Temporary arterial embolization of liver parenchyma with degradable starch microspheres (EmboCept®S) in a swine model

Biodegradable Microspheres for Transarterial Chemoembolization in Malignant Liver Disease

Transarterial chemoembolization (TACE) has revolutionized the treatment landscape for malignant liver disease, offering localized therapy with reduced systemic toxicity. This manuscript delves into the use of degradable microspheres (DMS) in TACE, exploring its potential advantages and clinical applications. DMS-TACE emerges as a promising strategy, offering temporary vessel occlusion and optimized drug delivery. The manuscript reviews the existing literature on DMS-TACE, emphasizing its tolerability, toxicity, and efficacy. Notably, DMS-TACE demonstrates versatility in patient selection, being suitable for both intermediate and advanced stages. The unique properties of DMS provide advantages over traditional embolic agents. The manuscript discusses the DMS-TACE procedure, adverse events, and tumor response rates in HCC, ICC, and metastases.

The Use of Microspheres for Cancer Embolization Therapy: Recent Advancements and Prospective

Embolization therapy involving biomaterials has improved the therapeutic strategy for most liver cancer treatments. Developing biomaterials as embolic agents has significantly improved patients' survival rates. Various embolic agents are present in liquid agents, foam, particulates, and particles. Some of the most applied embolic agents are microparticles, such as microspheres (3D micrometer-sized spherical particles). Microspheres with added functionalities are currently being developed for effective therapeutic embolization. Their excellent properties of high surface area and capacity for being loaded with radionuclides and alternate active or therapeutic agents provide an additional advantage to overcome limitations from traditional cancer treatments. Microspheres (non-radioactive and radioactive) have been widely used and explored for localized cancer treatment. Non-radioactive microspheres exhibit improved clinical performance as drug delivery vehicles in chemotherapy due to their controlled and sustained drug release to the target site. They offer better flow properties and are beneficial for the ease of delivery via injection procedures. In addition, radioactive microspheres have also been exploited for use as an embolic platform in internal radiotherapy as an alternative to cancer treatment. This short review summarizes the progressive development of non-radioactive and radioactive embolic microspheres, emphasizing material characteristics. The use of embolic microspheres for various modalities of therapeutic arterial embolization and their impact on therapeutic performance are also discussed.

In vivo study of the utility of selective intra-arterial injection of thiopental for neuroprotection in reversible cerebral ischemia

BACKGROUND

Neuroprotective agents are needed to reduce cerebral damage during surgical or neurointerventional procedures including stroke patients.

PURPOSE

To evaluate if thiopental can be used as a neuroprotective agent when injected intra-arterially in a transient ischemia model.

MATERIAL AND METHODS

In total, 24 rabbits were studied as four groups of six animals. Group 1 served as the control group. In group 2, transient ischemia was obtained by intracarotid administration of degradable starch microspheres (DSM). Group 3 was administered thiopental intra-arterially via the carotid artery. Group 4 (experimental group) received both thiopental and DSM intra-arterially. DSM and thiopental were administered through a microcatheter placed into the common carotid artery via the central ear artery access. After sacrifice, apoptotic cells in the cerebral tissues of the animals were evaluated in H&E and TUNEL stained slides.

RESULTS

There was a significant increase in the number of apoptotic glial or neuronal cells in group 2 compared to the control group and group 3. The mean number of both the apoptotic neuronal cells (6.8 ± 2.1 vs. 2.5 ± 1.3, P < 0.001) and the apoptotic glial cells (9.4 ± 3.1 vs. 4.6 ± 1.6, P < 0.001) were higher in group 2 compared to group 4. In addition, a higher level of neurological improvement was observed in group 4 compared to group 2 based on neurological assessment score.

CONCLUSION

The intra-arterial administration of thiopental has a protective effect on both glial and neuronal cells during temporary cerebral ischemia in low doses.

Hepatic arterial infusion with nanoliposomal irinotecan leads to significant regression of tumor size of colorectal liver metastases in a CC531 rat model

