Treatment-induced neuroendocrine prostate cancer (NEPC) represents an aggressive form of castration-resistant prostate cancer (CRPC) associated with lineage plasticity and therapeutic resistance. In this study, we investigated the role of the Hippo signaling axis in the transdifferentiation from androgen receptor-positive prostate cancer (ARPC) to NEPC. RNA sequencing analyses of CRPC metastases revealed coordinated alterations in Hippo pathway components, with decreased expression of YAP1, LATS2, and TEAD2 and increased expression of LATS1, TEAD1, and the RNA splicing regulator RBFOX2 in NEPC. These transcriptional alterations were consistently observed across multiple model systems and patient samples. Epigenetic analyses demonstrated that reduced expression of YAP1, TEAD2, and LATS2 was associated with increased DNA methylation, whereas elevated TEAD1 expression correlated with DNA hypomethylation in NEPC. NEPC selectively retained TEAD1 expression, including a spliced isoform not detected in ARPC. Proteomic interactome analyses revealed that TEAD1 associated with RNA splicing factors and DNA repair proteins. Functional studies showed that TEAD1 knockdown led to the reversion of gene programs associated with epithelial differentiation. These findings indicate that the conversion of ARPC to NEPC involves coordinated loss of AR, YAP1, and REST activity alongside sustained TEAD1 expression and altered RNA processing. Our data identify TEAD1 as a transcriptional regulator associated with the NEPC state and suggest a role for TEAD1-linked transcriptional and post-transcriptional mechanisms in prostate cancer lineage plasticity.

Supplementary Figure 7 contains dot plots showing KLK2 and STEAP1 IHC H-scores for AR+/NE-metastatic sites in the UW-RA cohort.

Supplementary Figure 12 contains additional RNA-seq analyses in AR+/NE-tumors from the UW-RA cohort and SU2C-IDT cohort.

Tier 1 druggable genome targets and their associated limma values from KLK2-high vs KLK2-low and STEAP1-high vs STEAP1-low differential expression analyses.

Differentially expressed genes from STEAP1-high versus STEAP1-low analysis in UW-TAN and ECDT cohorts.

Distribution of intra-tumoral and intra-patient hypergeometric heterogeneity indices for KLK2, STEAP1, and PSMA based on IHC H-scores across samples in the UW-RA cohort.

10505 Background: Germline pathogenic variants (gPV) in prostate cancer (PCa) risk genes are associated with aggressive disease, but optimal screening thresholds for this population are unclear. We report early results from the Prostate Cancer Screening for People at Genetic Risk for Aggressive Disease (PATROL) study. Methods: PATROL is a multicenter, prospective study enrolling participants ≥40 years with a gPV in at least one of 13 PCa risk genes. Biopsy is recommended using age-specific prostate-specific antigen (PSA) thresholds: > 1.0 ng/mL (< 50y), > 1.5 (50–59y), > 2.0 (≥60y). Prostate multiparametric MRI is encouraged at baseline and within 1 year of biopsy. Clinically significant PCa (csPCa) was defined as Grade Group (GG) ≥2 (NCT04472338). Results: As of 12/1/2025, 436 participants were enrolled; 69% carried BRCA1/2 gPVs ( BRCA2 46%, BRCA1 22%), 12% carried mismatch repair gene variants, and gPVs in other genes were each ≤7%. Overall, 106 participants underwent 119 on-study biopsies (median age 61 [IQR 53–68]) with a median PSA 2.3 ng/mL [IQR 1.3–3.9]). GG1 disease was detected in 21/119 (18%) biopsies and csPCa in 21/119 (18%) biopsies. Among csPCa, the median PSA was 3.2 ng/mL (IQR 2.2-4.1), and 76% (16/21) had a PIRADS 4-5 lesion. Fifteen (71%) and 14 (67%) of GG1 and csPCa, respectively, were identified in participants with BRCA1/2 gPVs. In multivariable logistic regression adjusting for age, PSA, and genetic status, PI-RADS 4-5 was associated with csPCa (OR 12.2, 95% CI 3.3-45.4). Of the 17 men with GG1 PCa, 11 (65%) elected active surveillance. Of the 11 men on surveillance, median follow up time was 19 months, with one (9%) upgraded to GG ≥2 and who underwent definitive treatment. In total, 25 participants underwent definitive treatment; 18 with initial diagnosis of csPCA, six GG1 who elected for definitive treatment and one enrollee with GG1 upgraded to GG ≥2. Of the 25 patients who elected definitive treatment, 88% (22/25) of underwent surgery, two underwent radiation, and one underwent focal therapy. Of surgery patients, there were no postoperative complications. At a median follow-up time of 16 months, all currently have undetectable PSA, and one patient required salvage radiation therapy. Conclusions: Age-specific PSA-driven biopsy in gPV carriers yielded ~20% csPCa detection, with two-thirds occurring at PSA < 4 ng/mL (common biopsy threshold). MRI (PI-RADS 4–5) strongly predicted csPCa and may improve inherited-risk screening algorithms. With limited follow-up, surveillance of low-risk PCa among gPV carriers appears to be feasible, and definitive treatment of gPV carriers found with csPCa is effective. Clinical trial information: NCT04472338 .

