Sarcomatoid Dedifferentiation in Renal Cell Carcinoma: From Novel Molecular Insights to New Clinical Opportunities.

Sarcomatoid features in renal cell carcinoma (RCC) have long been associated with dismal prognosis and poor response to therapy, while biological mechanisms underpinning sarcomatoid dedifferentiation remained obscure. Several efforts have been conducted to break down the molecular profile of sarcomatoid RCC and investigate different targeted therapeutic approaches. Mutations enriched for in sarcomatoid RCC involve, notably, TP53, BAP1, cell cycle, and chromatin-remodeling genes. The immunological landscape of these tumors is also gradually being uncovered, showing frequent expression of programmed cell death ligand-1 (PD-L1) and high levels of tumor-infiltrating lymphocytes. These features may be major determinants for the activity of immune checkpoint inhibitors in this population, which has been confirmed by retrospective studies and subgroup analyses of large randomized phase 3 trials. Combinations based on PD-1/PD-L1 inhibition have demonstrated response rates and complete responses in >50% and >10% of patients in the first-line metastatic setting, respectively, with median overall survival exceeding two years. This remarkable improvement in outcomes effectively establishes immune checkpoint inhibitor combinations as a new standard of care in patients with sarcomatoid RCC. New research fields, including epigenetic regulations and tumor-microenvironment interactions, may further sharpen understanding of sarcomatoid RCC and advance therapeutic developments.

Cancers. 2019 Dec 31*** epublish ***

Véronique Debien, Jonathan Thouvenin, Véronique Lindner, Philippe Barthélémy, Hervé Lang, Ronan Flippot, Gabriel G Malouf

Department of Oncology, Institut de Cancérologie de Strasbourg, Hôpitaux Universitaires de Strasbourg, Université de Strasbourg, 67200 Strasbourg, France., Department of Pathology, Centre Hospitalier Universitaire Régional de Strasbourg, 67200 Strasbourg, France., Department of Cancer and Functional Genomics, Institute of Genetics and Molecular and Cellular Biology, CNRS/INSERM/UNISTRA, 67400 Illkirch, France., Department of Urology, Centre Hospitalier Universitaire Régional de Strasbourg, 67000 Strasbourg, France., Department of Cancer Medicine, Gustave Roussy, 94800 Villejuif, France.