Clear cell renal cell carcinoma (CCRCC), the most common subtype of renal cell carcinoma, is a heterogeneous cancer with variable outcomes and molecular aberrations. Further elucidation of mutational profiles and actionable mutations may improve patient outcomes in CCRCC. Somatic mutational profiling via next-generation sequencing was conducted on 30 CCRCC whole section FFPE patient samples to determine the mutational burden as compared to other solid tumor types. The sequencing failure rate for these samples was 20% (6/30). A 358-gene panel was also run on an additional 57 non-CCRCC solid tumor FFPE patient samples (81 samples in total). FASTQ files generated from Illumina's CASAVA software were submitted to the JAX Clinical Genome Analytics (CGA) data analysis pipeline to perform automated read quality assessment, alignment, and variant calling. Identified variants were then submitted for clinical curation using the JAX Clinical Knowledgebase (CKB) for actionable mutational analysis and overall mutational burden. Of the CCRCC sample set, 33% had one or more actionable mutations. This was low compared to actionable mutations in colon (16/16, 100% actionable), TNBC (18/20, 90% actionable), squamous lung (8/9, 89% actionable), and pancreatic (8/12, 67% actionable). Furthermore, the CCRCC set had a low overall mutational burden with 22 ± 6.7 nonsynonymous SNV's as compared to colon (29 ± 11), squamous lung (43 ± 17), and TNBC (31.5 ± 12). However, the pancreatic set had even lower SNV's at 12.7 ± 3.4. The number of indels was comparable across the five sets, except for colon, which averaged 6.9 ± 8.3. Significant copy number variations (CNV’s; amplification validated at greater than or equal to 6 copies) also had a wide range with squamous lung at the highest (11 ± 11), followed by TNBC (5.6 ± 5.0), and then colon (2.3 ± 3.0). Both the CCRCC and pancreatic sets had few CNV's at 0.8 ± 1.5 and 0.17 ± 0.40, respectively. Common mutations identified in the CCRCC set included EPHB6 duplications near S166, which were identified in 25% of samples. Gene specific mutations in CCRCC were also identified in VHL (54%) and SETD2 (21%). These three genes, EPHB6, VHL, and SETD2 have been previously implicated in CCRCC pathogenesis. Six variants identified in VHL were C77*, P86R, Q132fs, A149D, R177fs, and L184fs. Due to the low mutational burden and/or actionable mutations in CCRCC, even large NGS panels may not be adequate to profile somatic mutations and whole exome or whole genome may be more conducive for molecular subtyping of renal cell carcinoma.
Citation Format: Susan M. Mockus, Sara E. Patterson, Jason R. Pettus, Gregory J. Tsongalis. Actionable mutations and mutational burden in renal cell carcinoma. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 4503.