214 Abstract withdrawn

Regular and Young Investigator Award Abstracts, pp. A246

Abstract

Background Antibody-drug conjugates (ADCs) have recently moved into the clinical focus for solid carcinomas. They enable targeted delivery of cytotoxic molecules by binding to tumor surface proteins. The ADC enfortumab vedotin (EV) targets the NECTIN4 protein and was approved for patients with metastatic urothelial carcinoma (mUC). EV-treatment has a significant impact on median overall survival1 and quality of life2compared to chemotherapy. Overall response rates were 41% with a complete response only in 5% of patients.1 Response was shown to be limited by the inconsistent expression of NECTIN4 in mUC.3 4 We previously identified that NECTIN4 protein levels varied between cells and spatial domains in the same tumor, with significant decrease in progression free survival in patients with low NECTIN4 abundance. Moreover, 39% of secondary tumors lacked NECTIN4 expression.3 This means therapy success might be benefit from combining EV with a secondary therapy as recently demonstrated for EV and Pembrolizumab.5 We aim to identify novel determinants for the successful application of ADCs and to identify co-therapeutics for EV by applying spatial multi-omics to a treated mUC cohort. Methods We present data of a published3 cohort of FFPE primary and metastatic tumors from 20 EV-treated mUC patients (= 40 samples) with diverse therapy effects and NECTIN4 expression: At the RNA-level using scRNA-Seq and spatial transcriptomics, at the protein-level with Imaging Mass Cytometry (IMC) and Immunostainings, and morphology with H&E stains. Single-cell data was extracted from all omics-technologies using state-of-the-art cell segmentation algorithms. The data was fully integrated: spatially via image registration and quantitatively via harmonizing per-cell RNA counts and antibody intensities. Results Preliminary results are consistent with previous that indicate a connection between NECTIN4-expression and EV-response. We identify spatial protein and RNA signatures of NECTIN4 and other ADC-targets. These can serve as potential rescuers of treatment success in tumors with a challenging NECTIN4-landscape. Abundance and distribution of these alternative ADC-targets was as heterogenous as observed for NECTIN4. Next to target-expression, we identified additional determinants of treatment outcome linked to the cellular makeup of the tumors and the cell-states and environments therein. Conclusions Characterization of the spatial landscape of ADC-targets is vital to personalize therapies for patients. It can boost responses with co-therapies and help avoid side-effects from treatments with little-to-no chance of success. Spatial multi-omics characterization has the potential to accelerate the development of these therapies and identify new biomarkers to predict ADC-response - not only in mUC. References Powles T, Rosenberg JE, Sonpavde GP, et al. Enfortumab vedotin in previously treated advanced urothelial carcinoma. N Engl J Med 2021;384:1125–1135. Rosenberg JE, Mamtani R, Sonpavde GP, et al. Health-related quality of life in patients with previously treated advanced urothelial carcinoma from EV-301: a phase 3 trial of enfortumab vedotin versus chemotherapy. European Urology 2024;85:574–585. Klümper N, Ralser DJ, Ellinger J, et al. Membranous NECTIN-4 expression frequently decreases during metastatic spread of urothelial carcinoma and is associated with enfortumab vedotin resistance. Clinical Cancer Research 2023;29:1496–1505. Chu CE, Sjöström M, Egusa EA, et al. Heterogeneity in NECTIN4 expression across molecular subtypes of urothelial cancer mediates sensitivity to enfortumab vedotin. Clinical Cancer Research 2021;27:5123–5130. Powles T, Valderrama BP, Gupta S, et al Enfortumab vedotin and pembrolizumab in untreated advanced urothelial cancer. N Engl J Med 2024;390:875–888.

Authors 6

1. Benedikt S. Nilges
   Affiliation as printed

   OMAPiX GmbH, Kaarst, CA, Germany

2. Paul Kießling Aachen

   Universitätsklinikum Aachen · RWTH Aachen University

   Affiliation as printed

   Hospital RWTH Aachen, Aachen, NRW, Germany

3. Mar MMuniz Moreno
   Affiliation as printed

   OMAPiX Inc., Stanford, CA, USA

4. Niklas Klümper

   University Hospital Bonn

   Affiliation as printed

   University Medical Center Bonn (UKB), Bonn, NRW, Germany

5. Markus Eckstein

   Friedrich-Alexander-Universität Erlangen-Nürnberg

   Affiliation as printed

   Friedrich-Alexander-Universitat Erlangen-Nurnberg, Erlangen, Bavaria, Germany

6. Christoph Kuppe Aachen

   Universitätsklinikum Aachen · RWTH Aachen University

   Affiliation as printed

   University Hospital RWTH, Aachen, NRW, Germany