Cell-resolved high-dimensional imaging analysis, therapeutic modeling, and a Phase Ib clinical study validate BCL-2 as a target across heterogeneous CRPC subtypes

BCL-2 has been implicated in prostate cancer (PCa) progression and development of castration-resistant disease (CRPC); however, it remains unclear how the BCL-2- and AR-expressing PCa cell populations evolve across the PCa continuum, how AR molecularly regulates BCL-2 and whether BCL-2 represents a common therapeutic target in heterogeneous CRPC. Here we first show the selective induction of BCL-2 by AR pathway inhibitors (ARPIs). Vectra-based quantitative multiplex immunofluorescence (qmIF) and image mass cytometry (IMC) analyses with single-cell resolution in patient PCa and xenograft models reveal markedly increased BCL-2 + (AR + or AR - ) PCa cells in CRPC. Mechanistically, AR represses BCL-2 transcription through several AR binding sites and ARPIs relieve this repression. Therapeutic studies in cells, organoids and xenografts support BCL-2 as a shared vulnerability across diverse CRPC subtypes. A Phase Ib clinical trial ( NCT03751436 ) combining enzalutamide and BCL-2 inhibitor venetoclax demonstrated reduced circulating tumor cells in responding patients. By integrating high-content qmIF and IMC analyses with mechanistic studies, extensive preclinical therapeutic experiments and a Phase Ib clinical trial, our studies herein elucidate the AR +/- BCL-2 +/- PCa cell subpopulation dynamics and credentials BCL-2 as a vital therapeutic target in heterogeneous CRPC.