FDA Expands Indication for Instylla’s Embrace HES to Treat Peripheral Arterial Bleeds

The US Food and Drug Administration has granted an expanded indication for Instylla’s Embrace hydrogel embolic system to treat peripheral arterial bleeds in vessels measuring up to 6mm. The regulatory decision follows the device’s original premarket approval, which was granted in August 2025 for embolising hypervascular tumours in peripheral arteries measuring up to 5mm.

Clinical Trial Design and Findings

Data supporting the expanded clearance were obtained from the prospective, single-arm HALT clinical trial conducted across 22 US centres. The study involved 130 patients presenting with peripheral arterial haemorrhage. According to the reported findings, the trial achieved both of its designated primary endpoints.

• Evaluated over a 30-day period, the device demonstrated 100% freedom from major adverse events.
• The trial achieved a clinical success rate of 90%, defined by researchers as the absence of further bleeding from targeted lesions.

Instylla CEO Sean Boyle commented on the announcement by stating that patients facing complex vascular conditions need more options, and that the hydrogel system was built to deliver that versatility.

Device Mechanism and Clinical Context

The product is a water-based polyethene glycol hydrogel that is commercially available in the United States. It solidifies inside blood vessels to establish rapid and lasting occlusions before breaking down through hydrolysis over approximately 11 months.

The formulation is non-adhesive, which prevents catheter entrapment, and it operates independently of native coagulation pathways. Additionally, the system contains no dimethyl sulfoxide and incorporates no elements that distort computed tomography or magnetic resonance imaging scans. It is designed to target acute vascular trauma as well as non-traumatic sources, including solid-organ bleeds, tumours, and non-variceal upper gastrointestinal bleeding where conventional endoscopy fails.

While traditional transcatheter arterial embolisation records success rates between 81% and 100% in unstable pelvic fractures, traditional mechanical solutions such as coils remain reliant on native clotting mechanisms. Consequently, standard mechanical devices can lose effectiveness in patients who suffer from coagulopathy, highlighting the distinct mechanism of non-coagulation-dependent alternatives.