Figure 1.
Constitutive activation of PI3K pathway signaling in children with relapsed/refractory acute lymphoblastic leukemia enrolled on TACL2014-001. Pre-treatment (basal, day 0) peripheral blood samples were obtained from study patients with acute lymphoblastic leukemia (ALL) for single-cell phosphoflow cytometry analysis of the PI3K pathway and other phosphoproteins as previously described.15 Pre-treatment blood specimens from most patients show basal activation of multiple PI3K/mTOR pathway phosphoproteins in gated human leukemia cells (CD45+/CD19+ B-ALL or CD45+/CD3+ for T-ALL) when compared to fluorescence-minus-one (FMO)-stained control cells. Solid symbols represent patients with partial response, stable disease, or progressive disease after cycle 1. Black-ringed symbols represent patients with complete response.