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PubMed2025

Clinicopathologic and Molecular Analysis of Colorectal Carcinomas With Spectrum of Neuroendocrine Carcinoma Components.

The genetics of colorectal carcinoma (CRC) with neuroendocrine differentiation remain poorly understood; recent studies focusing on pure neuroendocrine carcinomas (NECs) demonstrated mutation profiles closely resembling colorectal adenocarcinomas (ACAs) with more frequent BRAF mutations and Rb/p16 pathway dysregulation. However, pathogenesis of mixed neuroendocrine-non-neuroendocrine neoplasms (MiNENs) and ACAs with minor NEC component (AMiNECs) remains controversial. We aimed to define the behavior and molecular underpinnings of these tumors in comparison with conventional ACAs. In total, 20 NECs, 10 MiNENs, and 8 AMiNECs were compared with 100 controls with ACAs. Well-differentiated neuroendocrine tumors of any grade were excluded. CRCs with NEC components presented at a slightly earlier age (mean, 59 vs 65 years; P = .24) in a similar sex distribution (male:female, 1:1.11 vs 1.04:1; P = .97). The majority of cases arose either from a precursor adenoma (42%) or in the setting of inflammatory bowel disease (18%), whereas 5 of 10 cases (50%) originating from the rectum were human papillomavirus driven. Despite similarity in tumor size and depth of invasion among all groups, CRCs with NEC components showed more frequent lymph node and distant metastases (P < .001 each), leading to more advanced disease stage (stage III/IV; P < .001) and worse 5-year survival outcomes (35.4% for NECs, 30% for MiNENs, and 41.6% for AMiNECs vs 85.1% for ACAs; P < .001), compared with ACAs. Next-generation sequencing revealed more frequent BRAF (40% vs 3%; P < .001) and BRCA1 alterations (15% vs 1%; P = .001) in NECs compared with ACAs. Genomic alterations in RB1 were exclusively found in NECs (10%) and MiNENs (20%). In conclusion, the presence of any NEC component (from AMiNEC to pure NEC) in CRC carries a dismal prognosis. Yet, these tumors are more likely to harbor potentially targetable mutations such as BRAF p.V600E and alterations in BRCA1/2, which are of therapeutic value.

Humans↗

PubMed2026

Epithelial tumor suppressor deletion promotes neuroendocrine differentiation in bladder cancer and reveals homoharringtonine as a candidate vulnerability.

Neuroendocrine bladder carcinoma (NEBC) is a highly aggressive malignancy with unresolved lineage determinants and limited preclinical models, hindering mechanistic investigation and therapeutic development. Here, we sought to assess whether bladder epithelial-derived models are competent to acquire neuroendocrine lineage programs under defined tumor suppressor alterations and to identify candidate therapeutic vulnerabilities in these systems. We integrated genomic and transcriptomic analyses of human NEBC with genetically engineered mouse models, epithelial-derived bladder organoids, and patient-derived NEBC models. Human NEBC exhibited dominant RB1 and TP53 alterations and an epithelial transcriptional continuum consistent with lineage plasticity. In vivo, intravesical Adeno-Cre-mediated tumor suppressor deletion predominantly generated sarcoma-like tumors, whereas epithelial-restricted organoid models recapitulated the molecular and neuroendocrine features of human NEBC, supporting epithelial lineage competence for neuroendocrine differentiation. Patient-derived models and human NEBC specimens further supported epithelial identity in NEBC. Using these complementary platforms, drug screening identified homoharringtonine (HHT) as a candidate therapeutic vulnerability in the tested NEBC systems. HHT suppressed neuroendocrine marker expression, induced apoptosis, and attenuated IL6-JAK-STAT3 signaling. Together, these findings describe complementary epithelial-derived NEBC models and support further investigation of HHT as a candidate therapeutic vulnerability.

Journal Article↗

PubMed2026

TFAP2B and FOXC1 are associated with biologically and clinically distinct differentiation states in triple-negative breast cancer.

