The aggressiveness of PI3K-altered T-ALL is deeply imprinted in the blasts, as patient-derived xenografts (PDX) generated from fresh primary samples recapitulated their clinical characteristics marked by higher engraftment rates (Fig. 1C), and a rapid expansion in mice compared to wild-type cases (Fig. 1D, E). This evidence concerns the gene PIK3CA and acute lymphoblastic leukemia.