The Role of Microsatellite Instability/DNA Mismatch Repair Deficiency and Tumor Mutational Burden as Biomarkers in Predicting Response to Immunotherapy in Castration-resistant Prostate Cancer.

Large trials of immune checkpoint inhibitors (ICIs) in castration-resistant prostate cancer (CRPC) have mostly failed. Biomarker-selected CRPC patients, especially those with high microsatellite instability (MSI-H), mismatch repair deficiency (dMMR), or elevated tumor mutational burden (TMB), may benefit from single-agent ICIs. Despite their rarity in CRPC (∼2-5%), identification of MSI-H, dMMR, or TMB-H could improve patient selection for immunotherapy.

High serum sodium predicts immunotherapy response in metastatic renal cell and urothelial carcinoma.

OBJECTIVES: The development of reliable biomarkers for the prediction of immune checkpoint inhibition (ICI) response in patients with metastatic renal cell carcinoma (mRCC) and urothelial carcinoma (mUC) remains an unresolved challenge. Conventional ICI biomarkers typically focus on tumor-related factors such as PD-L1 expression. However, a comprehensive evaluation of the predictive value of serum electrolyte levels, a so far widely unexplored area, is still pending. METHODS: We conducted a post-hoc analysis of baseline sodium, potassium, chloride, magnesium and calcium levels in two independent phase 3 clinical trials: IMvigor211 for mUC comparing atezolizumab to chemotherapy, and IMmotion151 for mRCC comparing atezolizumab+bevacizumab to sunitinib. This analysis aimed to evaluate the prognostic and predictive value of these electrolyte levels in these clinical settings. A total of 1787 patients (IMvigor211 n = 901; IMmotion151 n = 886) were analyzed. RESULTS: We found a linear correlation of baseline serum sodium and chloride with prognosis across both trials, which was not found for potassium, magnesium and calcium. In multivariate analysis, the prognostic capacity of sodium was limited to patients receiving ICI as compared to the control group. Interestingly, in both studies, the chance of achieving an objective response was highest in the patient subgroup with high baseline serum sodium levels of > 140 mmol/L (IMmotion151: Complete response in 17.9% versus 2.0% in patients with mRCC with baseline sodium < 135 mmol/L). Serum sodium outperformed tumor PD-L1 expression as a predictor for immunotherapy efficacy. CONCLUSIONS: Patients exhibiting elevated serum sodium levels derive the greatest benefit from immunotherapy, suggesting that baseline serum concentration could serve as a valuable and cost-effective predictive biomarker for immunotherapy across entities.

Bellmunt risk score as a survival predictor in patients with metastatic castration-resistant prostate cancer.

BACKGROUND: The prognosis of metastatic castration-resistant prostate cancer (mCRPC) is influenced by numerous individual factors. Despite various proposed prognostic models, the clinical application of these remains limited, probably due to complexity. Our study aimed to evaluate the predictive value of the Bellmunt risk score, which is well-known for urothelial carcinoma and easily assessed, in mCRPC patients. METHODS: The Bellmunt risk score was calculated from three risk factors (Eastern Cooperative Oncology Group Performance Status (ECOG PS) ≥1, serum hemoglobin <10 g/dL, presence of liver metastases) in 125 patients who received first-line mCRPC treatment between 2005 and 2023. In addition, a modified score was established (one point each for hemoglobin <10 g/dL and the presence of liver metastases added to the ECOG PS). Associations with overall survival (OS) under first- and second-line therapy were tested using Cox regression analyzes, log-rank tests, concordance index (C-index) and time-dependent receiver operating characteristic. RESULTS: There is a significant correlation between the level of the Bellmunt risk score and shorter OS (hazard ratio: 3.23, 95% confidence interval: 2.06-5.05; log-rank p < 0.001; C-index: 0.724). The semi-quantitative modified risk score showed even better prognostic discrimination (log-rank p < 0.001, C-index: 0.764). The score and its dynamics were also predictive in the second-line setting (log-rank p < 0.001 and = 0.01; C-index: 0.742 and 0.595). CONCLUSIONS: The Bellmunt risk score is easy to assess and provides useful prognostic information in mCRPC, and can support physicians in their treatment decisions.

