Sarcomatoid renal cell carcinoma (sRCC) represents an aggressive group of renal epithelial tumors characterized by histopathological features of epithelial–mesenchymal plasticity (EMT) and prominent metastatic behavior. These malignancies are extremely challenging in the clinic, as they fail to respond to the standard-of- care therapeutic regimens for RCC. Furthermore, in spite of the remarkable advances in cancer genomics, there are still no reliable tools or biomarkers to predict the clinical course of the disease, particularly in the context of modern therapeutic interventions. Objectives. The long-term goal of this project is to identify the genomic and molecular drivers of malignant progression in sRCC, focusing on the role of EMT in clonal evolution, in the acquisition of metastatic potential and as a mechanism of adaptation to therapy. This will lead to the identification of context-specific vulnerabilities dictated by the specific genomic and molecular landscapes that characterize this aggressive subset of kidney cancer. Rationale and Hypothesis. Preliminary studies showing the emergence of specific patterns of chromosomal alterations led us to the hypothesis that the acquisition of chromosomal instability (CIN) during tumor evolution favors the selection of clones endowed with high cellular plasticity and prominent metastatic potential. Specific Aims. In the first aim we will provide a detailed spatial and temporal annotation of epithelial and mesenchymal population dynamics during malignant progression and in response to pharmacological interventions. The second aim will define the genomic and transcriptomic landscape of the malignant subpopulation and the interplay between these cellular compartments and the components of the TME. In the third aim we will identify context-specific vulnerabilities, defining the genetic dependencies of epithelial and mesenchymal cells. Significance. The approach will provide fundamental information about clonal dynamics, tumor–host interactions at a single-cell resolution, and tumor evolution in RCC, substantially improving our understanding of the genetic and molecular bases of the disease. Translational relevance. A detailed understanding of the genetic and molecular events driving malignant cell plasticity and the evolution to sRCC will provide the framework to predict the behavior of this heterogeneous group of tumors. Furthermore, the functional genomic approach will uncover context-specific vulnerabilities and provide novel drug targets in a disease class in urgent need of effective treatments. Innovation. The project is innovative from a conceptual and technological standpoint. Targeting cancer-specific weaknesses emerging in the context of cell plasticity, increased tumor heterogeneity, and clonal diversification is a promising approach tailored to the genetic and functional hallmarks of the disease. The technological tools and approaches are unique and highly innovative. The introduction of a li...