A Phase I First in Human Study of Embrace™ a Polyethylene Glycol Based Liquid Embolic in the Embolization of Malignant and Benign Hypervascular Tumors

An In Situ Curing, Shear-Responsive Biomaterial Designed for Durable Embolization of Microvasculature

Endovascular embolization is a minimally-invasive technique whereby blood vessels supplying pathological structures are selectively occluded with various embolic agents. In many scenarios, it is desirable for the embolic to distally penetrate to the level of the microvasculature, which maximizes devascularization. Existing agents exhibit inconsistent distal penetration and have other limitations including tendency for proximal reflux, patient pain during infusion, lack of fluoroscopic radiopacity, potential for catheter adhesion, susceptibility to recanalization, and other usability challenges. NeoCast is an in situ curing, solvent-free, non-adhesive biomaterial composed of polydimethylsiloxane, bismuth trioxide, and fumed silica that possesses shear-responsive properties enabling manual injectability through commercially-available microcatheters with large and small diameter lumens. Here, embolization performance with and without flow arrest, in both arterial and venous preclinical anatomies is reported. NeoCast reproducibly achieves a rate of distal penetration with microvascular occlusion that is superior to existing agents, exhibits excellent fluoroscopic visibility, and provides durable occlusion. There is mild inflammation when NeoCast is infused into blood vessels and absence of neurotoxicity when implanted directly into brain tissue. The engineered NeoCast material is poised to become a next-generation, liquid embolic agent for applications in which distal microvascular occlusion is desired.

Self-assembling chemodrug fiber-hydrogel for transarterial chemoembolization and radiotherapy-enhanced antitumor immunity

Hydrogel, as a promising embolic material for hepatocellular carcinoma (HCC), may fully embolize both major vessels and peripheral microvessels. A self-assembling hydrogel composed of chemotherapeutic drugs offers significant clinical benefits without carrier introduction. Herein, we developed a sustained drug-releasing complex hydrogel (RKT@gel), which was fabricated by the self-assembly of raltitrexed chemotherapeutic drugs (R@gel), along with the incorporation of kaempferol and tantalum nanoparticles (Ta NPs). Kaempferol enhances the mechanical strength of R@gel and inhibits hypoxia-induced angiogenesis post-embolization, improving embolization effectiveness. In addition to enabling X-ray-guided transarterial chemoembolization (TACE), Ta NPs enhance radiation sensitivity. These synergistic effects of RKT@gel not only significantly induce immunogenic cell death, thereby enhancing the activation of dendritic cells, but also activate major histocompatibility complex class I (MHC-I)-mediated antitumor immune recognition and cytotoxicity. In vivo, RKT@gel achieves enhanced tumor deposition and sustained drug release, effectively suppressing tumor progression. Additionally, when combined with radiotherapy, RKT@gel achieves efficient antitumor immunoactivation. Overall, this versatile composite hydrogel not only achieves effective embolization therapy but also substantially triggers antitumor immune responses with good biocompatibility. This multifunctional design provides a TACE-based multidisciplinary strategy for HCC.

Comparison of Liquid with Particle Embolics in a Translational Rat Model of Hepatocellular Carcinoma: Histologic and Radiographic Responses

PURPOSE

To compare the effectiveness of transarterial embolization (TAE) using a liquid embolic (LE) with that of TAE using a particle embolic (PE) based on radiographic and histologic responses in a translational rat model of hepatocellular carcinoma (HCC).

MATERIALS AND METHODS

HCC was induced in Wistar rats using diethylnitrosamine. Tumor response was determined through Response Evaluation Criteria in Solid Tumors applied to T2-weighted magnetic resonance (MR) imaging scans. Tumor necrosis and hypoxia were assessed through hematoxylin and eosin and pimonidazole staining, respectively. Statistical analyses were performed using chi-square tests, Kaplan-Meier estimates, logistic regression, and 1-way analysis of variance, with significance set at P < .05.

RESULTS

Twenty-nine rats were randomized to TAE with LE (n = 13), PE (n = 13), or sham (n = 3). LE TAE demonstrated a significantly higher objective response rate (83%) compared with PE TAE (28%; χ2 = 11.25; P = .0008). Complete responses were observed in 50% of the LE-treated tumors versus 10% in the PE-treated group. LE TAE prolonged local progression-free survival (hazard ratio, 0.31; P = .032). Histologic analysis of an additional 16 rats randomized to TAE with LE (n = 7), PE (n = 6), or sham (n = 3) showed greater necrosis in LE-treated tumors compared to PE-treated tumors. LE induced a significantly greater reduction in viable tumor tissue (P = .009) and proportionally larger necrotic and necrotic + hypoxic tissue areas compared with PE (P = .003).