Biomarkers of Response to Anti-NECTIN4 Antibody-Drug Conjugate Enfortumab Vedotin in Urothelial Cancer.

Initial studies indicated that NECTIN4 expression is widespread in metastatic urothelial cancer (mUC), which led to approval of the anti-NECTIN4 antibody-drug conjugate (ADC) enfortumab vedotin (EV) for unselected patients with mUC. However, the recent literature suggests that there has been overestimation of membranous NECTIN4 expression in UC, which is a prerequisite for EV binding. It is well established from the development of Her2-targeting ADCs that treatment response is strongly dependent on membranous expression level of the relevant target antigen. In this context, it has been demonstrated that membranous NECTIN4 expression correlates with EV responses and outcomes. Another promising biomarker could be NECTIN4 copy number alteration, a genomic alteration that occurs in approximately 25% of mUC cases, which is associated with strong membranous NECTIN4 expression. Patients with NECTIN4 amplification exhibit an objective response rate of >90% to EV monotherapy and long-term survival. Given the heterogeneous expression of NECTIN4 in UC, future biomarker research is essential for the development of biomarker-driven mUC treatment strategies to further improve outcomes for patients with mUC. PATIENT SUMMARY: We reviewed current evidence on biomarkers for predicting response to enfortumab vedotin (EV) treatment for metastatic urinary tract cancer (mUC). Studies to date have shown that patients with high levels of the protein NECTIN4 on their cancer cells respond well to EV. This information has the potential to guide future treatment strategies for mUC.

Autoimmunity Against Surfactant Protein B Is Associated with Pneumonitis During Checkpoint Blockade.

RATIONALE: Immune checkpoint inhibitor-related pneumonitis is a serious autoimmune event affecting up to 20% of patients with non-small cell lung cancer, yet the factors underpinning its development in some patients and not others are poorly understood. OBJECTIVES: To investigate the role of autoantibodies and autoreactive T cells against surfactant-related proteins in the development of pneumonitis. METHODS: The study cohort consisted of non-small cell lung cancer patients who gave blood samples before and during immune checkpoint inhibitor treatment. Serum was used for proteomics analyses and to detect autoantibodies present during pneumonitis. T cell stimulation assays and single-cell RNA sequencing were performed to investigate the specificity and functionality of peripheral autoreactive T cells. The findings were confirmed in a validation cohort comprising patients with non-small cell lung cancer and patients with melanoma. MEASUREMENTS AND MAIN RESULTS: Across both cohorts, patients who developed pneumonitis had higher pre-treatment levels of immunoglobulin G autoantibodies targeting surfactant protein-B. At the onset of pneumonitis, these patients also exhibited higher frequencies of CD4+ interferon-gamma-positive surfactant protein B-specific T cells, and expanding T cell clonotypes recognizing this protein, accompanied by a pro-inflammatory serum proteomic profile. CONCLUSIONS: Our data suggest that the co-occurrence of surfactant protein-B-specific immunoglobulin G autoantibodies and CD4+ T cells is associated with the development of pneumonitis during ICI therapy. Pre-treatment levels of these antibodies may represent a potential biomarker for elevated risk of developing pneumonitis and on-treatment levels may provide a diagnostic aid. This article is open access and distributed under the terms of the Creative Commons Attribution Non-Commercial No Derivatives License 4.0 (http://creativecommons.org/licenses/by-nc-nd/4.0/).

NECTIN4 Amplification Is Frequent in Solid Tumors and Predicts Enfortumab Vedotin Response in Metastatic Urothelial Cancer.

