Mutational patterns in a large cohort of parathyroid carcinomas.

Abstract

Purpose: A lack of targeted therapies make parathyroid carcinoma, a diagnostically challenging malignancy, difficult to treat. The rarity of this tumor type necessitates international collaboration to collect a sizable sample set for study. Prior studies have revealed the importance of driver mutations in the CDC73 gene and identified several putative drivers/aberrant pathways including PI3K/mTOR activation and CCND1 (cyclin D1) amplification. In this study, we sought to better understand the prevalence of putative oncogenic drivers in parathyroid carcinoma.

Methods: We subjected an expanded cohort of 71 sporadic parathyroid carcinomas, fulfilling stringent WHO criteria, to next-generation DNA sequencing on a custom 16-gene targeted panel.

Results: One or more variant was detected in 44 tumors (62%) and 27 (38%) had no detectable variant. Consistent with earlier studies, we detected loss-of-function CDC73 mutations in 44% (31/70) of evaluable patients, including germline pathogenic variants in 9 patients (36 patients evaluable for somatic status as matched normal available). Notably, mutations in the PI3K/AKT/mTOR pathway were seen in 12.9% (9/70) of evaluable patients, providing further evidence of this as a key therapeutically actionable pathway in parathyroid carcinoma. Correlating genomic and clinical features revealed that patients harboring CDC73 mutations are more likely suffer from life threatening recurrent/metastatic parathyroid carcinoma (P = 0.024) than those without CDC73 variants.

Conclusions: This genomic characterization of a large parathyroid carcinoma cohort improves understanding of the genomic underpinnings of this rare malignancy, provides novel evidence for genotype-phenotype correlation with recurrent/metastatic disease, and may help to provide a rational basis for individualized treatments.