Jie Bao

Drug target proteome profiling identifies HES1-driven mitotic catastrophe in ovarian serous carcinoma.

Ovarian high-grade serous cancer (HGSC) is the most aggressive ovarian cancer subtype with limited treatment options. We identify the PDPK1 inhibitor BX-912 as a promising candidate, showing strong single-agent activity and synergy with the PARP inhibitor olaparib, independent of BRCA status. Unexpectedly, BX-912 induces multinucleation, a phenotype not seen with other PDPK1 inhibitors. Proteome Integral Solubility Alteration (PISA) assay reveals HES1 as a functional off-target, while structural modeling suggested BX-912 acts as a protein-protein interaction modulator, driving nuclear accumulation of HES1 complexes and hence inducing mitotic catastrophe. Cell-cycle analyses confirm enhanced DNA damage response and G2/M arrest when combined with olaparib. These findings uncover a novel mechanism for BX-912, establish HES1 inhibition as a therapeutic strategy in HGSC, demonstrate proteomics' power to reveal hidden drug activities, and propose sequential cell-cycle targeting to improve treatment efficacy.

Ex Vivo Immuno-Oncology Platform Reveals Spatial T-cell Infiltration Patterns Linked to ATR Inhibition Responses in High-Grade Serous Ovarian Cancer

Abstract Identifying new therapeutic approaches in high-grade serous ovarian cancer (HGSC) requires the development of more accurate preclinical models that replicate the patient-specific tumor and its microenvironment. To address this, we established immunocompetent patient-derived cultures (iPDC) for HGSC, cultured on a physiologically relevant human omentum gel matrix. We developed a high-throughput platform that combines drug testing, histologic analysis, genomic profiling, single-cell studies, and spatial biomarker discovery. Our results from 47 tumors showed that iPDCs recapitulated the tumor genomic and histologic characteristics while also retaining the intratumoral immune cells. The iPDC treatment responses correlated significantly with the patients’ clinical treatment responses. Using iPDCs and single-cell RNA sequencing, we identified potentially effective therapeutic options for patients with recurrent HGSC linked to distinct tumor cell states and mechanisms of resistance. High-throughput drug response profiling with single-cell imaging identified ataxia telangiectasia and Rad3-related inhibitor (ATRi) combined with an immunotherapy targeting autotaxin as a promising new combination treatment for HGSC. Using hyperplexed imaging and spatial analysis, we discovered that ATRi responses were associated with significant increases in both intra- and peritumoral T-cell infiltration, particularly in PD-1+ CD8+ T cells. Additionally, the ATRi-induced reactivation of CD8+ T cells was linked to spatial interactions with replication stress–positive tumor cells. Thus, our iPDC platform presents a representative high-throughput ex vivo model to advance precision oncology in HGSC, uncovering the ATRi-immunotherapy combination as a potentially effective therapeutic option for clinical translation.