PURPOSE: The anti-NECTIN4 antibody-drug conjugate enfortumab vedotin (EV) is approved for patients with metastatic urothelial cancer (mUC). However, durable benefit is only achieved in a small, yet uncharacterized patient subset. NECTIN4 is located on chromosome 1q23.3, and 1q23.3 gains represent frequent copy number variations (CNVs) in urothelial cancer. Here, we aimed to evaluate NECTIN4 amplifications as a genomic biomarker to predict EV response in patients with mUC. MATERIALS AND METHODS: We established a NECTIN4-specific fluorescence in situ hybridization (FISH) assay to assess the predictive value of NECTIN4 CNVs in a multicenter EV-treated mUC patient cohort (mUC-EV, n = 108). CNVs were correlated with membranous NECTIN4 protein expression, EV treatment responses, and outcomes. We also assessed the prognostic value of NECTIN4 CNVs measured in metastatic biopsies of non-EV-treated mUC (mUC-non-EV, n = 103). Furthermore, we queried The Cancer Genome Atlas (TCGA) data sets (10,712 patients across 32 cancer types) for NECTIN4 CNVs. RESULTS: NECTIN4 amplifications are frequent genomic events in muscle-invasive bladder cancer (TCGA bladder cancer data set: approximately 17%) and mUC (approximately 26% in our mUC cohorts). In mUC-EV, NECTIN4 amplification represents a stable genomic alteration during metastatic progression and associates with enhanced membranous NECTIN4 protein expression. Ninety-six percent (27 of 28) of patients with NECTIN4 amplifications demonstrated objective responses to EV compared with 32% (24 of 74) in the nonamplified subgroup (P < .001). In multivariable Cox analysis adjusted for age, sex, and Bellmunt risk factors, NECTIN4 amplifications led to a 92% risk reduction for death (hazard ratio, 0.08 [95% CI, 0.02 to 0.34]; P < .001). In the mUC-non-EV, NECTIN4 amplifications were not associated with outcomes. TCGA Pan-Cancer analysis demonstrated that NECTIN4 amplifications occur frequently in other cancers, for example, in 5%-10% of breast and lung cancers. CONCLUSION: NECTIN4 amplifications are genomic predictors of EV responses and long-term survival in patients with mUC.

Elucidating the need for prostate cancer risk calculators in conjunction with mpMRI in initial risk assessment before prostate biopsy at a tertiary prostate cancer center.

OBJECTIVE: Utilizing personalized risk assessment for clinically significant prostate cancer (csPCa) incorporating multiparametric magnetic resonance imaging (mpMRI) reduces biopsies and overdiagnosis. We validated both multi- and univariate risk models in biopsy-naïve men, with and without the inclusion of mpMRI data for csPCa detection. METHODS: N = 565 men underwent mpMRI-targeted prostate biopsy, and the diagnostic performance of risk calculators (RCs), mpMRI alone, and clinical measures were compared using receiver operating characteristic curve (ROC) analysis and decision curve analysis (DCA). Subgroups were stratified based on mpMRI findings and quality. RESULTS: csPCa was detected in 56.3%. PI-RADS score achieved the highest area under the curve (AUC) when comparing univariate risk models (AUC 0.82, p < 0.001). Multivariate RCs showed only marginal improvement in csPCa detection compared to PI-RADS score alone, with just one of four RCs showing significant superiority. In mpMRI-negative cases, the non-MRI-based RC performed best (AUC 0.80, p = 0.016), with the potential to spare biopsies for 23%. PSA-density and multivariate RCs demonstrated comparable performance for PI-RADS 3 constellation (AUC 0.65 vs. 0.60-0.65, p > 0.5; saved biopsies 16%). In men with suspicious mpMRI, both mpMRI-based RCs and the PI-RADS score predicted csPCa excellently (AUC 0.82-0.79 vs. 0.80, p > 0.05), highlighting superior performance compared to non-MRI-based models (all p < 0.002). Quality-assured imaging consistently improved csPCa risk stratification across all subgroups. CONCLUSION: In tertiary centers serving a high-risk population, high-quality mpMRI provides a simple yet effective way to assess the risk of csPCa. Using multivariate RCs reduces multiple biopsies, especially in mpMRI-negative and PI-RADS 3 constellation.

Hypermethylated SHOX2 in circulating cell-free DNA post renal cell carcinoma surgery as TNM-independent biomarker for recurrence risk.

