Entrectinib

Target: Entrectinib targets TRKA/B/C, ROS1, and ALK kinase proteins in multikinase profiling studies.

Mechanism of Action: Entrectinib can function as a multikinase target-recognition ligand for PROTACs directed toward TRK, ROS1, or ALK proteins. The ligand portion binds the selected kinase domain, whereas the linker and E3 ligase ligand recruit ubiquitin-ligase machinery. Because entrectinib has multiple validated kinase targets, degrader selectivity must be established experimentally by ternary-complex formation and cellular degradation profiles. A productive complex can drive ubiquitination of the engaged kinase, leading to proteasome-dependent degradation of that protein. This establishes a testable protein-depletion mechanism for research assays.

• PROTAC Ligand for TRK: Entrectinib can be used as a targeting moiety in PROTAC designs to recruit TRK family kinases (TRKA/B/C) to E3 ligases. This enables systematic evaluation of whether ternary complex formation and ubiquitination drive efficient TRK degradation, supporting mechanistic studies of kinase removal versus inhibition.

• PROTACs for ROS1 Degradation: As a ROS1-directed small-molecule binder, Entrectinib may serve in PROTAC constructs aimed at ROS1 degradation. Researchers can optimize linker length and attachment sites to promote stable ternary complexes, quantify ubiquitination, and measure degradation kinetics, thereby clarifying how PROTAC-mediated ROS1 loss affects downstream signaling and cellular phenotypes.

• PROTACs for ALK Targeting: Entrectinib can be incorporated into PROTAC platforms to explore ALK-directed targeted protein degradation. By engineering Entrectinib-based chimeras with different E3 ligase recruiters, investigators can compare degradation potency across ALK variants, assess resistance-associated effects, and map structure–degradation relationships that distinguish degradation from mere kinase blockade.

• Mechanistic Studies of Kinase Removal: Entrectinib-based PROTACs support rigorous studies on the determinants of targeted degradation, including ternary complex stability, E3 ligase engagement, and proteasome dependence. Using phospho-proteomics and time-resolved viability assays, researchers can correlate degradation depth with pathway shutdown, enabling selection of optimal chimeric architectures for TRK/ROS1/ALK contexts.

Entrectinib is a multi-kinase ligand for TRK family kinases, ROS1, and ALK, providing a broad receptor-kinase warhead for chemical-biology studies. Its indazole, benzamide, morpholinyl/piperazinyl, and oxanyl motifs create multiple possible positions for PROTAC-oriented derivatization. This molecule is described in detail below.

Structure: The molecule contains an indazole benzamide core bearing a difluorobenzyl substituent, a 4-methylpiperazinyl group, and an oxan-4-ylamino substituent. These heteroatom-rich features combine hinge-binding potential, polar solubilization, and three-dimensional side-chain character.

Reactivity: For TRK/ROS1/ALK degrader design, linker growth should be guided by co-structure or SAR data and may be explored from the piperazine or oxanyl amino periphery while preserving the indazole-benzamide kinase-recognition motif. PEG, alkyl, or triazole-containing linkers can be combined with CRBN or VHL ligands; because the parent ligand is multi-targeted, degradation selectivity should be evaluated across relevant kinase panels.