Detailed genomic characterization identifies high heterogeneity and histotype-specific genomic profiles in adrenocortical carcinomas

Molecular characterization of adrenocortical carcinoma has been recently established, but the correlation between molecular profiles and clinical and pathological characteristics is still poorly defined with no data available about genetic heterogeneity along disease progression. In this scenario, a detailed molecular profile was correlated with clinical and pathological characteristics in adrenocortical carcinoma patients to identify potentially novel biomarkers. Targeted next-generation sequencing and copy number variation analyses for 18 most frequently altered genes in adrenocortical carcinoma were assessed on 62 adult cases (including 10 with matched primary and metastatic/recurrence samples) and results correlated with major clinical and pathological characteristics of tumors. A total of 433 somatic deleterious genetic alterations (328 gene mutations and 105 copy number variations) were identified in 57/62 cases, five resulted wild type for all genes tested. TERT, CDK4, ZNRF3, and RB1 were altered in more than 30% of cases. Among histological variants genotypes were significantly different. Lowest mutation burden was found in the oncocytic type (p = 0.006), whereas the highest with a prevalence of RB1 (p = 0.001) and CDK4 (p = 0.002) was found in the conventional and myxoid ones, respectively. None of the 10 cases with matched samples showed a stable genotype along tumor progression, although allelic frequencies or percentages of altered nuclei at fluorescence in situ hybridization were in most cases similar among different tumor samples for genes that were stable along tumor progression. Among individual genes, an altered p53/Rb1 pathway was the strongest adverse molecular signature, being associated with high Ki-67 index, high tumor stage, aggressive disease status, and shorter disease-free survival. The genomic signature in adrenocortical carcinoma is changing along tumor progression and is associated with specific clinical and pathological features, including histological variant and prognosis.