Structure-Based Optimization of the Third Generation Type II Macrocycle TRK Inhibitors with Improved Activity against Solvent-Front, xDFG, and Gatekeeper Mutations

The solvent-front (SF), gatekeeper, and xDFG motif mutations of tropomyosin receptor kinase (TRK) mediating acquired resistance of larotrectinib and entrectinib represent an unmet clinical need. To date, no effective drugs are being approved to overcome these mutants. Thus, a series of macrocycle compounds were designed and synthesized as new type II TRK inhibitors to combat clinically relevant mutations. The representative compound 10g exhibited excellent potency against wide type TRKA/C, TRKA^G595R, TRKA^G667C_, and TRKA^F589L with IC₅₀ values of 5.21, 4.51, 6.77, 1.42, and 6.13 nM, respectively, and a good kinome selectivity against 378 kinases. 10g also strongly suppressed the proliferation of Ba/F3 cells transfected with SF, GK, xDFG, and others (Val to Met) single mutants with IC₅₀ values of 1.43-47.56 nM. Moreover, 10g demonstrated ideal antitumor efficacy in both BaF3-CD74-NTRK1^G595R and BaF3-CD74-NTRK1^G667C xenograft models. The study provides a promising lead compound for pan-anticancer drug discovery.