Long-term therapy for unresectable colorectal liver metastases remains challenging. Intraarterial treatments aim to avoid systemic adverse effects of chemotherapy. Nanoliposomal cytotoxic drugs manage to increase the drug concentration within the tumor while reducing toxicity in healthy tissue.  In this study we analyzed the effect of hepatic arterial infusion (HAI) with nanoliposomal irinotecan with or without the combination of embolization particles in a rat model for colorectal liver metastases. For the study 32 WAG/Rij rats received subcapsular tumor implantation with CC531 rat colonic adenocarcinoma cells. After ten days tumor size was assessed via ultrasound and animals underwent HAI. One group served as control receiving NaCl 0.9 % (Sham), the three treatment groups received either nanoliposomal irinotecan (HAI nal iri), Embocept® S (HAI Embo) or Embocept® S and nanoliposomal irinotecan (HAI Embo+nal iri). Three days after treatment animals were sacrificed after assessment of tumor size. As a result all treatment groups showed a significant reduction in tumor growth compared to Sham (p<0.05). Expression of the apoptosis marker caspase-3 was enhanced in HAI nal iri and HAI Embo+nal iri compared to Sham and HAI Embo and  even significantly enhanced after HAI Embo+nal iri in comparison to Sham (p<0.05). We were able to show that HAI with Embocept® S led to significantly reduced tumor growth while HAI with nanoliposomal irinotecan alone or in combination with Embocept® S even led to a reduction of tumor size. Thus, we demonstrate that intraarterial treatment with nanoliposomal irinotecan effectively inhibits tumor growth in a rat model of colorectal liver metastases and demands further investigation.

Clinical Outcomes of Radiofrequency Ablation Combined with Transarterial Chemoembolization Using Degradable Starch Microsphere Mixed with Mitomycin C for the Treatment of Non-hepatocellular Carcinoma Malignant Liver Tumors

Purpose

To retrospectively evaluate the outcomes of radiofrequency ablation combined with transarterial chemoembolization using degradable starch microspheres for non-hepatocellular carcinoma malignant liver tumors.

Material and Methods

A total of 15 patients (13 men, 2 women; median age, 67 years) who underwent radiofrequency ablation immediately after transarterial chemoembolization using degradable starch microspheres for liver tumors between July 2011 and September 2020 were included in this study. Thirteen patients had liver metastases from colorectal cancer (n = 6), esophageal cancer (n = 2), lung cancer (n = 2), and other tumors (n = 3), and 2 patients had primary liver tumor of cholangiocellular carcinoma (n = 1) and gastrinoma (n = 1). Twenty tumors (median size, 16 mm) were treated in 17 sessions. Technical success, safety, local tumor progression, and overall survival were evaluated. Safety was assessed according to the clinical practice guideline of the Society of Interventional Radiology.

Results

All treatment procedures were successfully completed. There were no major complications. Grade-B complications of self-limiting pneumothorax (n = 1), vomiting (n = 1), and fever (n = 1) occurred in 1 session each. Local tumor progression developed in two tumors (local tumor progression rate, 10%, 2/20). The local tumor progression rates were 5% and 11% at 1 year and at 3 and 5 years, respectively. Tumor size of more than 20 mm (P = 0.0003) and contact with major vessels (P = 0.03) were significant risk factors for local tumor progression. The patients were treated with repeat radiofrequency ablation combined with transarterial chemoembolization using degradable starch microspheres. During median follow-up of 48 months (range, 4-77 months), 5 patients died (33%, 5/15). The overall survival rates were 100%, 85%, and 57% at 1, 3, and 5 years, respectively. The median overall survival time was 69 months.

Conclusions

Radiofrequency ablation combined with transarterial chemoembolization using degradable starch microspheres was safe and showed favorable local control for non-hepatocellular carcinoma malignant liver tumors.

Smart nanoparticles and microbeads for interventional embolization therapy of liver cancer: state of the art

The process of transcatheter arterial chemoembolization is characterized by the ability to accurately deliver chemotherapy drugs with minimal systemic side effects and has become the standard treatment for unresectable intermediate hepatocellular carcinoma (HCC). However, this treatment option still has much room for improvement, one of which may be the introduction of nanomaterials, which exhibit unique functions and can be applied to in vivo tumor imaging and therapy. Several biodegradable and multifunctional nanomaterials and nanobeads have recently been developed and applied in the locoregional treatment of hepatocellular cancer. This review explores recent developments and findings in relation to micro-nano medicines in transarterial therapy for HCC, emerging strategies to improve the efficacy of delivering nano-based medicines, and expounding prospects for clinical applications of nanomaterials.

Silk-elastinlike protein-based hydrogels for drug delivery and embolization

Silk-Elastinlike Protein-Based Polymers (SELPs) can form thermoresponsive hydrogels that allow for the generation of in-situ drug delivery matrices. They are produced by recombinant techniques, enabling exact control of monomer sequence and polymer length. In aqueous solutions SELP strands form physical crosslinks as a function of temperature increase without the addition of crosslinking agents. Gelation kinetics, modulus of elasticity, pore size, drug release, biorecognition, and biodegradation of SELP hydrogels can be controlled by placement of amino acid residues at strategic locations in the polymer backbone. SELP hydrogels have been investigated for delivery of a variety of bioactive agents including small molecular weight drugs and fluorescent probes, oligomers of glycosaminoglycans, polymeric macromolecules, proteins, plasmid DNA, and viral gene delivery systems. In this review we provide a background for use of SELPs in matrix-mediated delivery and summarize recent investigations of SELP hydrogels for controlled delivery of bioactive agents as well as their use as liquid embolics.

