Multicenter Randomized Trial Evaluating the Safety and Effectiveness of the Instylla Hydrogel Embolic System for...

To report the results of the randomized (2:1) pivotal study evaluating the safety and effectiveness of the Instylla Embrace Hydrogel Embolic System (HES), consisting of 2 low-viscosity, liquid precursors that form a biocompatible crosslinked polyethylene glycol hydrogel, compared with standard of care (SOC) in the embolization of hypervascular tumors (HVTs).

This prospective, multicenter, randomized, noninferiority study of adults with malignant and benign HVT had dual primary endpoints of safety and effectiveness. Safety was freedom of major adverse events (MAEs) through 30 days including death, nontarget embolization, unintended tissue ischemia, pulmonary embolism, vascular injury requiring intervention, renal or hepatic failure, abscess in target organ, or toxic/allergic reaction to HES. Effectiveness (technical success) was delivery of the embolic agent to the tumor feeding vessel(s), with stasis of flow assessed by an independent blinded imaging core laboratory. Additional endpoints were assessed through 180 days. Adverse events and imaging were independently adjudicated.

There were 150 subjects (56% men and 44% women), with mean age of 65.4 years (SD ± 12.9) and tumors of ≤ 8 cm, recruited from 22 international centers. HES-treated subjects (102) had 118 tumors and 148 vessels treated, and SOC-treated subjects (48) had 56 tumors and 72 vessels treated. Both primary endpoints were successfully achieved. Freedom from MAE was 99% (P < .001), and technical success was achieved in 88.6% of HES and 77.3% of SOC (P = .001).

This randomized study of a peripheral liquid embolic demonstrated that the Instylla Embrace HES met its primary endpoints in the treatment of HVTs.