Triple-negative breast cancer (TNBC) comprises biologically distinct subtypes, including luminal androgen receptor (LAR) tumors, but routine immunohistochemical markers incompletely capture lineage-associated differentiation states. We investigated TFAP2B, an AP-2 family transcription factor linked to epithelial differentiation, and FOXC1, a basal-like-associated transcription factor, as complementary markers of luminal and basal differentiation in TNBC. In a tissue microarray of 105 TNBCs, tumors were stratified as TFAP2B-dominant, FOXC1-dominant, or double-negative according to relative marker predominance and characterized using lineage, proliferation, molecular, immune, and chemotherapy-response parameters. TFAP2B-dominant tumors were associated with a coherent luminal phenotype, including apocrine/lobular enrichment, strong MUCL1 and AR expression, high CK18, low SOX10, reduced proliferation, frequent wild-type p53 patterns and retained RB1 expression, and low PD-L1 expression. FOXC1-dominant tumors showed contrasting basal-like features. These associations were independently supported at the transcriptional and genomic levels in the METABRIC TNBC cohort. FOXC1-dominant tumors also showed more frequent chemotherapy-induced downstaging than TFAP2B-dominant tumors. Together, we identify TFAP2B as a marker associated with luminal differentiation in TNBC and support combined TFAP2B/FOXC1 assessment as a practical framework for identifying clinically relevant TNBC differentiation states.

Humans↗

PubMed2026

POU2F3 expression in lung squamous cell carcinoma: transcriptomic and immunohistochemical profiling with prognosis.

BACKGROUND: Lung squamous cell carcinoma (LUSC) lacks well-defined molecular targets. This study investigated the clinical and biological relevance of POU class 2 homeobox 3 (POU2F3), a tuft cell-associated transcription factor, in LUSC. METHODS: RNA sequencing data of patients with LUSC from The Cancer Genome Atlas (TCGA cohort, n = 190) was analysed and compared to a cohort of surgically resected cases analyzed via immunohistochemistry (IHC cohort, n = 137). Prognostic impact was assessed via survival analyses. Transcriptomic features, pathway enrichment, and immune profiles were evaluated via differentially expressed gene analysis, Gene Set Enrichment Analysis, and CIBERSORTx. RESULTS: High POU2F3 expression independently predicted poor overall survival in the TCGA cohort (HR = 2.06, 95% CI: 1.04-4.08, P = 0.039). In contrast, POU2F3 expression was not prognostic in the IHC cohort (P = 0.995). Morphologically, POU2F3-positive tumours were enriched for non-keratinizing and poorly differentiated subtypes. Transcriptomic analysis showed suppression of proliferation and immune-related pathways (FDR < 0.001), with suggestive enrichment of the TGF-β (FDR = 0.143) and p53 (FDR = 0.229) signaling pathways. On immune deconvolution, POU2F3-high tumours showed a nominal increase in activated dendritic cells, which did not withstand multiple testing correction. POU2F3 protein was detected in 12.4% of tumours and was significantly associated with p53 or RB1 abnormalities (single or double) (P = 0.028). CONCLUSIONS: POU2F3 marks a transcriptionally distinct, early-stage subtype of LUSC with keratinization-related features. Its prognostic relevance appears context-dependent and requires prospective validation in uniformly treated cohorts.

Humans↗

PubMed2026

Frequency and clinical features of germline pathogenic variants in sarcoma: a case-control study.

BACKGROUND: Germline multigene panel testing is not yet integrated into standard care for patients with sarcoma. This study aimed to assess the frequency and distribution of germline pathogenic variants in patients with sarcoma compared with cancer-free controls and identify differences between patients with and without germline pathogenic variants. METHODS: This retrospective cohort included 488 sarcoma patients and 2440 cancer-free controls matched 1:5 by age, sex, and ethnicity. Multigene panel testing was performed between 2016 and 2024 at a single germline testing laboratory. The frequency of germline pathogenic variants in selected genes was compared using Fisher exact test with odds ratios (ORs) and 95% confidence intervals. Additionally, within the case-only cohort, clinical characteristics were evaluated to assess associations with the presence of germline pathogenic variants in any gene. RESULTS: Among 488 patients with sarcoma, 67.8% (n = 331) were female, with a median age at sarcoma diagnosis of 47 years (range = 0.5-87.5 years). Cases had a higher frequency of germline pathogenic variants compared with controls (26.2% vs 10.5%; OR = 3.05, P < .001). We observed a higher frequency of germline pathogenic variants in TP53, BRCA2, CHEK2, NF1, SDHA, BRIP1, POT1, RB1, and CDH1 among patients with sarcoma compared with controls. Age at sarcoma diagnosis did not differ between groups. CONCLUSIONS: This study confirms the high detection rate of germline pathogenic variants in patients with sarcoma and describes several associated genes. These findings indicate that age at sarcoma diagnosis may not reliably predict germline pathogenic variants. Expanding germline testing for patients with sarcoma would enhance personalized treatment strategies and familial risk assessment.

