In vivo self-assembled nano-PROTAC for the dual degradation of AR and HSP90 to overcome castration-resistant prostate cancer resistance

Abstract Castration-resistant prostate cancer demonstrates intrinsic or acquired resistance to second-generation androgen-targeted therapies, posing a challenge in clinical treatment. In this study, on the basis of in vivo self-assembly nanotechnology, we designed a PSMA-targeted nano-PROTAC with a proximity degradation effect. Nano-PROTAC not only precisely degrades the AR receptor but also cleverly degrades the HSP90 that is closely bound to the AR receptor, utilizing the spatial distance self-adaptive characteristics of its nanostructure. In the 22Rv1 cell model, Nano-PROTAC degraded 80% of the AR protein and 65% of the HSP90 protein. More importantly, nano-PROTAC could degrade 74% of the AR splice variant AR-V7 protein, showing the potential ability to overcome drug resistance. We further constructed an enzalutamide-resistant xenograft tumor mouse model to evaluate the therapeutic effect of the Nano-PROTAC. Compared with the combination treatment group of AR and HSP90 inhibitors (enzalutamide and pimitespib), the nano-PROTAC treatment group presented a high tumor growth inhibition value of up to 78% and a median survival extension of 15 days. Nano-PROTACs that simultaneously degrade AR and HSP90 can overcome the resistance of prostate cancer to PSMA- and AR-positive castration-resistant prostate cancer, except for neuroendocrine prostate cancer, which provides a new therapeutic strategy for the treatment of prostate cancer.