Instylla Gains U.S. FDA Premarket Approval for Embrace™ Hydrogel Embolic System

First and Only Liquid Embolic Approved for Hypervascular Tumor Embolization Supported by a Prospective, Randomized, Controlled, Clinical Trial

BEDFORD, Mass., Aug. 7, 2025 /PRNewswire/ -- Instylla, Inc., a privately held company developing novel resorbable embolics for peripheral vascular embolization, announced premarket approval (PMA) from the U.S. Food and Drug Administration (FDA) for the company's flagship product Embrace™ Hydrogel Embolic System. Embrace HES has been approved for the embolization of hypervascular tumors in peripheral arteries ≤ 5mm. 

Hypervascular tumors (HVTs), which commonly occur in the liver, kidney, bone, and other organs, are characterized by an abnormal increase in blood vessels and are often associated with poor survival outcomes¹. Their high vascularity can make surgical removal difficult due to the elevated risk of bleeding. For patients with limited progressive disease or for local tumor control, transcatheter arterial embolization (TAE) and transarterial chemoembolization (cTACE) are established and widely used treatment options.

Embrace HES consists of two low-viscosity aqueous liquid precursors that interact to crosslink intravascularly when simultaneously injected into blood vessels during the embolization procedure to form a soft, polyethylene glycol (PEG) hydrogel. This liquid embolic is designed to deeply penetrate the tumor vascular bed², crosslink, and stop blood flow.

Premarket approval for Embrace HES was granted based on results from a prospective, randomized, multicenter pivotal study that evaluated its safety and effectiveness for the embolization of hypervascular tumors compared to the standard of care, SOC (TAE or cTACE). The study enrolled 150 patients with hypervascular tumors across 22 global institutions and randomized them 2:1 to receive either Embrace HES or SOC treatment³. Embrace HES met both primary safety and effectiveness endpoints, demonstrating 88.6% technical success as confirmed by an independent core lab and 99% freedom from major adverse events, as adjudicated by a Clinical Events Committee. Importantly, no adverse events were classified as device-related only.

"The pivotal trial was designed to evaluate the Embrace HES system in patients with hypervascular tumors," said Dr. Nadine Abi-Jaoudeh, Chief of Interventional Radiology at the University of California, Irvine, and National Principal Investigator of the study. "Embrace HES is the first liquid embolic approved specifically for this indication, with a unique design that enables deep penetration into vessels as small as 10 microns. Delivered as two liquid precursors that polymerize in situ to minimize non-target embolization, the cohesive embolic also avoids catheter entrapment. Additionally, Embrace HES does not have any imaging artifacts, allowing us to assess follow-up imaging with confidence. The trial met both its safety and efficacy endpoints, and I am excited to have this wonderful new tool in the IR repertoire." 

"We are incredibly proud to receive FDA approval for Embrace HES, offering a transformational embolic platform technology solving critical unmet needs for cancer patients with hypervascular tumors," said Sean Boyle, CEO, Instylla, Inc. "This milestone represents years of innovation and dedication of our team to advancing interventional oncology. More importantly, it brings new hope to patients and their families facing the challenges of cancer. We are motivated and committed to delivering technically advanced, clinically impactful solutions that empower interventional radiologists and expand therapeutic options across a broad range of vascular conditions."

About Embrace Hydrogel Embolic System:
Embrace HES is indicated to embolize hypervascular tumors in peripheral arteries ≤ 5 mm. Embrace HES consists of two injectable liquid precursors that crosslink when simultaneously delivered into blood vessels, forming a soft hydrogel that fills the vessel lumens during embolization. Embrace HES embolization uses no solvents, does not need sizing to the vessel diameter, and eliminates the possibility of catheter entrapment. Its main components are water and polyethylene glycol (PEG).   

About Instylla:
Instylla, Inc. is a privately held company based in Bedford, MA, focused on developing novel resorbable embolic agents to advance interventional radiology, with initial clinical applications in interventional oncology and peripheral hemostasis. Instylla was founded in 2017 by Incept LLC and is funded by several leading venture capital groups.  

To learn more, please visit https://www.instylla.com/

¹ Hotta, Naoki & Ayada, Minoru & Okumura, Akihiko & Ishikawa, Tetsuya & Sato, Ken & Oohashi, Tomohiko & Hijikata, Yasutaka & Kakumu, Shinichi. (2009). Hepatocellular Carcinoma 11 and a Half Years after the Resolution of Chronic Hepatitis C Virus Infection Successfully Treated with Interferon. Case reports in gastroenterology. 3. 175-181. 10.1159/000225244.

² Ganguli S, Lareau R, Jarrett T, Soulen MC, A Water-based Liquid Embolic: Evaluation of Safety and Efficacy in a Rabbit Kidney Model, Journal of Vascular and Interventional Radiology (2021)

³ Data on file

SOURCE Instylla, Inc.