expression was found in 106 out of 108 patients. A higher complete response rate was associated with a low expression of NAIP, age < 60 yo, and white blood cell count < 20 G/L (p = 0.009, p = 0.033, and p = 0.076, respectively) in univariate analyses and a low NAIP expression and age < 60 yo (p = 0.025 and p = 0.013, respectively) in multivariate analyses. Longer overall survival (OS) in the univariate analysis was influenced by a low NAIP expression, age < 60 yo, and intensive chemotherapy (p = 0.033, p < 0.001, and p < 0.001, respectively). In the intensively treated group, better OS was observed in patients with age < 60 yo, de novo AML, and a low NAIP expression (p = 0.03, p = 0.024, and p = 0.07, respectively). In multivariate analysis, longer OS was associated with age < 60 yo (p = 0.009) and de novo AML (p = 0.007). In conclusion, we suggest that NAIP might play an adverse role in response to chemotherapy.