Emerging Polymer Materials in Trackable Endovascular Embolization and Cell Delivery: From Hype to Hope

Minimally invasive endovascular embolization is a widely used clinical technique used for the occlusion of blood vessels to treat various diseases. Different occlusive agents ranging from gelatin foam to synthetic polymers such as poly(vinyl alcohol) (PVA) have been commercially used for embolization. However, these agents have some drawbacks, such as undesired toxicity and unintended and uncontrolled occlusion. To overcome these issues, several polymer-based embolic systems are under investigation including biocompatible and biodegradable microspheres, gelling liquid embolic with controlled occlusive features, and trackable microspheres with enhanced safety profiles. This review aims to summarize recent advances in current and emerging polymeric materials as embolization agents with varying material architectures. Furthermore, this review also explores the potential of combining injectable embolic agents and cell therapy to achieve more effective embolization with the promise of outstanding results in treating various devastating diseases. Finally, limitations and challenges in developing next-generation multifunctional embolic agents are discussed to promote advancement in this emerging field.

Shape-Anisotropic Microembolics Generated by Microfluidic Synthesis for Transarterial Embolization Treatment

Particulate embolic agents with calibrated sizes, which employ interventional procedures to achieve endovascular embolization, have recently attracted tremendous interest in therapeutic embolotherapies for a wide plethora of diseases. However, the particulate shape effect, which may play a critical role in embolization performances, has been rarely investigated. Here, polyvinyl alcohol (PVA)-based shape-anisotropic microembolics are developed using a facile droplet-based microfluidic fabrication method via heat-accelerated PVA-glutaraldehyde crosslinking reaction at a mild temperature of 38 ^° C. Precise geometrical controls of the microembolics are achieved with a nearly capsule shape through regulating surfactant concentration and flow rate ratio between dispersed phase and continuous phase in the microfluidics. Two specific models are employed, i.e., in vitro decellularized rabbit liver embolization model and in vivo rabbit ear embolization model, to systematically evaluate the embolization behaviors of the nonspherical microembolics. Compared to microspheres of the same volume, the elongated microembolics demonstrated advantageous endovascular navigation capability, penetration depth and embolization stability due to their comparatively smaller radial diameter and their central cylindrical part providing larger contact area with distal vessels. Such nonspherical microembolics present a promising platform to apply shape anisotropy to achieve distinctive therapeutic effects for endovascular treatments.

Trans-Arterial Chemoembolization with 50 μm Degradable Starch Microspheres Versus 300–500 μm Drug Eluting Beads in Hepatocellular Carcinoma: A Comparative Analysis of Initial Treatment Outcomes

Background and Aims:

Trans-arterial chemoembolization (TACE) has become a widely accepted treatment in unresectable hepatocellular carcinoma (HCC). We aimed at comparing the efficacy of Degradable Starch Microspheres (DSMs)-TACE with 50 ± 7 µm versus 300–500 μm Drug Eluting Beads (DEB)-TACE in terms of initial clinical and radiological treatment response parameters.

Material and Methods:

A total of 54 patients with unresectable HCC who underwent DEB-TACE (n = 25) or DSMs-TACE (n = 29) were included in this retrospective study. Baseline demographic and clinical characteristics, duration of follow-up, local recurrence and survival status, as well as treatment outcome including treatment response via modified Response Evaluation Criteria in Solid Tumors (mRECIST) criteria, viable and total tumor diameter and serum alpha-fetoprotein (AFP) levels were analyzed in both study groups.

Results:

No significant difference was noted between the two groups in terms of local recurrence (31.6 vs. 16.7%) or mortality (73.9 vs. 85.7%) rates after 36-month and 12-month follow-up, respectively. DSMs-TACE vs. DEB-TACE was associated with significantly higher complete response rate (27.6 vs. 0.0%, p = 0.011) and significant decrease in serum AFP levels (p = 0.013).

Conclusion:

Both DSMs-TACE with 50 ± 7 µm microspheres and 300–500 μm DEB-TACE are effective for local control of unresectable HCC. Our findings revealed superiority of DSMs-TACE over DEB-TACEnin terms of initial clinical and radiological tumor response; though no significant difference was noted between the two patient groups in terms of local recurrence or mortality during follow up.