CONCLUSIONS

LE significantly enhanced the therapeutic effectiveness of TAE in a rat model of HCC compared with PE. These results highlight the potential of LEs to improve ischemia and necrosis, thereby offering a promising option for improving the effectiveness of embolization for HCC treatment.

Ultrafine fiber-mediated transvascular interventional photothermal therapy using indocyanine green for precision embolization treatment

Photothermal treatment has attracted immense interest as a promising approach for biomedical applications such as cancer ablation, yet its effectiveness is often limited by insufficient laser penetration and challenges in achieving efficient targeting of photothermal agents. Here we developed a transvascular interventional photothermal therapy (Ti-PTT), which employed a small-sized microcatheter (outer diameter: 0.60 mm, 1.8 Fr) equipped with an ultrafine optical fiber (diameter: 100 μm) capable of simultaneously delivering photothermal agents while performing 808 nm laser irradiation via an endovascular route. Specifically, we employed two types of indocyanine green (ICG)-based photothermal agents, i.e. ICG solution serving as a purely photothermal agent and ICG-ethiodized oil (ICG-EO) emulsion acting as a radiopaque photothermal embolic agent. Using the customized microcatheter with the ICG solution, both proximal and distal embolization were able to be performed in a rat liver model. Compared to the ICG solution, the ICG-EO emulsion dramatically enhanced the ICG retention time, enabling a photothermally triggered precision vascular blockade to induce local embolization of large tissue volumes in a rat kidney model with an unfavorable ICG leakage rate. The Ti-PTT paves the way to broadening the potential applications of photothermal therapy through combination with clinical intervention-based approaches.

Hydrogels in the clinic: An update

Hydrogels have been used in the clinic since the late 1980s with broad applications in drug delivery, cosmetics, tissue regeneration, among many other areas. The past three decades have witnessed rapid advances in the fields of polymer chemistry, crosslinking approaches, and hydrogel fabrication methods, which have collectively brought many new hydrogel products, either injectable or non-injectable, to clinical studies. In an article published in 2020 entitled "Hydrogels in the clinic", we reviewed the clinical landscape and translational challenges of injectable hydrogels. Here, we provide an update on the advances in the field and also extend the scope to include non-injectable hydrogels. We highlight recently approved hydrogel products, provide an update on the clinical trials of injectable hydrogels, and discuss active clinical trials of topically applied and implantable hydrogels.

Advancements in hydrogel-based embolic agents: Categorized by therapeutic mechanisms

BACKGROUND

Transcatheter arterial embolization (TAE) is a crucial technique in interventional radiology. Hydrogel-based embolic agents show promise due to their phase transition and drug-loading capabilities. However, existing categorizations of these agents are confusing.

AIMS

This review tackles the challenge of categorizing hydrogel-based embolic agents based on their therapeutic mechanisms, including transportation, accumulation, interaction, and elimination. It also addresses current challenges and controversies in the field while highlighting future directions for hydrogel-based embolicagents.

MATERIALS AND METHODS

We conducted a systematic review of papers published in PUBMED from 2004 to 2024, focusing primarily on preclinical trials.

RESULTS

Various kinds of hydrogel embolic agents were introduced according to their therapeutic mechanisms.

DISCUSSION

Most hydrogel embolic agents were specifically designed for effective accumulation and interaction. Recent advancement highlight the potential of multifunctional hydrogel embolic agents.

CONCLUSION

This new categorizations provided valuable insights into hydrogel embolic agents, potentially guiding material scientists and interventional radiologists in the development of novel hydrogel embolic agents in transarterial embolization.

A First-in-Human Trial of a New Aqueous Ionic Liquid Embolic Material in Distal Embolization Applications

PURPOSE

A prospective, single-arm, open-label, multicenter, first-in-human, early feasibility study was completed to evaluate the safety and performance of the GPX Embolic Device (Fluidx, Salt Lake City, Utah), a novel liquid embolic agent, for use in the peripheral vasculature when deep distal embolization is desired.

MATERIALS AND METHODS

The early feasibility study evaluated the use of the device in the peripheral vasculature. Enrollment consisted of 17 patients with diverse embolization needs requiring deep distal vessel/vessel bed occlusion. Technical success, freedom from adverse events (AEs), and handling/performance characteristics were assessed with follow-up at 30 days.