BACKGROUND:Prostate-specific antigen (PSA) testing to screen for prostate cancer is controversial. An alternative approach, Stockholm3, combines PSA, plasma protein biomarkers, polygenic risk, and clinical factors into a multivariable risk score. OBJECTIVE:To compare detection of clinically significant prostate cancer (csPC) using PSA and Stockholm3 in a population-based screening with short-term follow-up. DESIGN:Secondary analysis of the baseline round of the prospective STHLM3-MRI (Prostate Cancer Screening Using a Combination of Risk-Prediction, MRI, and Targeted Prostate Biopsies) randomized screening trial in men aged 50 to 74 years who had PSA and Stockholm3 screening. Men with abnormal screening tests (PSA ≥3 ng/mL or Stockholm3 ≥11) were randomly assigned (2:3) to systematic biopsy or magnetic resonance imaging with systematic and targeted biopsies for lesions with a Prostate Imaging Reporting and Data System score of 3 or greater. Cancer diagnosed within 2 years was identified through linkage to the Swedish National Cancer Register; cancer after a negative baseline test was classified as false negative. (ClinicalTrials.gov: NCT03377881). SETTING:Stockholm region, Sweden, 2018 to 2020. PARTICIPANTS:Men aged 50 to 74 years who had PSA and Stockholm3 screening. INTERVENTION:Prostate-specific antigen and Stockholm3 tests at baseline. MEASUREMENTS:Clinically significant prostate cancer (grade group ≥2) within 2 years of baseline. RESULTS:Among 12 670 men, 443 (3.5%) were diagnosed with csPC. Decision curve analysis showed higher net benefit for Stockholm3 versus PSA across a range of decision thresholds for biopsy, indicating fewer unnecessary biopsies and fewer missed csPC cases. Stockholm3 (≥11) had a false-negative rate of 10% (43 of 443) and a false-positive rate of 11% (1289 of 12 227), whereas PSA (≥3 ng/mL) had a false-negative rate of 26% (116 of 443) and a false-positive rate of 10% (1203 of 12 227). Correspondingly, sensitivity was 90% (95% CI, 87% to 93%) for Stockholm3 and 74% (CI, 69% to 78%) for PSA, with similar specificity (89% vs. 90%). LIMITATIONS:Participation was approximately 25% of invited men; follow-up was limited to 2 years; and the cohort was predominantly Swedish or European, which may limit generalizability. CONCLUSION:In this screening cohort with short-term follow-up, Stockholm3 provided greater clinical net benefit than PSA for detecting csPC, driven by fewer false-negative results, although follow-up was limited to 2 years. PRIMARY FUNDING SOURCE:Swedish Research Council, Swedish Prostate Cancer Society, Stockholm Region, and the Swedish Cancer Society.

Supplementary Figure 9 contains donut plots showing the distribution of tumor expressing only one marker, both markers or neither marker for each KLK2-STEAP1, STEAP1-PSMA, and KLK2-PSMA pair across molecular phenotypes and across H-score thresholds.

IHC H-scores of UW-RA samples, including phenotypes as defined by IHC.

Supplementary Figure 10 shows UMAP projections of single-cell RNA-seq data from five additional AR+/NE-metastatic prostate cancer samples.

Distribution of expression and co-expression between KLK2, STEAP1, and PSMA based on IHC H-scores across samples in the UW-RA cohort.

PURPOSE:The recommendations discussed on the early detection of prostate cancer provide a framework to facilitate clinical decision-making in the implementation of prostate cancer screening and follow-up. MATERIALS AND METHODS:The Early Detection of Prostate Cancer Guideline was reviewed in 2025 and updated through the AUA amendment process. This process involved reviewing and integrating newly published literature into the previously established Guideline. The methodologist updated the original Guideline search strategy to systematically search Ovid MEDLINE and Embase for new evidence published between November 2022 and December 2024. RESULTS:The Early Detection of Prostate Cancer Amendment Panel updated evidence- and consensus-based Guideline statements to provide guidance on prostate cancer screening, imaging and biomarker use, initial and repeat biopsies, and biopsy technique. CONCLUSIONS:This update provides several new insights, including revised strength of evidence based on recently published literature on the use of MRI in biopsy-naïve patients and biopsy techniques, updates on available biomarkers, and revised recommendations for atypical small acinar proliferation (ASAP). This Guideline will require future review and updates, as early detection and diagnostic strategies in this space continue to evolve.

