Development and characterization of patient-derived salivary gland cancer organoid cultures

Objective: Three-dimensional organoid cell cultures have been established for a variety of human cancers. For most rare cancers, including salivary gland cancer (SGC), these models are lacking, despite the great unmet need to study cancer biology in these diseases. Therefore, we aimed to develop patient-derived organoid (PDO) models for different subtypes of SGC.Methods: Tumor samples of SGC patients were processed and embedded in Matrigel. Successful PDOs (expand-able > 1*106 cells) were phenotypically characterized using immunohistochemistry (IHC) and genotypically by gene fusion analysis and by targeted and whole-exome sequencing. Successfully established PDOs were subjected to small-scale drug screening.Results: Out of 37 attempts, 7 viable short-term PDOs were established (19 % success rate; 3 salivary duct car-cinoma, 3 adenoid cystic carcinoma and 1 mucoepidermoid carcinoma). Each PDO showed close phenotypical mimicry to parental tissue. Genotypic characterization revealed that in each PDO > 97.6 % of all COSMIC an-notated variants and all MYB, MYBL1 and NFIB gene rearrangements were retained. Drug screening was proven feasible in all PDOs.Conclusion: We present the first comprehensively characterized short-term SGC PDO models for three subtypes of SGC with close phenotypic and genotypic resemblance to parental tissue, which can be used for drug screening applications.