Figure 1 from FLT3/CD99 Bispecific Antibody–Based Nanoparticles for Acute Myeloid Leukemia

Interplay between CD99 and FLT3 in FLT3-ITD AML. Flow cytometry was used to evaluate the surface level expression of FLT3 and CD99. A and B, Compared to naive MV4-11 cells, midostaurin-resistant (MV4-11-R) cells have a significant increase of surface expression of FLT3 (P = 0.0356), and trend of increase of CD99 (P = 0.0568). C, To examine the effect of targeting CD99 on FLT3 surface expression, a panel of cell lines were assessed. U937 do not express FLT3 and were included as negative control. D, THP-1 cells, although they express the FLT3-WT, did not show enhance FLT3 surface level expression upon treatment with CD99-A192. E, In contrast, treatment with CD99-A192 increased FLT3 surface level expression in MOLM-13 cells, which are FLT3-ITD⁺ (P = 0.05). F, NSG mice were engrafted with 2.5 × 10⁶ MOLM-13 cells, showed a significant increase in survival when treated with both FLT3 and CD99 targeted nanoparticles P < 0.007 and P < 0.003 of combination vs. CD99-A192, FLT3-A192 alone respectively.