Defining Acute Myeloid Leukemia Ontogeny in Older Patients

Acute myeloid leukemia (AML) in elderly patients is associated with poor outcomes and often arises from antecedent hematologic disorders (AHD), classified as secondary AML (sAML).

To validate the use of somatic mutations to determine AML ontogeny in the elderly population, we identified 178 elderly (> 70 years) patients with AML with NexGen Sequencing data. Patients were divided clinically into primary AML (pAML) or sAML based on prior history of AHD. Patients were then reclassified into 4 groups based on somatic mutations and cytogenetics as suggested by Lindsley et al: group 1 (pAML) with CBF rearrangements, 11q23/MLL, and NPM1 mutation (MT); group 2 (sAML) with SRSF2, SF3B1, U2AF1, ZRSR2, ASXL1, EZH2, BCOR, or STAG2 MT; group 3 with TP53 MT; and group 4 as not otherwise specified (NOS).

Based on clinical criteria, 95 patients were classified as pAML and 82 patients as sAML. Based on the AML ontogeny proposed, 8 patients were classified as pAML, 72 patients as sAML, 28 patients had TP53 MT, and 70 patients were classified as NOS. The median overall survival was 22.4,14, 2.8, and 11.2 months, respectively. Clinical versus molecular classification was discordant where 25% (n = 2) of patients classified as pAML by molecular signature had a history of AHD, whereas 44% (n = 32) of patients classified molecularly as sAML had no prior AHD. In the TP53 MT and NOS categories, 37% (n = 28) and 43% (n = 70) of patients had AHD, respectively.

Our data shows that molecular annotation of elderly patients with AML reclassifies a significant proportion of patients as sAML, which may have therapeutic implications.