Figure 3.
Figure 3. Clinical response to mIDH2 inhibition is associated with induction of myeloid differentiation. (A) Representative immunophenotypic analyses by flow cytometry on sequential bone marrow samples. Cell-surface markers studied are shown. Data from a responding patient (pretreatment to CR to relapse) (left). Data from a nonresponding patient (pretreatment to progressive disease) who remained in stable disease during treatment (right). Numbers in FACS plots refer to the size of the population as a percentage of lineage-negative bone marrow mononuclear cells. For normal bone marrow (n = 12), the standard deviation is ±2.7% for immature progenitor, ±9.6% for immature precursors, and ±9.7% for mature myeloid cells. (B) Graph showing ratio of immature to mature cell populations by flow cytometry from bone marrow over time (top): the average ratios of myeloid progenitor or myeloid precursors to mature myeloid cells in bone marrow from normal donors (n = 12) and 5 patients who had either a CR or a PR with enasidenib are shown. In patient 201-010, the changing size of myeloid precursor (red) cell populations in relation to mature myeloid cells is shown. In the remaining 3 patients, the changing size of myeloid progenitor (blue) populations to mature cells is shown. Colored bars represent the 95% confidence intervals in normal controls. The mIDH2 VAF in each patient at different time points in all bone marrow mononuclear cells (VAF total) and in FACS-sorted mature myeloid cells (CD34−CD117−) are shown (bottom). (C) mIDH2 VAF in bone marrow mononuclear cells prior to treatment (blue) and in sorted peripheral blood neutrophils at time of best response (red) in 7 patients achieving CR (top). VAF of indicated mutation in bone marrow mononuclear cells prior to treatment and in sorted peripheral blood neutrophils at time of best response in 2 patients achieving CR (middle and bottom). (D) Histogram of the percentages of functional neutrophils observed in ex vivo enasidenib-treated patient samples (left) and representative images (right) assessed by phagocytic assay quantifying neutrophils (blue) that contained latex beads (green). The percentage of neutrophils containing beads was measured by scoring 5 different fields of view per sample. BRCA2, breast cancer type 2; Gran, granulocyte; PD, progressive disease; Post, time of best response; Pre, prior to treatment; TNC, total nucleated cell count.

Clinical response to mIDH2 inhibition is associated with induction of myeloid differentiation. (A) Representative immunophenotypic analyses by flow cytometry on sequential bone marrow samples. Cell-surface markers studied are shown. Data from a responding patient (pretreatment to CR to relapse) (left). Data from a nonresponding patient (pretreatment to progressive disease) who remained in stable disease during treatment (right). Numbers in FACS plots refer to the size of the population as a percentage of lineage-negative bone marrow mononuclear cells. For normal bone marrow (n = 12), the standard deviation is ±2.7% for immature progenitor, ±9.6% for immature precursors, and ±9.7% for mature myeloid cells. (B) Graph showing ratio of immature to mature cell populations by flow cytometry from bone marrow over time (top): the average ratios of myeloid progenitor or myeloid precursors to mature myeloid cells in bone marrow from normal donors (n = 12) and 5 patients who had either a CR or a PR with enasidenib are shown. In patient 201-010, the changing size of myeloid precursor (red) cell populations in relation to mature myeloid cells is shown. In the remaining 3 patients, the changing size of myeloid progenitor (blue) populations to mature cells is shown. Colored bars represent the 95% confidence intervals in normal controls. The mIDH2 VAF in each patient at different time points in all bone marrow mononuclear cells (VAF total) and in FACS-sorted mature myeloid cells (CD34CD117) are shown (bottom). (C) mIDH2 VAF in bone marrow mononuclear cells prior to treatment (blue) and in sorted peripheral blood neutrophils at time of best response (red) in 7 patients achieving CR (top). VAF of indicated mutation in bone marrow mononuclear cells prior to treatment and in sorted peripheral blood neutrophils at time of best response in 2 patients achieving CR (middle and bottom). (D) Histogram of the percentages of functional neutrophils observed in ex vivo enasidenib-treated patient samples (left) and representative images (right) assessed by phagocytic assay quantifying neutrophils (blue) that contained latex beads (green). The percentage of neutrophils containing beads was measured by scoring 5 different fields of view per sample. BRCA2, breast cancer type 2; Gran, granulocyte; PD, progressive disease; Post, time of best response; Pre, prior to treatment; TNC, total nucleated cell count.

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