Distinct biological types of ocular adnexal sebaceous carcinoma: HPV-driven and virus-negative tumors arise through non-overlapping molecular-genetic alterations

Purpose: Ocular adnexal (OA) sebaceous carcinoma is an aggressive malignancy of the eyelid and ocular adnexa that frequently recurs and metastasizes, and effective therapies beyond surgical excision are lacking. There remains a critical need to define the molecular-genetic drivers of the disease to understand carcinomagenesis and progression and to devise novel treatment strategies. Experimental Design: We present next generation sequencing of a targeted panel of cancer-associated genes in 42 and whole transcriptome RNA sequencing from 8 OA sebaceous carcinomas from 29 patients. Results: We delineate two potentially distinct molecular-genetic subtypes of OA sebaceous carcinoma. The first is defined by somatic mutations impacting TP53 and/or RB1 (20/29 [70%] patients, including 10 patients whose primary tumors contained co-existing TP53 and RB1 mutations) with frequent concomitant mutations affecting NOTCH genes. These tumors arise in older patients and show frequent local recurrence. The second subtype (9/29 [31%] patients) lacks mutations affecting TP53, RB1, or NOTCH family members, but in 44% (4/9) of these tumors, RNA sequencing and in situ hybridization studies confirm transcriptionally active high-risk human papillomavirus (HPV). These tumors arise in younger patients and have not shown local recurrence. Conclusions: Together, our findings establish a potential molecular-genetic framework by which to understand the development and progression of OA sebaceous carcinoma and provide key molecular-genetic insights to direct the design of novel therapeutic interventions.

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