Identification of Somatic Genetic Variants in Superficial Vascular Malformations by Liquid Biopsy in a Cohort of 88 Patients from a French Hospital.

Background and objective: Superficial vascular anomalies are complex disorders characterized by abnormal vascular growth. Next-generation sequencing has recently identified somatic genetic alterations associated with these malformations, offering new insights for targeted treatments. However, tissue biopsies for genetic testing can be invasive and difficult to obtain, especially in arteriovenous malformations (AVM) with hemorrhagic risks. A liquid biopsy, a non-invasive approach, offers a promising solution by detecting genetic mutations in cell-free DNA. This pilot study aimed to evaluate the feasibility of using a liquid biopsy for the genetic analysis of patients with superficial vascular anomalies through cell-free DNA sampling. Additionally, it explored whether specific sampling sites, such as the afferent artery, nidus, and efferent vein, could enhance the sensitivity of detecting pathogenic variants in patients with AVM.

Methods: A total of 88 patients were enrolled, including 55 with AVM and 33 with lymphatic malformations. For patients with AVM, cell-free DNA samples were collected from peripheral blood, efferent veins, afferent arteries, and the AVM nidus. In patients with lymphatic malformations, cystic lymphatic fluid was collected by a direct puncture during diagnostic procedures. A molecular analysis was performed using a targeted gene panel relevant to somatic alterations in solid tumors. Pathogenic variants were validated by digital polymerase chain reaction for patients with lymphatic malformations.

Results: Pathogenic variants were identified in 23.6% of patients with AVM, predominantly in MAP2K1 and KRAS genes, with higher sensitivity near the AVM nidus. In addition, pathogenic variants were identified in 27.3% of patients with lymphatic malformations, all involving the PIK3CA gene. Despite the lower sensitivity of a cell-free DNA analysis compared with a tissue biopsy, especially in patients with AVM, the detection rate suggests the utility for a cell-free DNA analysis, particularly when a tissue biopsy is not feasible.

Conclusions: This study confirms the feasibility of using a cell-free DNA liquid biopsy for genotyping patients with superficial vascular anomalies, although a tissue biopsy remains the gold standard for comprehensive genetic profiling because of its higher sensitivity. A liquid biopsy offers a non-invasive option for molecular analysis that is useful as a preliminary or alternative approach when direct tissue sampling is not possible. Importantly, the sensitivity of cell-free DNA sampling in AVM appeared highest when obtained close to the nidus, indicating an optimal sampling location for future studies. Further research is needed to improve detection sensitivity, especially for samples taken near the nidus, to validate and strengthen these findings. Although our study focused on superficial/extra-cranial AVM, further research should assess the applicability of this approach to cerebral AVM, where a tissue biopsy is particularly risky.