CD105 (endoglin) is highly overexpressed in a subset of cases of acute myeloid leukemias.

Objectives: To assess CD105 (endoglin) expression in 119 acute myeloid leukemia (AML) and 13 control cases using immunohistochemistry.

Methods: CD105 expression was assessed retrospectively by using immunohistochemistry in bone marrow specimens.

Results: CD105 was strongly and diffusely positive in all 9 (100%) AMLs with t(15;17)(q24.1;q21.2), 2 (100%) AMLs with t(8;21)(q22;q22), 1 (100%) AML with t(6;9)(p23;q34), 7 (28%) of 25 AMLs with myelodysplasia-related changes, 1 (33%) of 3 therapy-related AMLs, 3 (16%) of 19 AMLs unclassifiable, 1 (14%) of 7 AMLs with inv(16)(p13.1q22), and 5 (11%) of 45 AMLs not otherwise specified. Uninvolved bone marrow in these cases showed no CD105 expression by erythroid precursors, megakaryocytes, or endothelial or stromal cells. Two of 13 control bone marrow specimens showed partial CD105 positivity in myeloid cells. In 21 strongly CD105+ AML cases tested for the IDH2 mutation, 9 (42%) were mutated (P = .004).

Conclusions: These data suggest that CD105 could be a therapeutic target in a subset of patients with AML.