Cyrill A. Rentsch

PURPOSE: Intravesical Bacillus Calmette-Guérin (BCG) is highly effective in non–muscle-invasive bladder cancer (MIBC) but has not been evaluated in MIBC. The recombinant BCG vaccine VPM1002BC (rBCG) has potentially enhanced immunogenicity and an improved safety profile. We investigated neoadjuvant intravesical rBCG combined with chemoimmunotherapy in MIBC. PATIENTS AND METHODS: SAKK 06/19 was an open-label single-arm phase II trial for cT2-T4a N0-1 MIBC eligible for cisplatin and radical cystectomy with lymph node dissection (RC-LND). rBCG was instilled once per week three times starting on day 1. Atezolizumab was administered on day 1 for a total of four doses, and cisplatin/gemcitabine was started on day 22 for four cycles followed by RC-LND. Adjuvant atezolizumab was only administered in the case of >yT1 ypN0. The primary end point was centrally reviewed pathologic complete response (pCR, ypT0 ypN0). Based on Simon's minimax two-stage design with H0 pCR ≤35%, H1 pCR ≥55%, one-sided alpha 5%, and power 80%, 46 patients were needed. Secondary end points included pathologic overall response (PaR, ≤ypT1 ypN0), event-free survival (EFS), overall survival (OS), and safety. RESULTS: Forty-seven patients were included between April 2022 and April 2025. Seven patients did not undergo RC-LND (six declined, one unfit for surgery). rBCG was instilled in 95%, and 78% had all three doses. Centrally reviewed pCR was 68% (27 of 40; one-sided 95% CI lower boundary 53%), and PaR was 83% (33 of 40; 95% CI, 67 to 93). Treatment-related adverse events (any grade, grade 3, grade 4) were 42%, 9%, and 0% for rBCG; 55%, 15%, and 2% for atezolizumab; and 96%, 38%, and 17% for chemotherapy. CONCLUSION: To our knowledge, this is the first trial combining intravesical rBCG with chemoimmunotherapy in MIBC, demonstrating high pCR and PaR rates that warrant further investigation in prospective randomized trials.

Patient-derived organoids (PDOs) are becoming increasingly important in prostate cancer (PCa) translational research. However, direct proof-of-concept studies demonstrating their ability to model disease evolution, identify relevant biomarkers, and accurately predict treatment response in PCa patients, remain scarce. Here, we report the establishment of serially transplantable xenografts series derived from two advanced PCa PDO lines, which can be further re-cultured as organoids. Newly-generated model series maintain key phenotypic, genomic, and functional characteristics of the original patient tumors, and emulate relevant molecular subtypes of advanced PCa. Single-cell RNA sequencing (scRNA-seq) analysis uncovers transcriptomic differences between xenograft and organoid models, as well as signaling pathways which are largely preserved and can be targeted ex vivo. Functional drug profiles correlate with molecular and clinical attributes, as exemplified by response to androgen receptor (AR) pathway inhibitors and glucocorticoid-mediated AR signaling activation. Longitudinal scRNA-seq analysis of perturbed PDOs identifies a rare PROX1+/ALDH1A1+ cell population, which pre-exist in the treatment-naive setting and is significantly enriched upon androgen deprivation. Notably, this cell population is similarly enriched in post-treatment samples of the original patient and is associated with aggressive AR-negative PCa molecular subtypes, suggesting a potential link with PCa progression. Our study provides proof-of-concept evidence that organoids can mirror PCa patient-specific drug sensitivity profiles and molecular paths of disease progression, uncovering pertinent biomarkers. Ultimately, our organoid-xenograft model series provide a modular and scalable platform that can readily be used for mechanistic and translational studies.

Circulating tumor cell (CTC) clusters are highly efficient metastatic seeds in various cancers. Yet, their genetic heterogeneity and clonal architecture is poorly characterized. Using whole-exome sequencing coupled with phylogenetic inference from CTC clusters of patients with breast and prostate cancer, as well as mouse cancer models alongside barcode-mediated clonal tracking in vivo, we demonstrate oligoclonal composition of individual CTC clusters. These results improve our understanding of metastasis-relevant clonal dynamics.

