In vivo responses to PR-104 of T-ALL and BCP-ALL engrafted mice. NOD/SCID mice were engrafted with a T-ALL, ALL-27 (A) or a BCP-ALL, ALL-19 (B) patient-derived xenograft. When the proportion of hCD45⁺ cells in the PB reached 1%, the mice were treated with PR-104 at 200 mg/kg weekly for 2 weeks (red), and compared with vehicle-treated control (black). When the proportion of hCD45 reached 25% in the PB, mice were scored as event on the corresponding Kaplan-Meier curves on the right panel. (C) LGD is plotted for the BCP-ALL and T-ALL xenografts. PR-104 showed a significantly greater efficacy in T-ALL than BCP-ALL xenografts (Fisher exact test, P = .03). (D) COMPARE-like plots show the objective response measures (ORMs) for 4 T-ALL (ALL-8, ALL-27, ALL-29, and ALL-31) (black) and 3 BCP-ALL (ALL-2, ALL-4, and ALL-19) (gray) xenografts. Responses represent the difference in xenograft objective response from the midpoint (0) representative of stable disease (SD). Bars to the right indicate an objective response (PR, CR, and MCR), whereas those to the left indicate PD. Data for the complete panel of xenografts are available in Table 2 and supplemental Figure 1.