Comparison of clonal architecture between primary and immunodeficient mouse-engrafted acute myeloid leukemia cells

Clonal dynamics and selection have not been fully understood in patient-derived xenografts (PDX) of acute myeloid leukemia (AML). Here, the authors generate 160 AML-PDX models to track the clonal dynamics of primary and relapsed AML, and find selectively enriched subclones that are associated with resistance to therapy. Patient-derived xenografts (PDX) are widely used as human cancer models. Previous studies demonstrated clonal discordance between PDX and primary cells. However, in acute myeloid leukemia (AML)-PDX models, the significance of the clonal dynamics occurring in PDX remains unclear. By evaluating changes in the variant allele frequencies (VAF) of somatic mutations in serial samples of paired primary AML and their PDX bone marrow cells, we identify the skewing engraftment of relapsed or refractory (R/R) AML clones in 57% of PDX models generated from multiclonal AML cells at diagnosis, even if R/R clones are minor at <5% of VAF in patients. The event-free survival rate of patients whose AML cells successfully engraft in PDX models is consistently lower than that of patients with engraftment failure. We herein demonstrate that primary AML cells including potentially chemotherapy-resistant clones dominantly engraft in AML-PDX models and they enrich pre-existing treatment-resistant subclones.

Automated summary

The clonal dynamics and selection mechanisms in patient-derived xenografts (PDX) of acute myeloid leukemia (AML) are not fully understood. In this study, the authors generated 160 AML-PDX models to track the clonal dynamics of primary and relapsed AML, finding selectively enriched subclones associated with therapy resistance.