Humans↗

PubMed2026

Mast cell leukemia with complex genomic alterations in an elderly patient with prior hematologic and solid malignancies: a case report.

INTRODUCTION: Mast cell leukemia (MCL) is the rarest and most aggressive variant of systemic mastocytosis (approximately 1% of cases), with a median survival of under 2 years. Diagnosis requires ≥20% atypical mast cells in the marrow aspirate, and the disease frequently overlaps with myeloid neoplasms. CASE PRESENTATION: An 86-year-old man with paranasal sinus diffuse large B-cell lymphoma in remission since 2017 after R-CHOP and methotrexate, and prostate adenocarcinoma treated in 2019, presented with acute pancytopenia, presumed to represent lymphoma relapse. Serum tryptase exceeded 11 999 ng/mL; the aspirate showed 20% pleomorphic mast cells (CD117+, weak CD25, CD2-), confirming aleukemic MCL. Formal CMML criteria could not be confirmed due to the unavailability of monocyte differential data; however, the findings raised suspicion for an associated myeloid neoplasm, with SM with an associated hematological neoplasm remaining an alternative classification. Karyotyping was normal; next-generation sequencing revealed pathogenic variants in TP53, RB1, DAXX, ASXL1, TET2, and SRSF2, and a rare extracellular-domain KIT p.D419del. He declined inpatient midostaurin, deteriorated rapidly, and died 2 weeks later. CLINICAL DISCUSSION: This case illustrates a therapy-related MCL (plausible but unconfirmed given the non-leukemogenic profile of methotrexate and the focal nature of prostate stereotactic body radiation therapy) with a suspected associated myeloid neoplasm and complex pathogenic mutations. The KIT p.D419del extracellular domain variant is a rare non-D816V mutation; the canonical D816V was not detected on NGS, though the presence of a low-variant allele fraction D816V cannot be fully excluded due to assay sensitivity. Despite midostaurin, the disease remained aggressive. CONCLUSION: Persistent unexplained cytopenias warrant heightened suspicion of MCL, and comprehensive genomic profiling clarifies diagnosis, distinguishes overlapping myeloid disease, and informs prognosis in this aggressive, refractory neoplasm.

case report↗

PubMed2026

Landscape of genetic alterations affecting cancer genes in primary and advanced malignant phyllodes tumours.

BACKGROUND: Malignant phyllodes tumours (MPT) are aggressive breast fibroepithelial neoplasms. Their rarity has limited their genetic characterization, and associations with genetic ancestry and progression drivers remain poorly understood. Prior studies suggest two evolutionary pathways according to MED12 mutational status. We sought to determine the repertoire of somatic genetic alterations in cancer genes in primary versus metastatic/recurrent MPTs, and according to MED12 mutational status and genetic ancestry. MATERIALS AND METHODS: We analysed the paired tumour-normal targeting sequencing data (up to 505 cancer-related genes) of 31 MPTs (primary, n = 20; metastatic/recurrent, n = 11). RESULTS: Metastatic/recurrent MPTs harboured a numerically higher frequency of genetic alterations in CDKN2A/2B (55% vs. 25%). Moreover, analysis of an MPT case with paired primary and metastatic samples revealed a CDKN2A/2B homozygous deletion restricted to the metastatic sample, suggesting a role for CDKN2A/2B in progression. Compared with MED12-wild type MPTs, MED12-mutant MPTs had higher tumour mutation burden (P = 0.002), frequency of TERT promoter (82% vs. 35%; P = 0.02) and RB1 mutations (45% vs. 5%; P = 0.01). Genetic alterations in the PI3K pathway, including PIK3CA and PTEN, were only present in MED12-wild type MPTs, and absent in MED12-mutant cases (15% vs. 0%; P > 0.05). Furthermore, genetic alterations in EGFR were restricted to MPTs from patients of European genetic ancestry and absent in those of Asian ancestry (43% vs. 0%; P > 0.05). CONCLUSIONS: Taken together, the repertoire of genetic alterations in primary and metastatic/recurrent MPTs shows overlap, and CDKN2A/2B homozygous deletions may play a role in progression. Additionally, molecular profiles of MPTs may vary according to genetic ancestry and MED12 mutational status.

Humans↗

PubMed2026

PRDM16 Regulates Prostate Cancer Cell Dormancy and Prevents Bone Metastatic Outgrowth.