INTRODUCTION: Adjuvant immune checkpoint inhibitor trials in renal cell carcinoma (RCC) call for improved recurrence risk stratification. Due to limitations of circulating tumor DNA (ctDNA) use in RCC, the use of hypermethylated SHOX2 gene (mSHOX2) in circulating cell-free DNA is explored as a surrogate marker for identifying high-risk patients after RCC surgery. METHODS: Liquid biopsies were collected post-surgery from 45 RCC patients (mean duration 4.3 days). Real-time polymerase chain reaction was used to analyze SHOX2 methylation in circulating cell-free DNA. Patients were categorized as mSHOX2 positive or negative by cut-off. Metastasis-free survival (MFS), cancer-specific survival (CSS), and overall survival (OS) were assessed using Cox regression and Log-rank analyses (median follow-up time: 60 months). RESULTS: 17 patients were mSHOX2 positive, showing unfavorable OS/CSS (Log-rank P = 0.004 and 0.02) and nearly 6-fold higher recurrence risk (hazard ratio 5.89, 95% CI 1.46-23.8). Multivariable Cox analysis confirmed mSHOX2 as an independent recurrence risk factor, disregarding TNM-based stratification. CONCLUSIONS: mSHOX2 effectively identifies high-risk RCC patients post-surgery, indicating minimal residual disease. This easy to implement biomarker has potential for guiding of adjuvant therapy decisions.

Feasibility of Monitoring Response to Metastatic Prostate Cancer Treatment with a Methylation-Based Circulating Tumor DNA Approach.

BACKGROUND: Metastatic prostate cancer (mPCA) poses challenges in treatment response assessment, particularly in cases where prostate-specific antigen (PSA) levels do not reliably indicate a response. Liquid biopsy, focusing on circulating cell-free DNA (ccfDNA) methylation analysis as a proxy for circulating tumor DNA, offers a non-invasive and cost-effective approach. This study explores the potential of two methylation markers, short stature homeobox 2 (SHOX2) and Septin 9 (SEPT9), as on-mPCA-treatment biomarkers. METHODS: Plasma samples were collected from 11 mPCA patients undergoing various treatments. Quantitative assessment of hypermethylated SHOX2 (mSHOX2) and SEPT9 (mSEPT9) levels in ccfDNA was conducted through methylation-specific real-time PCR. Early and overall dynamics of PSA, mSHOX2, and mSEPT9 were analyzed. Statistical evaluation employed Wilcoxon tests. RESULTS: mSHOX2 demonstrated a significant decline post-treatment in patients with a radiographic treatment response as well as in an early treatment setting. mSEPT9 and PSA exhibited non-significant declines. In individual cases, biomarker dynamics revealed unique patterns compared to PSA. DISCUSSION: mSHOX2 and mSEPT9 exhibit dynamics on mPCA treatment. This proof-of-concept study lays the groundwork for further investigation into these markers as valuable additions to treatment response monitoring in mPCA. Further validation in larger cohorts is essential for establishing clinical utility.

Expression of the microtubule-associated protein 2 (MAP2) as a potential independent prognostic marker in prostate cancer.

PURPOSE: Investigation of Microtubuli-associated Protein 2 (MAP2) expression and its clinical relevance in prostate cancer. MATERIAL AND METHODS: MAP2 expression was immunohistochemically analysed on radical prostatectomy specimens using whole block sections (n = 107) and tissue microarrays (TMA; n = 310). The staining intensity was evaluated for carcinoma, benign tissue and prostatic intraepithelial neoplasia. Expression data were correlated with clinicopathological parameters and biochemical recurrence-free survival. Additionally, MAP2 protein expression was quantitatively analysed in the serum of histologically confirmed prostate carcinoma patients and the control group using a commercial enzyme-linked immunosorbent assay. RESULTS: MAP2 staining was significantly stronger in neoplastic tissue than in non-neoplastic prostatic glands, both in whole block sections (p < 0.01) and in TMA sections (p < 0.05). TMA data revealed significantly stronger MAP2 staining in high-grade tumors. Survival analysis showed a significant correlation between strong MAP2 staining in carcinoma and shortened biochemical recurrence-free survival after prostatectomy (p < 0.001). Multivariate Cox regression analysis confirmed MAP2 as an independent predictor for an unfavourable course. Mean MAP2 serum levels for non-PCA vs. PCA patients differed significantly (non-PCA = 164.7 pg/ml vs. PCA = 242.5 pg/ml, p < 0.001). CONCLUSION: The present data support MAP2 as a novel biomarker in PCA specimens. MAP2 is correlated with tumor grade and MAP2 high-expressing PCA is associated with an increased risk of biochemical recurrence after radical prostatectomy. Future studies are necessary to evaluate MAP2 as a valuable immunohistochemical biomarker in preoperative PCA diagnostic procedures, in particular with regard to treatment modalities.

