Primary adult renal sarcomas (RSs) are rare aggressive neoplasms. Clinical outcomes are extremely poor, and optimal treatment remains challenging.

To identify genomic alterations (GAs) in patients with RSs.

Comprehensive genomic profiling (CGP) was conducted on DNA/RNA extracted from formalin-fixed paraffin-embedded tissue using the FoundationOne Heme/Sarcoma assay in 13 adult, locally advanced or metastatic RSs of various histologic types.

All classes of GAs, including base substitutions, small indels, rearrangements, copy number alterations, tumor mutational burden (TMB), and microsatellite instability (MSI), were analyzed.

CGP revealed 55 GAs (4.2 per tumor), 29 of which were clinically relevant genomic alterations (CRGAs; 2.2 per tumor). At least one CRGA was detected in nine (69%) cases. High-level amplifications (more than six copies) involving 4q12 amplicon of the KIT and PDGFRA genes were identified in four (31%) cases (two undifferentiated pleomorphic sarcomas [UPSs], one sarcomatoid renal cell carcinoma, and one myxofibrosarcoma). Both UPSs also had KDR gene amplification in addition to KIT and PDGFRA. Additional CRGAs were found in CDKN2A/B (23%), NF1 (23%), and MET (8%). All RSs were MSI stable, the mean TMB was 3.5 mutations/megabase (Mb), and none (0%) featured TMB >10 mutations/Mb. Limitations include the small sample size.

RSs are characterized by diverse histology and genomic profiles including 31% of cases with 4q12 amplification harboring the KIT/PDGFRA/KDR genes. Of the tumors, 69% carry CRGAs, which could lead to potential benefit from targeted therapies; however, a low TMB also suggests that these cases are unlikely to respond to checkpoint inhibitors.

This study provides insights into molecular biology of renal sarcoma, a rare aggressive subtype of kidney tumors. We demonstrated that renal sarcomas harbor unique, recurrent, clinically relevant molecular abnormalities that provide new opportunities for targeted therapies.

European urology oncology. 2019 Apr 22 [Epub ahead of print]

Evgeny Yakirevich, Russell Madison, Eduard Fridman, Shamlal Mangray, Benedito A Carneiro, Shaolei Lu, Matthew Cooke, Gennady Bratslavsky, Jennifer Webster, Jeffrey S Ross, Siraj M Ali

Department of Pathology, Rhode Island Hospital, Providence, RI, USA; Alpert Medical School at Brown University, Providence, RI, USA. Electronic address: ., Foundation Medicine Inc., Cambridge, MA, USA., Department of Pathology, Sheba Medical Center, Tel-Aviv, Israel., Department of Pathology, Rhode Island Hospital, Providence, RI, USA; Alpert Medical School at Brown University, Providence, RI, USA., Alpert Medical School at Brown University, Providence, RI, USA; Hematology/Oncology Division, Lifespan Cancer Institute, Department of Internal Medicine, Rhode Island Hospital, Providence, RI, USA., Department of Urology, Upstate Medical University, Syracuse, NY, USA.