UNLABELLED: Understanding dormancy in prostate cancer is challenging because of model availability. In this study, using murine and human prostate cancer cell lines, we generated a stress-induced model of dormancy in vitro and demonstrated that the phenotype could be sustained upon intrailiac artery delivery into the bone marrow microenvironment. RNA sequencing analysis revealed that the transcription factor positive regulatory domain-containing 16 (PRDM16) was commonly upregulated in dormant prostate cancer cells compared with controls. Furthermore, bone marrow-disseminated prostate cancer cells from primary orthotopic tumors were largely positive for PRDM16. Genetic ablation and forced ectopic expression supported a role for PRDM16 in maintaining prostate cancer dormancy in vitro and in vivo. Clinically, PRDM16 negatively correlated with disease recurrence and with the E2F cell-cycle program in disseminated tumor cells derived from the bone marrow of patients with prostate cancer. Gene enrichment and characterization studies implicated PRDM16 as a regulator of metabolic and cell-cycle pathways. Chromatin immunoprecipitation-qPCR further revealed that PRDM16 binds upstream of the promoter of RB1, a potent repressor of E2F activity. Overall, this study developed a straightforward method for inducing cancer cell dormancy and applied this approach to find that PRDM16 governs an intrinsic dormancy program in prostate cancer. SIGNIFICANCE: PRDM16 initiates a dormancy program in prostate cancer cells that is sustained in the bone marrow microenvironment, highlighting PRDM16 as a potential biomarker for relapse and target for eliminating dormant cancer cells.

Male↗

PubMed2026

Comparative analysis of distinct genomic landscapes in young-onset gBRCA1/2 breast cancer.

Carriers of germline BRCA1/2 pathogenic variants (gBRCA1/2 PVs) have elevated young-onset breast cancer risk. To define the pretreatment genomic landscapes of young-onset gBRCA-associated breast cancer, we evaluated 136 treatment-naive tumors diagnosed before age 50 in the prospective POSH study and 66 noncarriers from The Cancer Genome Atlas. Using whole-exome sequencing, we analyzed somatic variation, allele-specific loss of heterozygosity (asLOH), homologous recombination deficiency (HRD), and single-base substitution (SBS) signatures. gBRCA1 and gBRCA2 breast cancers had high rates of asLOH but differed significantly in average HRD scores and median SBS composition of signatures SBS1 (aging-associated), SBS18 (ROS-associated), and SBS3 (HRD-associated). Compared with gBRCA2 tumors, gBRCA1 tumors with asLOH were significantly enriched for alterations in hallmark ROS, DNA repair, and epithelial-mesenchymal transition pathways. In ER-positive, HER2-negative tumors from gBRCA1/2 carriers compared with noncarriers, we found significant enrichment of RB1, TP53, FAT1, and MYC single-nucleotide variants, indels, and copy number variants associated with CDK4/6 inhibitor (CDK4/6i) resistance. Together, these findings demonstrate significant differences between gBRCA1- and gBRCA2-associated breast cancers, and preexisting CDK4/6i resistance mechanisms, supporting prospective trials comparing individualized therapy for gBRCA1 versus gBRCA2 carriers and comparing poly(ADP-ribose) polymerase inhibitors versus CDK4/6i for ER-positive gBRCA1/2-associated breast cancer.

Humans↗

PubMed2026

Detection of Tumor Suppressor Genes Rare Variants: Findings From Neuroblastoma Using Next-Generation Sequencing.

BACKGROUND/OBJECTIVES: Neuroblastomas (NB) influenced by genetic alterations, which plays significant role in disease progression. Tumor suppressor genes (TSGs) are crucial in regulating cell growth, suppressing replication, and inducing apoptosis to prevent cancer formation. However, mutations in TSGs can lead to loss of normal activity, contributing to cancer development. This study aimed to identify TSG variants in NB patients and assess their clinical significance. METHODS: One hundred two NB patients diagnosed and monitored according to the International Neuroblastoma Risk Group Staging System (INRGSS) protocol were included in this study. DNA was extracted from paraffin-embedded tissue samples, and Next-Generation Sequencing (NGS) was conducted using the Pillar ONCO/Reveal Multi-Cancer v4 panel. RESULTS: The most frequently recurring TSG variant detected was RB1, p.P793S (n = 21; 25%) followed by ATM, p.D1853N (n = 20, 19.6%).Stop-gain variants were identified in TP53 (p.R196*), FBXW7 (p.R367*), and PTEN (p.G129*). CONCLUSIONS: Our findings underscore the significance of specific TSG variants in NB, particularly in relation to disease progression and potential prognostic markers. Further research is needed to comprehensively assess the role of TSGs in NB, with an emphasis on germline variants and protein expression in larger patient cohorts.