Integration of on-treatment modified Glasgow prognostic score (mGPS) to improve imaging-based prediction of outcomes in patients with non-small cell lung cancer on immune checkpoint inhibition.

INTRODUCTION: A large number of patients with non-small cell lung cancer (NSCLC) on immune checkpoint inhibition (ICI) achieve stable disease (SD) as the best overall response, which is associated with heterogeneous outcomes. In this context, complementary biomarkers that improve outcome prediction are needed. We have recently demonstrated that measuring the on-treatment modified Glasgow prognostic score (mGPS), which is based on the two serum markers C-reactive protein (CRP) and albumin, can improve outcome prediction complementary to radiological staging in metastatic renal cell carcinoma. However, this concept has not been assessed for patients with NSCLC on ICI. METHODS: We assessed the prognostic and predictive value of on-treatment mGPS at week six in patients with NSCLC treated with atezolizumab or docetaxel in the phase 3 OAK trial (NCT02008227) comprising n = 750 patients and validated the findings in the phase 2 BIRCH (NCT02031458, n = 560). RESULTS: On-treatment mGPS assessed at week six demonstrated valuable prognostic information (Hazard Ratio (HR) for mGPS low-risk vs intermediate risk 2.34 (95 % CI 1.76-3.11, p < 0.001) and vs high risk 3.56, (95 % CI 2.57-4.91, p < 0.001) in the atezolizumab-treated subgroup. On-treatment mGPS predicted overall survival more accurately than imaging using RECIST criteria (concordance index: on-treatment mGPS 0.646 (95 % CI 0.615-0.677) vs RECIST 0.606 (95 % CI 0.575-0.637)). On-treatment mGPS provides additional prognostic information to imaging-assessed treatment response at first staging, especially for the patient subgroup with SD. These findings were validated in the BIRCH trial. CONCLUSIONS: We highlight the novel concept of integrating on-treatment mGPS for improved outcome prediction in conjunction with radiological imaging for patients with NSCLC on ICI.

Ring Finger Protein 34 (RNF34) as a Prognostic Biomarker for Clear Cell Renal Cell Carcinoma.

INTRODUCTION: Ring finger proteins play pivotal roles in diverse cellular processes and are implicated in contribution to cancer. Ring finger protein 34 (RNF34) has antiapoptotic and oncogenic properties. RNF34 is upregulated during carcinogenesis and tumor progression in the colorectal adenoma-carcinoma sequence and was already described to mediate chemoresistance. In clear cell renal cell carcinoma (ccRCC), however, the role and expression patterns of RNF34 are unknown. METHODS: First, we investigated the association of RNF34 mRNA expression with clinicopathological parameters and survival using data obtained from The Cancer Genome Atlas (TCGA) ccRCC cohort (N = 533). To assess RNA34 protein expression, we performed immunohistochemical (IHC) staining of an established ccRCC cohort (University of Bonn) in a tissue microarray (TMA) format. This validation cohort contains 109 primary ccRCC samples. IHC data were associated with clinicopathological parameters and overall survival (Kaplan-Meier analysis). Adjustment for covariables was done using the Cox regression model. RESULTS: RNF34 expression is correlated with adverse clinicopathological parameters. Survival analysis revealed an association between RNF34 expression and shortened survival. Cox regression analysis confirmed RNF34 expression as an independent prognostic parameter. CONCLUSION: Our study provides evidence for RNF34 as a prognostic biomarker in ccRCC and points toward a major role of this protein in renal cell carcinoma carcinogenesis.

Associations of TACSTD2/TROP2 and NECTIN-4/NECTIN-4 with molecular subtypes, PD-L1 expression, and FGFR3 mutational status in two advanced urothelial bladder cancer cohorts.

