This idea hinges mainly on work in Figures 2,3 and 4. In barcoded KCL-22 cells (Figure 2b-f), clones that grow with ABL001 are not the ones that grow with nilotinib, so each drug leaves a different resistance pool. KCL-22 xenografts on single-agent ABL001 or nilotinib show an early drop in tumor size and then a return of growth with resistance (Figure 3a). With the ABL001-nilotinib pair from the start (Figure 3b), tumor size falls and does not return after treatment stops. In one CML patient, ABL001 gives a clear response and later the disease comes back with myristoyl-pocket mutations, the same kind of resistance as in the preclinical work (Figure 4).