8q Gain Has No Additional Predictive Value in SF3B1MUT Uveal Melanoma but Is Predictive for a Worse Prognosis in Patients with BAP1MUT Uveal Melanoma.

ABSTRACT

Purpose: Gain of chromosome 8q has been associated with poor prognosis in uveal melanoma (UM), and an increase in the absolute number of 8q-copies correlated with an even shorter survival. Splicing factor 3b subunit 1 (SF3B1)-mutated (SF3B1MUT) tumors display structural chromosomal anomalies and frequently show a partial gain of chromosome 8qter. A recent subset of SF3B1MUT UM with early-onset metastases has been identified, prompting the investigation of the relationship between survival, 8q gain, and SF3B1MUT UM. Design: Retrospective cohort study. Subjects: Patients diagnosed with UM who underwent enucleation or received a biopsy at the Erasmus MC Cancer Institute or the Rotterdam Eye Hospital, The Netherlands were included. Methods: Fifty-nine patients with SF3B1MUT tumors and 211 patients with BRCA1 associated protein 1 (BAP1)-mutated (BAP1MUT) tumors were included in this study. Copy number status and gene expression were assessed using either a single nucleotide polymorphism array, fluorescence in situ hybridization, and karyotyping, or a combination of these techniques. Disease-free survival was determined and a cut-off of 60 months was used to define early-onset metastatic disease. Main Outcome Measures: Disease-free survival. Results: Forty-eight patients with SF3B1MUT UM (81%) had chromosome 8q gain (3 copies, 78%; 4 copies, 22%). Kaplan-Meier analysis of SF3B1MUT UM did not indicate a difference in survival in patients with or without gain of 8q (P = 0.99). Furthermore, the number of 8q copies was not associated with survival when comparing early (P = 0.97) versus late (P = 0.23) metastases group. In contrast, the presence of 8q gain (86%) was correlated with a decreased survival in BAP1MUT UM (P = 0.013). Conclusions: We did not find a correlation between 8q gain and early-onset metastasis in SF3B1MUT tumors. Gain of 8q has no additional predictive value in SF3B1MUT tumors. In contrast, 8q gain is predictive of a worse prognosis in patients with BAP1MUT tumors. Thus, gain of chromosome 8q has additional predictive value for BAP1MUT tumors, but not for SF3B1MUT tumors. Financial Disclosures The author(s) have no proprietary or commercial interest in any materials discussed in this article.