AIMS: Treatment options for advanced urothelial carcinoma (aUC) rapidly evolved: besides immunomodulative therapeutic options and inhibitors targeting Fibroblast growth factor receptor (FGFR) alterations, two new antibody-drug conjugates (ADC), sacituzumab govitecan (SG) and enfortumab vedotin (EV), have been approved. However, little is known about the associations of specific aUC properties and the surface target expression of TROP2 and NECTIN-4. Our aim was to characterize associations of TACSTD2/TROP2 and NECTIN-4/NECTIN-4 protein and gene expression with morphomolecular and clinicopathological characteristics of aUC in two large independent cohorts. METHODS AND RESULTS: The TCGA BLCA (n = 405) and the CCC-EMN (n = 247) cohorts were retrospectively analysed. TROP2/TACSTD2 and NECTIN-4/NECTIN-4 are highly expressed at the protein and transcript level in aUC, and their expression status did not correlate with patient survival in both cohorts. NECTIN-4/NECTIN-4 expression was higher in luminal tumours and reduced in squamous aUCs. NECTIN-4 was negative in 10.6% of samples, and 18.4% of samples had low expression (H-score <15). The TROP2 negativity rate amounted to 6.5%. TACSTD2 and NECTIN-4 expression was reduced in neuroendocrine-like and/or protein-based double-negative tumours. TROP2- and NECTIN-4-negative tumours included one sarcomatoid and four neuroendocrine aUC. FGFR3 alterations and PD-L1 expression on tumour and immune cells did not associate with TROP2 or NECTIN-4 expression. CONCLUSIONS: TACSTD2/TROP2 and NECTIN-4/NECTIN-4 are widely expressed in aUC, independent of FGFR3 alterations or PD-L1 expression, thus representing a suitable target for ADC treatment in the majority of aUC. The expression loss was associated with aggressive morphomolecular aUC subtypes, i.e. neuroendocrine(-like) and sarcomatoid aUC.

An empirical survey on the adaption of neoadjuvant chemotherapy in bladder cancer.

OBJECTIVE: To determine the adaption of neoadjuvant chemotherapy (NAC) in patients with muscle-invasive bladder cancer (MIBC) in Germany, Austria and Switzerland and especially underlying reasons for potential low adherence to guidelines. METHODS: We conducted a non-validated survey amongst 336 urologic departments in Germany, Austria and Switzerland. RedCap questionnaires were electronically distributed and included 23 items concerning the general NAC administration standards and guideline compliance in patient counselling regarding actual treatment. RESULTS: Return rate of the questionnaire was 19.1% (63/336). Although 45 departments (71.4%) claim to perform NAC as standard-of-care, only 49% of eligible patients actually receive NAC. An advanced disease stage (≥cT3) and a high tumor-volume were mentioned to support application of NAC, whereas 35% of responders worry a deterioration of patients' preoperative status due to NAC. Furthermore, 26.7% of respondents are concerned about the low extent of survival benefit. CONCLUSION: Application of NAC in eligible MIBC-patients in Germany, Austria and Switzerland remains low. Although the majority of urologic departments discusses NAC and acknowledges the need for intensified treatment in advanced disease stages, not all eligible patients will actually receive NAC before radical cystectomy.

Adipocyte Precursor-Derived NRG1 Promotes Resistance to FGFR Inhibition in Urothelial Carcinoma.

Aberrations of the fibroblast growth factor receptor (FGFR) family members are frequently observed in metastatic urothelial cancer (mUC), and blocking the FGF/FGFR signaling axis is used as a targeted therapeutic strategy for treating patients. Erdafitinib is a pan-FGFR inhibitor, which has recently been approved by the FDA for mUC with FGFR2/3 alterations. Although mUC patients show initial response to erdafitinib, acquired resistance rapidly develops. Here, we found that adipocyte precursors promoted resistance to erdafitinib in FGFR-dependent bladder and lung cancer in a paracrine manner. Moreover, neuregulin 1 (NRG1) secreted from adipocyte precursors was a mediator of erdafitinib resistance by activating human epidermal growth factor receptor 3 (ERBB3; also known as HER3) signaling, and knockdown of NRG1 in adipocyte precursors abrogated the conferred paracrine resistance. NRG1 expression was significantly downregulated in terminally differentiated adipocytes compared with their progenitors. Pharmacologic inhibition of the NRG1/HER3 axis using pertuzumab reversed erdafitinib resistance in tumor cells in vitro and prolonged survival of mice bearing bladder cancer xenografts in vivo. Remarkably, data from single-cell RNA sequencing revealed that NRG1 was enriched in platelet-derived growth factor receptor-A (PDGFRA) expressing inflammatory cancer-associated fibroblasts, which is also expressed on adipocyte precursors. Together, this work reveals a paracrine mechanism of anti-FGFR resistance in bladder cancer, and potentially other cancers, that is amenable to inhibition using available targeted therapies. SIGNIFICANCE: Acquired resistance to FGFR inhibition can be rapidly promoted by paracrine activation of the NRG1/HER3 axis mediated by adipocyte precursors and can be overcome by the combination of pertuzumab and erdafitinib treatment. See related commentary by Kolonin and Anastassiou, p. 648.

