Clonal Evolution of Preleukemic Hematopoietic Stem Cells Precedes Human Acute Myeloid Leukemia

Abstract

Given that most bone marrow cells are short-lived, the accumulation of multiple leukemogenic mutations in a single clonal lineage has been difficult to explain. Here, we propose that serial acquisition of mutations occurs in self-renewing hematopoietic stem cells (HSCs). We investigated this model through genomic analysis of HSCs from six patients with de novo acute myeloid leukemia (AML). Using exome sequencing, we identified mutations present in individual AML patients harboring the FLT3-ITD mutation. We then screened the residual HSCs and detected some of these mutations including mutations in the NPM1, TET2, and SMC1A genes. Finally, through single cell analysis, we determined that a clonal progression of multiple mutations occurred in the HSCs of some AML patients. These pre-leukemic HSCs suggest the clonal evolution of AML genomes from founder mutations, revealing a potential mechanism contributing to relapse. Such pre-leukemic HSCs may constitute a cellular reservoir that needs to be targeted therapeutically for more durable remissions.

How One Thing Led to Another

“…We formed a team (see authors in References 183,[203][204][205] to test the hypothesis in patient AMLs. We carried out exome sequencing of the AMLs to collect somatic mutations not found in patient T cells; prepared DNA primers for each DNA altered region; then isolated single HSCs, which we could expand ∼30-to 100-fold without losing the mutations; and then tested each normal HSC clone for the mutations (204,205).…”

“…We formed a team (see authors in References 183,[203][204][205] to test the hypothesis in patient AMLs. We carried out exome sequencing of the AMLs to collect somatic mutations not found in patient T cells; prepared DNA primers for each DNA altered region; then isolated single HSCs, which we could expand ∼30-to 100-fold without losing the mutations; and then tested each normal HSC clone for the mutations (204,205). All 21 AMLs analyzed could be shown to have the entire preleukemic progression in cells of HSC phenotype, and in all tested AMLs, the LSCs came out at the MPP or slightly more differentiated LGMP (lymphoid, granulocytic, monocytic progenitor) cells (204,205).…”

Persistence of pre-leukemic clones during first remission and risk of relapse in acute myeloid leukemia

“…1 Sequential acquisition of somatic mutations in AML driver genes can result in pre-leukemic HSCs capable of increased proliferation or selfrenewal, but retaining normal multi-lineage differentiation potential. In some AML patients, preleukemic HSCs carrying early disease-associated "founder" mutations can be identified besides the fully transformed leukemia clone.…”

“…In some AML patients, preleukemic HSCs carrying early disease-associated "founder" mutations can be identified besides the fully transformed leukemia clone. 1,2 Mutations in pre-leukemic HSCs frequently affect genes also implicated in age-associated clonal hematopoiesis, such as DNMT3A and TET2. Preleukemic clones may survive chemotherapy and persist in AML patients during complete remission (CR).…”

Guest editorial: Connecting multiple aspects of hematologic malignancies toward creation of new therapeutics

“…The existence of pre-leukemic stem cells is another groundbreaking discovery, reported more recently [2][3][4]. In the pre-leukemic stem cell model, it is thought that multiple somatic mutations hit immature hematopoietic stem and progenitor cells and incite genetic events that ultimately lead to leukemogenic transformation.…”