Effect of PROTAC YX-2-107 on peripheral blood leukemia burden of NSG mice injected with a TKI-resistant Ph⁺ ALL. NSG mice were injected with a primary, human, TKI-resistant (BCR-ABL1T315I) Ph⁺ ALL sample (#557). (A-D) Peripheral blood leukemia burden was analyzed at week 7 following cell injection (pre), and after 12 and 20 days of treatment with palbociclib (mixed in the diet to achieve a dose of 150 mg/kg per day) or YX-2-107 intraperitoneally (in a Kolliphor/PBS/DMSO 20:70:10 suspension, twice daily at either 25 mg/kg or 50 mg/kg). (E-F) Fold changes of the percentages shown above.