Discovery of orally bioavailable ALK PROTACs based ceritinib against ALK positive cancers

Anaplastic lymphoma kinase (ALK) fusion genes promote a variety of human malignancies. Although several ALK inhibitors have significantly improved disease prognosis in patients with ALK positive cancers, the persistent emergence of acquired drug-resistant mutations remain the major problem in clinic treatment. Adoption of new therapeutic strategies such as proteolysis targeting chimera (PROTAC) to overcome drug resistance in BTK/AR-related cancers have shown promising prospect. Herein, we reported the integrate ALK PROTACs through overall optimization of linker, revealed that subtle structural differences can lead to significant activity difference, indicating the key role of conformation of PROTACs in inducing the formation of E3-PROTAC-target protein ternary complexes. A series of rigid ALK PROTACs were developed through conjugation of Ceritinib and thalidomide, orally bioavailable PROTAC 4B (F = 14.22 %) was obtained by overall optimization of molecular properties. 4B effectively induced long lasting degradation of ALK fusion proteins and strong repression of downstream pathway in Karpas 299 cells (DC