RESULTS

The trial enrolled 17 patients requiring distal vascular penetration of the embolic agent, including 7 with renal angiomyolipomas, 4 with renal cell carcinomas (primary and secondary), 4 with portal veins needing embolization, 1 with pelvic sarcoma, and 1 with polycystic kidney. In all cases (100%), technical success was achieved with target regions fully occluded on the first angiogram (taken immediately after delivery). Furthermore, the material received high usability ratings, as measured by a postprocedural investigator questionnaire. Most patients (15/17, 88.2%) were free from device-related severe AEs, and there were no unanticipated AEs during the study. Each patient completed a 30-day follow-up evaluation, and sites remained fully occluded in each case where imaging was available (6 [35.3%] of 17 patients had follow-up imaging where all sites were deemed occluded [100%] with a mean of 30.2 days after the procedure).

CONCLUSIONS

The results of this first-in-human, early feasibility study demonstrate that the GPX Embolic Device may provide safe and effective embolization for arterial or venous applications where deep distal penetration is desired.

A novel gas embolotherapy using microbubbles electrocoalescence for cancer treatment

BACKGROUND AND OBJECTIVE

Embolotherapy has been increasingly used to disrupt tumor growth. Despite its success in the occlusion of microvessels, it has drawbacks such as limited access to the target location, limited control of the blocker size, and inattention to the tumor characteristics, especially high interstitial fluid pressure. The present work introduces a novel numerical method of gas embolotherapy for cancer treatment through tumor vessel occlusion.

METHODS

The gas microbubbles are generated from Levovist bolus injection into the tumor microvessel. The microbubble movement in the blood flow is innovatively controlled by an electric field applied to the tumor-feeding vessel. The interaction between the Levovist microbubbles and the electric field is resolved by developing a fully coupled model using the phase-field model, Carreau model for non-Newtonian blood, Navier-Stokes equations and Maxwell stress tensor. Additionally, the critical effect of high interstitial fluid pressure as a characteristic of solid tumors is included.

RESULTS

The findings of this study indicate that the rates of microbubble deformation and displacement increase with the applied potential intensity to the microvessel wall. Accordingly, the required time for a microbubble to join the upper microvessel wall reduces from 1.97ms to 22 μs with an increase of the electric potential from 3.5V to 12.5V. Additionally, an electric potential of 12.5V causes the microbubbles coalescence and formation of a gas column against the bloodstream.

CONCLUSIONS

Clinically, our novel embolization procedure can be considered a non-invasive targeted therapy, and under a controlled electric field, the blocker size can be precisely controlled. Also, the proposed method has the potential to be used as a gradual treatment in advanced cancers as tumors develop resistance and relapse.

Liquid Embolic Agents for Endovascular Embolization: A Review

Endovascular embolization (EE) has been used for the treatment of blood vessel abnormalities, including aneurysms, AVMs, tumors, etc. The aim of this process is to occlude the affected vessel using biocompatible embolic agents. Two types of embolic agents, solid and liquid, are used for endovascular embolization. Liquid embolic agents are usually injectable and delivered into the vascular malformation sites using a catheter guided by X-ray imaging (i.e., angiography). After injection, the liquid embolic agent transforms into a solid implant in situ based on a variety of mechanisms, including polymerization, precipitation, and cross-linking, through ionic or thermal process. Until now, several polymers have been designed successfully for the development of liquid embolic agents. Both natural and synthetic polymers have been used for this purpose. In this review, we discuss embolization procedures with liquid embolic agents in different clinical applications, as well as in pre-clinical research studies.

Nanoparticle-mediated therapeutic management in cholangiocarcinoma drug targeting: Current progress and future prospects

Patients with cholangiocarcinoma (CCA) often have an unfavorable prognosis because of its insidious nature, low resectability rate, and poor response to anticancer drugs and radiotherapy, which makes early detection and treatment difficult. At present, CCA has a five-year overall survival rate (OS) of only 5%, despite advances in therapies. New an increasing number of evidence suggests that nanoplatforms may play a crucial role in enhancing the pharmacological effects and in reducing both short- and long-term side effects of cancer treatment. This document reviews the advantages and shortcomings of nanoparticles such as liposomes, polymeric nanoparticle，inorganic nanoparticle, nano-metals and nano-alloys, carbon dots, nano-micelles, dendrimer, nano-capsule, bio-Nanomaterials in the diagnosis and treatment of CCA and discuss the current challenges in of nanoplatforms for CCA.