Discovery of CH7057288 as an Orally Bioavailable, Selective, and Potent pan-TRK Inhibitor

Selective type II TRK inhibitors overcome xDFG mutation mediated acquired resistance to the second-generation inhibitors selitrectinib and repotrectinib

Neurotrophic receptor kinase (NTRK) fusions are actionable oncogenic drivers of multiple pediatric and adult solid tumors, and tropomyosin receptor kinase (TRK) has been considered as an attractive therapeutic target for "pan-cancer" harboring these fusions. Currently, two generations TRK inhibitors have been developed. The representative second-generation inhibitors selitrectinib and repotrectinib were designed to overcome clinic acquired resistance of the first-generation inhibitors larotrectinib or entrectinib resulted from solvent-front and gatekeeper on-target mutations. However, xDFG (TRKAG667C/A/S, homologous TRKCG696C/A/S) and some double mutations still confer resistance to selitrectinib and repotrectinib, and overcoming these resistances represents a major unmet clinical need. In this review, we summarize the acquired resistance mechanism of the first- and second-generation TRK inhibitors, and firstly put forward the emerging selective type II TRK inhibitors to overcome xDFG mutations mediated resistance. Additionally, we concluded our perspectives on new challenges and future directions in this field.

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, TRKAG595R, TRKAG667C, and TRKAF589L 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-NTRK1G595R and BaF3-CD74-NTRK1G667C xenograft models. The study provides a promising lead compound for pan-anticancer drug discovery.

Recent advances in the discovery of tropomyosin receptor kinases TRKs inhibitors: A mini review

The tropomyosin receptor tyrosine kinases (TRKs) control the cell proliferation mainly in the nervous system and are encoded by NTRK genes. Fusion and mutation of NTRK genes were detected in various types of cancers. Many small molecules TRK inhibitors have been discovered during the last two decades and some of them have entered clinical trials. Moreover, two of these inhibitors; larotrectinib and entrectinib; were approved by FDA for the treatment of TRK-fusion positive solid tumors. However, mutation of TRK enzymes resulted in resistance to both drugs. Therefore, next generation TRK inhibitors were discovered to overcome the acquired drug resistance. Additionally, the off-target and on-target adverse effects on the brain initiated the need for selective TRK subtype inhibitors. Indeed, some molecules were recently reported as selective TRKA or TRKC inhibitors with minimal CNS side effects. The current review highlighted the efforts done during the last three years in the design and discovery of novel TRK inhibitors.