Organoids-based high-throughput drug screening identifies selective vulnerability of AR -/lo CRPC to inhibitors of neurotransmission signaling

Introduction of the next generation of potent antiandrogens (abiraterone, enzalutamide, apalutamide, darolutamide) about a decade ago into the clinical management of advanced prostate cancer (PCa) patients has led to a substantial increase in a subtype of castration-resistant PCa (CRPC) that becomes independent of androgen receptor (AR) signaling and frequently lacks AR expression (i.e., AR -/lo ). The AR -/lo CRPC is de novo resistant to castration and enzalutamide (Enza), and there are currently no targeted therapies available for this subtype. To identify novel regulators and therapeutic targets in AR -/lo CRPC, we developed an organoids platform from the AR -/lo LAPC9-AI (androgen-independent, i.e., CRPC) xenograft model (Li and Deng et al., Nat. Commun . 2018) that recapitulates the AR -/lo CRPC phenotype and drug responsiveness. Using this platform, we conducted high-throughput screening (HTS) in a total of ~6,000 compounds and drugs (including 4,480 bioactive agents and 1,508 FDA-approved drugs). Secondary screening and validation experiments, surprisingly, uncovered 21 compounds effective in inhibiting the AR -/lo CRPC organoids, including JTC-801, Penfluridol and Terfenadine, which normally target the G protein-coupled receptors activated by neurotransmitters including dopamine receptor and opioid receptor. Notably, JTC-801 and Penfluridol specifically inhibited the growth of AR -/lo LAPC9-AI in vivo . Collectively, our study identifies novel therapeutic vulnerabilities in castration/Enza-resistant AR -/lo CRPC.