Discovery of the First Highly Selective and Broadly Effective Macrocycle-Based Type II TRK Inhibitors that Overcome Clinically Acquired Resistance

Tropomyosin receptor kinase (TRK) secondary mutations mediating acquired resistance, especially at the solvent-front (SF) and the DFG motif, represent an unmet clinical need. Small-molecule macrocyclic kinase inhibitors have displayed significant advantages in overcoming clinical resistance driven by kinase mutations; however, all reported small-molecule macrocyclic TRK inhibitors are all type I inhibitors and are therefore much more sensitive to SF than xDFG mutations. Novel therapeutics for patients with xDFG resistance mutations are urgently needed. We report the first highly selective macrocycle-based potent type II TRK inhibitor, 7b, that exhibits high inhibitory potency toward various TRK fusion protein variants as well as wild type. 7b exhibited potent antiproliferative activity against Ba/F3 cells harboring CD74-TRKA^G667C and ETV6-TRKC^G696C with half-maximum inhibitory concentration (IC₅₀) values of 6 and 1.7 nM, respectively. More importantly, 7b also showed potent antiproliferative activity against a panel of SF mutants (IC₅₀ = 5.6-110 nM) and displayed extraordinary kinome selectivity.