Log2(TPM+1) values in UW-RA samples, including phenotypes as defined by RNA-seq.

Gene set enrichment results from KLK2-high versus KLK2-low analysis in UW-TAN and ECDT.

BACKGROUND:Inherited (germline) pathogenic and likely pathogenic variants (gPVs) in key genes associated with increased risk of prostate cancer (PCa) now warrant more attentive PCa screening per National Comprehensive Cancer Network (NCCN) guidelines-e.g., BRCA2, HOXB13, ATM, BRCA1, MSH2, MSH6, CHEK2 and TP53. However, the optimal early detection strategy for gPV carriers, including use of age-adjusted PSA thresholds and prostate imaging may be refined. and as a means to investigate novel biomarkers. STUDY DESIGN:'Prostate Cancer Screening for People at Genetic Risk of Aggressive Disease' (PATROL) is a multicentre, prospective early detection study for individuals at increased risk for PCa due to carrying a gPV in a PCa risk gene. ENDPOINTS:The primary endpoint is to determine the positive predictive value of pre-defined age-directed prostate-specific antigen (PSA) level thresholds and prostate-specific imaging, e.g., multiparametric magnetic resonance imaging (MRI) for clinically significant PCa on biopsy for individuals at risk of PCa due to a gPV. Exploratory endpoints include characterising clinicopathological characteristics of PCa and patient-reported outcomes. Biospecimens will be collected to evaluate emerging clinical and research biomarkers. PATIENTS AND METHODS:Key eligibility includes: individuals aged ≥40 years who carry a gPV in an eligible gene, who have no prior diagnosis of PCa, do not have another active malignancy, and provide informed consent. Study procedures include annual physical examination and PSA. Imaging with MRI is optional at baseline and recommended if the PSA level is above the protocol-recommended PSA level threshold. Participants will be offered prostate biopsy for any clinical concern, PSA level >1.0 ng/mL if aged <50 years; PSA level >1.5 ng/mL if aged 50-59 years; PSA level >2.0 ng/mL if aged ≥60 years. If PCa is diagnosed, clinical care is determined by the participant and treating physician. If opting for active surveillance, study procedures will be collected annually for 10 years or until definitive treatment. If definitive treatment, study procedures will be collected for an additional 1 year. Long-term clinical outcomes will be collected annually until the study closes.

Distribution of KLK2 and STEAP1 single cell mRNA expression in cells from ARPC samples across MSK scRNA dataset.

Abstract Kallikrein 2 (KLK2) and six-transmembrane epithelial antigen of the prostate 1 (STEAP1) are two cell surface targets with relevance for prostate cancer therapy. The objective of this study was to characterize the expression landscape of KLK2 and STEAP1 in metastatic castration-resistant prostate cancer (mCRPC) and to define associated transcriptomic, genomic, and epigenomic features. We analyzed a total of 1,095 patient samples from three mCRPC cohorts, including in situ studies of rapid autopsy cases and patient-derived xenograft models. We found that KLK2 and STEAP1 expression is strongly enriched in androgen receptor (AR)–positive tumors and largely absent in neuroendocrine and double-negative phenotypes. Within AR+ tumors, pairwise comparisons revealed coexpression and high combined positivity rates for STEAP1, KLK2, and prostate-specific membrane antigen, suggesting that cotargeting any two of these antigens increases overall tumor coverage. Analysis of samples from a rapid autopsy cohort, which enabled assessment of intra- and intertumoral diversity, showed comparable degrees of expression heterogeneity for KLK2 and STEAP1. Antigen expression correlated positively with AR genomic alterations and serum prostate-specific antigen levels and negatively with RB1 and PTEN loss. Transcriptomic and epigenome analyses demonstrated distinct mechanisms governing antigen expression: KLK2 showed a strict AR dependence with coordinated AR/FOXA1/HOXB13 binding and enhancer activation, whereas STEAP1 was only partially AR-dependent and additionally regulated by locus-specific DNA methylation changes. Furthermore, KLK2 and STEAP1 expression states were associated with distinct transcriptional programs and immune microenvironmental features. Implications: These findings establish KLK2 and STEAP1 as key prostate adenocarcinoma-lineage antigens and provide critical insights to inform the rational design and clinical development of cell surface antigen–directed therapies in prostate cancer.

Results from predictive model integrating somatic alterations and serum PSA to estimate the probability that a sample is positive for the given antigen.