Molecular Analysis of Salivary and Lacrimal Adenoid Cystic Carcinoma

Adenoid cystic carcinoma (ACC) of head and neck origin is associated with slow but relentless progression and systemic metastasis, resulting in poor long-term survival rates. ACC does not respond to conventional chemotherapy. Determination of molecular drivers may provide a rational basis for personalized therapy. Herein, we investigate the clinical and detailed molecular genomic features of a cohort of patients treated in Ireland and correlate the site of origin, molecular features, and outcomes. Clinical and genomic landscapes of all patients diagnosed with ACC over a twenty-year period (2002-2022) in a single unit in Ireland were examined and analyzed using fluorescence in situ hybridization, DNA sequencing, and bioinformatic analysis. Fourteen patients were included for analysis. Eleven patients had primary salivary gland ACC and three primary lacrimal gland ACC; 76.9% of the analyzed tumors displayed evidence of NFIB-MYB rearrangement at the 6q23.3 locus; 35% had mutations in NOTCH pathway genes; 7% of patients had a NOTCH1 mutation, 14.3% NOTCH2 mutation, and 14.3% NOTCH3 mutation. The presence of epigenetic modifications in ACC patients significantly correlated with worse overall survival. Our study identifies genetic mutations and signaling pathways that drive ACC pathogenesis, representing potential molecular and therapeutic targets.