Malignancies of epithelial tissues, called carcinomas, account for most cancer cases. Research has largely focused on correlating different carcinoma subtypes to genetic alterations. However, as well as a rewiring in the signalling networks, carcinoma progression is accompanied by mechanical changes in the epithelial cells and the extracellular matrix. Here we reveal intricate morphologies in the basement membrane at the onset of bladder cancer and propose that they emerge from a mechanical instability upon epithelial overgrowth. We imaged mouse and human bladder tissue and performed differential growth simulations, and found that stiffness changes in the different mucosa layers can result in aberrant tissue morphologies. The resulting thickening, wrinkles and folds resemble early papillary tumours and carcinomas in situ. Atomic force microscopy confirmed local stiffness changes in the pathological basement membrane. Our findings suggest a possible mechanical origin of the different bladder carcinoma subtypes and may guide future developments in treatment and prophylaxis.

Patient-derived organoids (PDOs) offer new opportunities to model various cancers. However, their application in prostate cancer (PCa) has been hampered by poor success rates and overgrowth of cell types which are not representative of the patient samples. By exploiting a cohort of 164 PCa patient samples and tuning several culture parameters, we show that an extracellular matrix-free (ECM)-free culture system increases the take-rate of PDOs with luminal-like and PCa features. Single-cell RNA sequencing (scRNA-seq) reveals that ECM-free PDOs comprise cell populations associated with known PCa signatures and exhibit transcriptomic resemblance with their respective parental tumors. In addition, we define organoid-associated cell type signatures and identify markers discriminating tumors versus benign cells ex vivo and in situ . Furthermore, we generate the first prostate PDO single-cell atlas integrating previously-published scRNA-seq datasets and our newly- generated data. We show that Matrigel-based organoid cultures derived from primary PCa are essentially composed of benign-like epithelial cells, irrespective of the dataset or the malignant nature of the tissue of origin. In contrast, ECM-free conditions maintain heterogenous patient-specific luminal tumor cell populations and enrich in intermediate cell types. Ultimately, our work will significantly enhance the potential of PDOs in basic and translational PCa research.

Most men with prostate cancer (PCa), despite potentially curable localized disease at initial diagnosis, progress to metastatic disease. Despite numerous treatment options, choosing the optimal treatment for individual patients remains challenging. Biomarkers guiding treatment sequences in an advanced setting are lacking. To estimate the diagnostic potential of liquid biopsies in guiding personalized treatment of PCa, we evaluated the utility of a custom-targeted next-generation sequencing (NGS) panel based on the AmpliSeq HD Technology. Ultra-deep sequencing on plasma circulating free DNA (cfDNA) samples of 40 metastatic castration-resistant PCa (mCRPC) and 28 metastatic hormone-naive PCa (mCSPC) was performed. CfDNA somatic mutations were detected in 48/68 (71%) patients. Of those 68 patients, 42 had matched tumor and cfDNA samples. In 21/42 (50%) patients, mutations from the primary tumor tissue were detected in the plasma cfDNA. In 7/42 (17%) patients, mutations found in the primary tumor were not detected in the cfDNA. Mutations from primary tumors were detected in all tested mCRPC patients (17/17), but only in 4/11 with mCSPC. AR amplifications were detected in 12/39 (31%) mCRPC patients. These results indicate that our targeted NGS approach has high sensitivity and specificity for detecting clinically relevant mutations in PCa.

Sarcomatoid Urothelial Bladder Cancer (SARC) is a rare and aggressive histological subtype of bladder cancer for which therapeutic options are limited and experimental models are lacking. Here, we report the establishment of a long-term 3D organoid-like model derived from a SARC patient (SarBC-01). SarBC-01 emulates aggressive morphological, phenotypical, and transcriptional features of SARC and harbors somatic mutations in genes frequently altered in sarcomatoid tumors such as TP53 (p53) and RB1 (pRB). High-throughput drug screening, using a library comprising 1567 compounds in SarBC-01 and conventional urothelial carcinoma (UroCa) organoids, identified drug candidates active against SARC cells exclusively, or UroCa cells exclusively, or both. Among those, standard-of-care chemotherapeutic drugs inhibited both SARC and UroCa cells, while a subset of targeted drugs was specifically effective in SARC cells, including agents targeting the Glucocorticoid Receptor (GR) pathway. In two independent patient cohorts and in organoid models, GR and its encoding gene NR3C1 were found to be significantly more expressed in SARC as compared to UroCa, suggesting that high GR expression is a hallmark of SARC tumors. Further, glucocorticoid treatment impaired the mesenchymal morphology, abrogated the invasive ability of SARC cells, and led to transcriptomic changes associated with reversion of epithelial-to-mesenchymal transition, at single-cell level. Altogether, our study highlights the power of organoids for precision oncology and for providing key insights into factors driving rare tumor entities.