Humans↗

PubMed2026

Prognostic value of circulating tumor DNA and copy-number alterations in patients receiving tandem [225Ac]Ac-/[177Lu]Lu-PSMA-617 therapy for metastatic castration-resistant prostate cancer: a prospective observational study.

BACKGROUND: Prostate-specific membrane antigen-targeted radioligand therapy (PSMA-RLT) demonstrates clinical efficacy in metastatic castration-resistant prostate cancer (mCRPC), yet robust biomarkers for dynamic treatment monitoring and resistance remain lacking. We investigated circulating tumor DNA (ctDNA)-derived tumor fraction (TFx) and genome-wide copy-number alterations (CNAs) as non-invasive biomarkers of treatment response and resistance biology. METHODS: Seventy-eight patients with advanced mCRPC receiving tandem [225Ac]Ac-/[177Lu]Lu-PSMA-617 were prospectively enrolled. Plasma samples collected longitudinally (n = 172) underwent ultra-low-pass whole-genome sequencing. TFx was estimated using ichorCNA, and recurrent CNAs were identified using GISTIC2.0. Associations with progression and overall survival (OS) were assessed using Cox proportional hazards models, including time-dependent analyses. RESULTS: Baseline TFx differed across metastatic disease stages (p = 0.027) and dynamic TFx changes paralleled PSA kinetics during early treatment. Modelled as a time-dependent variable, TFx was associated with a significantly increased risk of progression (HR 4.9, 95% CI 1.2-20.1, p = 0.026). Unsupervised clustering identified distinct high- and low-CNA burden groups strongly correlated with TFx (p = 8.09 × 10⁻8). High CNA burden was associated with shorter median OS (8.3 vs 13.8 months). Multivariable analysis identified baseline logPSA and logALP as independent predictors of OS. Recurrent CNAs affected key tumor suppressors (PTEN, RB1, BRCA2, ATM) and were enriched in pathways related to TP53 signalling, homologous recombination repair, and oncogenic signaling. Longitudinal analyses demonstrated persistence and expansion of specific amplifications at progression. CONCLUSIONS: ctDNA-derived TFx represents a dynamic biomarker of treatment response and progression risk, while CNA profiling provides insight into resistance mechanisms in mCRPC treated with PSMA-RLT. These findings support the integration of ctDNA-based biomarkers into clinical stratification and real-time monitoring strategies.

Humans↗

PubMed2026

ATP-Dependent Chromatin Remodelers in Prostate Cancer Progression and Therapeutic Resistance.

ATP-dependent chromatin remodelers (ACRs) have emerged as central determinants of prostate cancer (PCa) progression and therapy resistance. Organized into four mechanistically distinct families (SWI/SNF, ISWI, CHD, and INO80/SWR), ACRs govern nucleosome positioning genome-wide and thereby occupy a central position in the epigenomic regulatory landscape that dictates where and when transcription factors, including the androgen receptor (AR), can engage chromatin. This review discusses ACR dysregulation in PCa through both mutational and non-mutational mechanisms. These are illustrated by discussing how the functional consequences are highly context-dependent, varying with disease stage, prior treatment exposure, and tumor ancestry. Loss of the tumor suppressors RB1, TP53, and PTEN each generates specific ACR dependencies that are potentially therapeutically exploitable, including synthetic lethal relationships between PTEN deficiency and SWI/SNF ATPase activity. Across the spectrum of AR signaling states, from hormone-sensitive disease through therapy-resistant neuroendocrine and double-negative PCa subtypes, ACR complex composition and genomic targeting are continuously reprogrammed to enable and sustain lineage plasticity and endocrine therapy escape. Therapeutic strategies targeting SWI/SNF, ISWI, and INO80/SWR complexes are at varying stages of preclinical and clinical development and are attractive novel avenues to target therapy resistant PCa.

ATP dependent chromatin remodeling↗

PubMed2025

Targeting anti-apoptosis as a therapeutic strategy in neuroendocrine neoplasms.

