Fig. 3 Asciminib resistance hotspots in ABL1 regulatory domains

Figure 3 details the deep mutational scanning (DMS) results that map asciminib resistance hotspots within the regulatory SH3, SH2, and linker domains. The data demonstrates that mutations in the SH2-kinase linker (particularly at P230) and the SH3 domain's RT loop disrupt the autoinhibitory SH3-linker interaction, driving potent resistance to the drug. Within the SH2 domain, the canonical phosphotyrosine-binding residues (such as R152) are shown to be dispensable for resistance. Instead, resistance centers around a critical tripartite interaction involving Y139, Y342, and H375 at the SH2-kinase interface. Mutations at these sites likely break the allosteric clamping mechanism required for asciminib to function. Finally, the figure's functional validation assays confirm that several of these novel regulatory domain mutations are capable of sustaining high-level cellular resistance even at extreme asciminib concentrations of up to 1000 nM.