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FDA approvedFDA approved. Stage 4 of 4 (Authorized)

FDA Expands Instylla's Embrace Hydrogel Embolic Approval to Peripheral Arterial Bleeds

A panel-track PMA supplement adds bleeding in vessels up to 6 mm to the liquid embolic's original hypervascular tumor indication, based on the 130-patient HALT study.

By News DeskOctober 29, 20262 min read
An empty catheterization lab with a procedure table, overhead monitor, C-arm imaging system and supply carts
A catheterization laboratory in Germany of the kind used for embolization procedures. Embrace HES is not pictured. Echa24161, CC BY-SA 4.0, via Wikimedia Commons · CC BY-SA 4.0
FDA approvedPMA, high-risk deviceFDA approved. Stage 4 of 4 (Authorized)

The FDA approved this high-risk device through premarket approval (PMA), after reviewing clinical evidence of safety and effectiveness.

Key points

  • The FDA approved PMA supplement P250003/S008 on October 23, 2026, adding embolization of peripheral arterial bleeds in vessels of 6 mm or less to the Embrace Hydrogel Embolic System's label.
  • Instylla said the HALT study, a single-arm trial of 130 patients at 22 US sites, met both primary endpoints; the results are company-reported and listed as data on file.
  • Embrace HES was first approved in August 2025 for embolizing hypervascular tumors in peripheral arteries of 5 mm or less.

The US Food and Drug Administration has approved an expanded indication for Instylla's Embrace Hydrogel Embolic System (HES), adding the embolization of peripheral arterial bleeds in vessels 6 millimetres or smaller, the Burlington, Massachusetts, company announced on October 29.

The FDA's premarket approval database lists the change as supplement S008 to PMA P250003, a panel-track supplement received on April 28, 2026, and approved on October 23. The approval order states that the device is now indicated for embolization of hypervascular tumors in peripheral arteries of 5 mm or less and peripheral arterial bleeds in vessels of 6 mm or less. The supplement record cites clinical trial NCT05364502.

The original PMA was approved on August 5, 2025, for the tumor indication alone. Embolization is a catheter-based procedure in which material is delivered into a blood vessel to block flow, for example to stop bleeding or cut the supply to a tumor.

The HALT study

Instylla said the approval was based on the HALT study, a prospective, multicenter, single-arm trial that enrolled 130 patients with peripheral arterial bleeds at 22 US sites. The ClinicalTrials.gov record for NCT05364502 lists Instylla as sponsor and an enrollment of 130.

According to the company, Embrace HES met both prespecified primary endpoints, with 100% freedom from major adverse events and 90.0% clinical success, defined as no rebleeding from the target lesion, through 30 days. The release cites these results as data on file; they have not been published in a peer-reviewed journal.

"When treating an arterial bleed, you need an embolic solution that can reach the source of bleeding while providing precise control," said Suvranu Ganguli, MD, chief of interventional radiology at Boston Medical Center and principal investigator of the HALT study, in the company's release. "Its novel design also allows you to maintain microcatheter access after embolization, unlike many currently available liquid embolics."

How the material works

The company describes Embrace HES as a water-based polyethylene glycol hydrogel that forms inside the vessel. According to Instylla, the hydrogel is non-adhesive, so it cannot trap the delivery catheter; it works independently of the patient's clotting; and it contains no DMSO, a solvent used in some other liquid embolics, or components that obscure CT or MRI images. The company said the hydrogel liquefies through hydrolysis over about 11 months.

The release notes that coils, a conventional embolic, depend on the patient's own clotting and can be less effective in people whose blood does not clot normally.

"With approvals now in both interventional oncology and peripheral hemostasis, we're redefining what's possible in interventional care and building a transformative platform for the many vascular conditions still ahead," said Sean Boyle, Instylla's chief executive.

Instylla, a privately held company founded in 2017 by Incept LLC, said Embrace HES is commercially available in the US. It did not disclose pricing.

Sources

  1. Instylla's Embrace Hydrogel Embolic System Receives FDA Approval for Peripheral Arterial Bleeds, Instylla press release (PR Newswire), October 29, 2026
  2. Premarket Approval P250003/S008: Embrace Hydrogel Embolic System, US Food and Drug Administration, October 23, 2026
  3. Premarket Approval P250003: Embrace Hydrogel Embolic System, US Food and Drug Administration, August 5, 2025
  4. (HALT) Embrace Hydrogel Embolic System (HES) Study of Embolization in Peripheral Arterial Bleeds, NCT05364502, ClinicalTrials.gov, November 1, 2026