Circulating tumor DNA accelerates diagnosis and treatment guidance for metastatic uveal melanoma with hepatic lesions not amenable to biopsy.

Uveal melanoma is a common intraocular tumor in which up to 50% of patients develop metastasis. Uveal melanoma often presents asymptomatically and is usually diagnosed by clinical examination and imaging, as tissue biopsy is not feasible. Recently, analysis of circulating tumor DNA has enabled diagnosis and mutation analysis in such tumors where tissue sampling cannot be performed. In our case study report, we demonstrate the use of the Caris Assure Assay for the diagnosis of metastatic uveal melanoma in a patient where tissue biopsy was not feasible. Plasma analysis identified a pathogenic SPEN variant and human leukocyte antigen (HLA) genotype (HLA-A*02:17 and HLA-A*02:01 alleles), conferring therapeutic eligibility for tebentafusp, and molecular evidence supportive of metastatic uveal melanoma, enabling initiation of appropriate systemic therapy before additional tissue sampling. Subsequent tissue biopsy from the liver (56 days after liquid biopsy) confirmed canonical GNAQ and SF3B1 driver mutations, reinforcing the diagnosis and clarifying the molecular underpinnings of the metastatic lesion itself. While the liquid biopsy and ablation of one of the lesions confirmed the diagnosis, the liquid biopsy was a key first step that provided a comprehensive diagnostic and prognostic picture without the need for an invasive procedure. This case highlights how integrating liquid biopsy into the diagnostic pathway for uveal melanoma can lead to earlier, more informed treatment decisions.