BCL-2 is an anti-apoptotic protein expressed by aggressive neuroendocrine neoplasms (NENs). We report a case of a patient with a pancreatic neuroendocrine tumor (pNET) who received venetoclax, a BCL-2-targeting drug for the treatment of chronic lymphocytic leukemia. We further characterized BCL2 expression in NENs from a large multi-institutional patient cohort. Clinical data were abstracted from the records of a patient with a pNET. Next-generation sequencing of DNA (592-gene panel or whole exome) and RNA (whole transcriptome) was performed on 636 NENs of pancreatic (P-NENs), small bowel (SB-NENs), colorectal (CR-NENs), and lung (L-NENs) origin by Caris Life Sciences. Comparisons were performed against site-matched non-NEN cancers. BCL2- or MKI67- high and low cohorts were defined based on the top and bottom quartiles of gene expression. The patient with a pNET who received venetoclax had a partial response in the primary tumor that lasted 30 months. CR-, L-, and P-NENs had significantly higher expression of BCL2 compared to non-NEN counterparts. BCL2 expression was significantly higher in MKI67-high tumors among all NEN subtypes. In P-NENs, there was a higher prevalence of RB1 mutations in BCL2-high vs BCL2-low (40 vs 4.9%, P < 0.005). Patients with BCL2-high P-NENs had significantly decreased overall survival (HR 1.94, 95% CI 1.0-3.76, P = 0.047). Immune checkpoint gene expression and T cells were enriched in BCL2-high tumors across all subtypes. In summary, we report the first known case of a pancreatic NET with response to venetoclax. BCL2 expression correlated with high MKI67 expression, worse survival, and a highly immune-enriched microenvironment.

Aged↗

PubMed2026

Grade progression and high-grade transformation in neuroendocrine neoplasms.

Epithelial neuroendocrine neoplasms (NENs) comprise a biologically diverse group of malignancies that span a wide spectrum of differentiation, proliferative activity, and clinical behavior. Contemporary classifications distinguish well-differentiated neuroendocrine tumors (NETs) from poorly differentiated neuroendocrine carcinomas (NECs). However, growing longitudinal data indicate that a subset of NETs may undergo temporal evolution characterized by rising Ki-67, increasing morphologic atypia, and acquisition of genomic alterations classically associated with NEC, particularly TP53 and, less commonly, RB1 inactivation. These phenomena, referred to as grade progression and high-grade transformation, can result in tumors with NEC-like behavior despite retention of a NET molecular backbone, creating diagnostic and therapeutic ambiguity. In this review, we synthesize recent evidence on the molecular, morphologic, and clinical features of gastroenteropancreatic NET grade progression and transformation, highlight the role of clonal evolution and treatment-associated selection pressure, and discuss implications for imaging, biopsy strategy, molecular profiling, and therapy selection.

Humans↗

PubMed2026

Tumor-Intrinsic Blood and Imaging Correlatives in Advanced Prostate Cancer Treated with Combination Radiopharmaceutical Therapy and Immunotherapy.

The PRINCE trial showed the clinical activity for 177Lu-PSMA-617 in combination with pembrolizumab for metastatic castration-resistant prostate cancer. To refine patient selection and improve response monitoring strategies to this combination, we investigated candidate tumor-intrinsic biomarkers of treatment response and resistance. Methods: We performed circulating tumor DNA (ctDNA), circulating tumor cell (CTC), and PET imaging analyses at baseline, 12 wk on-treatment, and disease progression in participants enrolled in PRINCE (n = 37). We performed targeted sequencing for ctDNA quantification and genomic analysis of more than 70 prostate cancer genes. CTC enumeration was performed on the EpicSciences platform and was combined with selective single-cell whole-genome sequencing. PET imaging included serial PSMA PET as well as 18F-FDG PET imaging at baseline. Results: A low baseline ctDNA fraction and high PSMA avidity in metastatic lesions were linked to superior treatment responses and may have composite biomarker value. Genomic alterations in tumor suppressor genes TP53, RB1, or PTEN were associated with higher 18F-FDG avidity and metabolic tumor volume on 18F-FDG PET imaging and worse prognosis. At 12-wk on-treatment, both ctDNA detection and PSMA PET imaging were strong indicators of response depth and durability. At disease progression, PSMA expression on PET imaging was lower compared with baseline and supported by subclonal remodeling of ctDNA and CTC copy number profiles and by clonal expansions of tumor suppressor gene mutations. Conclusion: We provide the first integrated molecular and imaging insights into determinants of response and resistance to combined radiopharmaceutical therapy and immunotherapy in prostate cancer and propose biomarker strategies to inform future clinical development.

177Lu-PSMA-617↗