Background: The antibody-drug conjugate enfortumab vedotin (EV) releases a cytotoxic agent into tumor cells via binding to the membrane receptor NECTIN-4. EV has been recently approved for patients with metastatic urothelial carcinoma (mUC) without prior assessment of the tumor receptor status as ubiquitous NECTIN-4 expression is assumed. Objective: To determine the prevalence of membranous NECTIN-4 protein expression in primary tumors (PRIM) and patient-matched distant metastases (MET). Main Outcomes and Measures: Membranous NECTIN-4 protein expression was measured (H-score) by immunohistochemistry (IHC) in PRIM and corresponding MET (N=137) and in a multicenter EV-treated cohort (N=47). Progression-free survival (PFS) after initiation of EV treatment was assessed for the NECTIN-4 negative/weak (H-score 0-99) versus moderate/strong (H-score 100-300) subgroup. The specificity of the NECTIN-4 IHC staining protocol was validated by establishing CRISPR-Cas9-induced polyclonal NECTIN-4 knockouts. Results: In our cohort, membranous NECTIN-4 expression significantly decreased during metastatic spread (Wilcoxon matched pairs P<0.001, median H-score=40, interquartile range (IQR): 0-140), with 39.4% of MET lacking membranous NECTIN-4 expression. In our multicenter EV cohort, absence or weak membranous NECTIN-4 expression (34.0% of the cohort) was associated with a significantly shortened PFS on EV (Log-rank P<0.001). Conclusion: Membranous NECTIN-4 expression is frequently decreased or absent in mUC tissue. Of note, the clinical benefit of EV strongly depends on membranous NECTIN-4 expression. Thus, our results are of highest clinical relevance and argue for a critical reconsideration of the current practice and suggest that the NECTIN-4 receptor status should be determined (ideally in a metastatic/ progressive lesion) before initiation of EV.

Objectives Immune checkpoint blockade (IO) has revolutionised the treatment of metastatic renal cell carcinoma (mRCC). Early C‐reactive protein (CRP) kinetics, especially the recently introduced CRP flare‐response phenomenon, has shown promising results to predict IO efficacy in mRCC, but has only been studied in second line or later. Here, we aimed to validate the predictive value of early CRP kinetics for 1st‐line treatment of mRCC with αPD‐1 plus either αCTLA‐4 (IO+IO) or tyrosine kinase inhibitor (IO+TKI). Methods In this multicentre retrospective study, we investigated the predictive potential of early CRP kinetics during 1st‐line IO therapy. Ninety‐five patients with mRCC from six tertiary referral centres with either IO+IO (N = 59) or IO+TKI (N = 36) were included. Patients were classified as CRP flare‐responders, CRP responders or non‐CRP responders as previously described, and their oncological outcome was compared. Results Our data validate the predictive potential of early CRP kinetics in 1st‐line immunotherapy in mRCC. CRP responders, especially CRP flare‐responders, had significantly prolonged progression‐free survival (PFS) compared with non‐CRP responders (median PFS: CRP flare‐responder: 19.2 months vs. responders: 16.2 vs. non‐CRP responders: 5.6, P < 0.001). In both the IO+IO and IO+TKI subgroups, early CRP kinetics remained significantly associated with improved PFS. CRP flare‐response was also associated with long‐term response ≥ 12 months. Conclusions Early CRP kinetics appears to be a low‐cost and easy‐to‐implement on‐treatment biomarker to predict response to 1st‐line IO combination therapy. It has potential to optimise therapy monitoring and might represent a new standard of care biomarker for immunotherapy in mRCC.

2b according to the Oxford Centre for evidence-based medicine levels of evidence.

Here we describe the establishment and characterization of an AR+, PSMA+, ERG+, PTEN−/−, CHD1+/− patient-derived xenograft (PDX) model termed ‘C5’, which has been developed from a 60 years old patient suffering from castration-resistant prostate cancer (CRPC). The patient underwent radical prostatectomy, showed early tumor marker PSA recurrence and, one year after surgery, abiraterone resistance. Subcutaneous C5 tumors can be serially transplanted between mice and grow within ~90 days to 1.5–2 cm³ tumors in SCID Balb/c mice (take rate 100%), NOD-scid IL2Rgnull (NSG) mice (100%) and C57BL/6 pfp−/−/rag2−/− mice (66%). In contrast, no tumor growth is observed in female mice. C5 tumors can be cryopreserved and show the same growth characteristics in vivo afterwards. C5 tumor cells do not grow stably in vitro, neither under two- nor three-dimensional cell culture conditions. Upon serial transplantation, some C5 tumors spontaneously disseminated to distant sites with an observable trend towards higher metastatic cell loads in scid compared to NSG mice. Lung metastases could be verified by histology by means of anti-PSMA immunohistochemistry, exclusively demonstrating single disseminated tumor cells (DTCs) and micro-metastases. Upon surgical resection of the primary tumors, such pulmonary foci rarely grew out to multi-cellular metastatic colonies despite doubled overall survival span. In the brain and bone marrow, the metastatic cell load present at surgery even disappeared during the post-surgical period. We provide shallow whole genome sequencing and whole exome sequencing data of C5 tumors demonstrating the copy number aberration/ mutation status of this PCa model and proving genomic stability over several passages. Moreover, we analyzed genomic and transcriptomic alterations during metastatic progression achieved by serial transplantation. This study describes a novel PCa PDX model that enables future research on several aspects of metastatic PCa, particularly for the AR+ , ERG+ , PTEN−/− PCa subtype.

<b><i>Introduction:</i></b> The aim of this study was to test for differences in overall (OS) and progression-free survival (PFS) rates and toxicity in first-line immune checkpoint inhibition (IO) combination therapy in metastatic renal-cell carcinoma (mRCC) patients. <b><i>Methods:</i></b> Between November 2017 and April 2021, 104 patients with histologically confirmed mRCC from 6 tertiary referral centers with either IO + IO (nivolumab + ipilimumab, <i>n</i> = 68) or IO + tyrosine kinase inhibitor (TKI) (pembrolizumab + axitinib, <i>n</i> = 36) were included. Kaplan-Meier and Cox regression analyses tested for OS and PFS differences. <b><i>Results:</i></b> Of 104 mRCC patients, 68 received IO + IO (65.4%) and 36 IO + TKI (34.6%) therapy, respectively. Median age was 67 years (interquartile range: 57–70.3). Patients receiving IO + TKI were less likely to be poor risk according to the International Metastatic Renal-Cell Carcinoma Database Consortium score (16.7 vs. 30.9%) and presented with lower T-stage, compared to IO + IO treated patients. Median PFS was 9.8 months (CI: 5.3–17.6) versus 12.3 months (CI: 7.7 – not reached) for IO + IO versus IO + TKI treatment, respectively (<i>p</i> = 0.22). Median OS was not reached, survival rates at 12 months being 73.9 versus 90.0% for IO + IO versus IO + TKI patients (<i>p</i> = 0.089). In subgroup analyses of elderly patients (≥70 years, <i>n</i> = 38), IO + TKI treatment resulted in better OS rates at 12 months compared to IO + IO (91.0 vs. 57.0%; <i>p</i> = 0.042). <b><i>Conclusion:</i></b> IO + IO and IO + TKI as first-line therapies in mRCC patients were both comparable as for the oncological outcome and toxicity.