Molecular Urothelial Tumor Cell Subtypes Remain Stable During Metastatic Evolution.

Urothelial cancer (UC) care is moving toward precision oncology. For tumor biology-driven treatment of metastatic UC (mUC), molecular subtypes play a crucial role. However, it is not known whether subtypes change during metastatic evolution. To address this, we analyzed a UC progression cohort (N = 154 patients) with 138 matched primary tumors (PRIM) and synchronous or metachronous distant metastasis (MET) by immunohistochemistry, and mRNA sequencing in a subgroup of 20 matched pairs. Protein-based tumor cell subtypes and histomorphology remained stable during metastatic progression (concordance: 94%, 95% confidence interval [CI] 88-97%). In comparison, transcriptome-based molecular consensus subtypes exhibited higher heterogeneity between PRIM and MET (concordance: 45%, 95% CI 23-69%), with switches particularly occurring between luminal and stroma-rich tumors. Of note, all tumors classified as stroma rich showed luminal tumor cell differentiation. By an in-depth analysis, we found a negative correlation of luminal gene and protein expression with increasing desmoplastic stroma content, suggesting that luminal tumor cell differentiation of "stroma-rich tumors" is superimposed by gene expression signals stemming from the stromal compartment. Immunohistochemistry allows tumor cell subtyping into luminal, basal, or neuroendocrine classes that remain stable during metastatic progression. These findings expand our biological understanding of UC MET and have implications for future subtype-stratified clinical trials in patients with mUC. PATIENT SUMMARY: Urothelial carcinomas (UCs) occur in different appearances, the so-called molecular subtypes. These molecular subtypes will gain importance for the therapy of metastatic UCs in the future. We could demonstrate that the subtype remains stable during metastasis, which is highly relevant for future studies.

Pretreatment albumin is a prognostic and predictive biomarker for response to atezolizumab across solid tumors.

Objectives: Reliable predictive biomarkers for response to immune checkpoint inhibition (ICI) are lacking. Pretreatment serum albumin, a known prognostic and predictive factor in ICI-treated patients, has been proposed as a potential pharmacokinetic surrogate marker for anti-PD1/PD-L1 antibodies, as it shares a homeostatic pathway with IgG. However, this hypothesis is currently based on theoretical considerations and limited evidence from retrospective data. Therefore, we comprehensively investigated the prognostic and predictive value of pretreatment albumin and its relationship with anti-PD-L1 IgG levels. Methods: We analysed pretreatment albumin and atezolizumab serum levels and clinical response in four trials (IMvigor210, IMvigor211, IMmotion151 and OAK) of patients with metastatic lung-, renal- or urothelial cancer who received atezolizumab alone or in combination. Results: A total of 3391 patients were analysed. Correlation between serum albumin and atezolizumab levels was weak (Pearson's coefficient 0.23). We found a strong prognostic value for pretreatment serum albumin across all trials. Both atezolizumab serum levels and serum albumin were independently correlated with overall survival. Importantly, in the three randomised phase III clinical trials, the survival benefit for immunotherapy compared with the active comparator arm was limited to patients with pretreatment serum albumin > 35 g L-1. Conclusion: Our data do not support the hypothesis that albumin serves as a surrogate for atezolizumab pharmacokinetics. However, we show that albumin on its own exerts strong prognostic value for patients treated with immunotherapy. As benefit from immunotherapy was limited to patients with normal/elevated serum albumin levels, baseline albumin could potentially be used as a predictive marker for immune checkpoint inhibition.