(1033) Identifying Treatment Options for Pediatric Vascular Anomalies Using Commercially Available Next Generation Sequencing

Introduction: Vascular anomalies (VA) have a wide range of presentations. They can be deforming, have a significant impact on quality of life, and in some cases be fatal. Treatment was traditionally limited to surgery or ablative procedures such as laser or sclerotherapy, with few medical options. Ongoing work has demonstrated that somatic genetic mutations are the basis of most sporadic VA. For example, most lymphatic malformations and many venous malformations are caused by activating mutations in PIK3CA, a gene encoding a subunit of PI3K. This recognition and subsequent investigations led to recent FDA approval of alpelisib - a targeted inhibitor of PI3K - for the treatment of PIK3CA Overgrowth Spectrum (PROS). Despite the growing importance of genetic testing in the management of VA, performing testing can be logistically challenging. We describe our experience using a commercially available cancer genomic sequencing panel to analyze tissue specimens from pediatric patients with VA.

Methods: Retrospective chart review examining genetic testing results, clinical diagnoses, and treatment of patients who had genetic testing of biopsy tissue samples performed using the Tempus xT 648 gene panel.

Results: In total, 29 patients ranging in age from 2-22 years old had tissue or blood sent for genetic sequencing. The most common clinical diagnoses were somatic overgrowth (21%), lymphatic malformations (17%) and capillary malformations (14%). Of the total, 34% (10/29) of patients had PIK3CA mutations and of these 60% were associated with PROS and 40% (4/10) were started on alpelisib. Most patients 72%, (21/29) had tissue biopsy performed while under anesthesia for other procedures.

Conclusions: Use of a commercially available genomic sequencing panel can be an efficient option to obtain genetic diagnoses to guide management of children with VA.