Recent advances and applications of microspheres and nanoparticles in transarterial chemoembolization for hepatocellular carcinoma

Transarterial chemoembolization (TACE) is a recommended treatment for patients suffering from intermediate and advanced hepatocellular carcinoma (HCC). As compared to the conventional TACE, drug-eluting bead TACE demonstrates several advantages in terms of survival, treatment response, and adverse effects. The selection of embolic agents is critical to the success of TACE. Many studies have been performed on the modification of the structure, size, homogeneity, biocompatibility, and biodegradability of embolic agents. Continuing efforts are focused on efficient loading of versatile chemotherapeutics, controlled sizes for sufficient occlusion, real-time detection intra- and post-procedure, and multimodality imaging-guided precise treatment. Here, we summarize recent advances and applications of microspheres and nanoparticles in TACE for HCC. This article is categorized under: Therapeutic Approaches and Drug Discovery > Nanomedicine for Oncologic Disease.

SmartPAN: in vitro and in vivo proof-of-safety assessments for an intra-operative predictive indicator of postoperative pancreatic fistula

Pancreatic surgery is complicated by untreated fluid leakage, but no tenable techniques exist to detect and close leakage sites during surgery. A novel hydrogel called SmartPAN has been developed to meet this need and is here assessed for safety before trials on human patients. Firstly, resazurin assays were used to test the cytotoxic effects of SmartPAN's active bromothymol blue (BTB) indicator and its solution of phosphate-buffered saline (PBS) on normal (HPDE: Human Pancreatic Duct Epithelial) or carcinomic (FAMPAC) human pancreatic cells. Cells incubated with BTB showed no significant reduction in cell viability below threshold safety levels. However, PBS had a mild cytotoxic effect on FAMPAC cells. Secondly, SmartPAN's pathological effects were evaluated in vivo by applying 4 mL SmartPAN to a porcine (Sus scrofa domesticus) model of pancreatic resection. There were no significant differences in macroscopic and microscopic pathologies between pigs treated with SmartPAN or saline. Thirdly, measurements using HPLC-MS/MS demonstrate that BTB does not cross into the bloodstream and was eliminated from the body within two days of surgery. Overall, SmartPAN appears safe in the short-term and ready for first-in-human trials because its components are either biocompatible or quickly neutralized by dilution and drainage.

European Multicenter Study on Degradable Starch Microsphere TACE: The Digestible Way to Conquer HCC in Patients with High Tumor Burden

To evaluate the safety and efficacy of transarterial chemoembolization with degradable starch microspheres (DSM-TACE) for the treatment of hepatocellular carcinoma (HCC) with a high tumor burden ineligible for or failing other palliative therapies, 121 patients from three European centers were included. Kaplan-Meier analysis was used for median overall survival (OS) and time to progression (TTP, mRECIST criteria) in months with a 95% confidence interval (95% CI). Uni- (UVA) and multivariate (MVA) analyses were performed using the Cox Proportional Hazard Model. The median OS of the study cohort was 15.5 (13.3-18.7) months. The UVA identified HCC lesions ≤10 cm, unilobar involvement, lower Child-Pugh class and Barcelona Clinic Liver Cancer (BCLC) stage, absence of vascular invasion, and extrahepatic metastases as factors for prolonged survival. MVA confirmed lesions of ≤10 cm and unilobar disease as independent OS factors. Median TTP was 9.5 (7.6-10.3) months. The best response was achieved after a median of 3 (range: 1-6) treatments with CR/PR/SD/PD in 13.5%/44.5%/25.2%/16.8%, respectively. DSM-TACE was well tolerated with no major clinical adverse events and only limited major laboratory events. Preserved liver function was observed after repetitive DSM-TACE treatments. Repetitive DSM-TACE is a safe, well-tolerated and effective treatment option for HCC patients with high tumor burden ineligible or failing other palliative therapies.

Safety and effectiveness of new embolization microspheres SCBRM for intermediate-stage hepatocellular carcinoma: A feasibility study

Transarterial chemoembolization (TACE) is, currently, the recommended treatment for hepatocellular carcinoma (HCC). However, long-term chemoembolization triggers the inflammatory response and may lead to postembolization syndrome (PES). Although several types of degradable microspheres have been developed to reduce drug toxicity and PES incidence, the clinical outcomes remain unsatisfactory. Previously, we have developed a new type of spherical, calibrated, biodegradable, radiopaque microspheres (SCBRM) and demonstrated their safety and efficacy in a pig model. Thus, the goal of this feasibility study was to determine the clinical safety and efficacy of the new SCBRM in intermediate-stage HCC patients. In this study, 12 intermediate-stage HCC patients underwent TACE using SCBRM with a calibrated size of 100–250 μm. The disease control rates at 1 month and 3 months after TACE-SCBRM treatment were 100% and 75.0%, respectively. The objective response rates at 1 month and 3 months after treatment were 66.7% and 58.3%, respectively. Very few adverse events were observed with one patient developing nausea. One day after the treatment, alanine aminotransferase, alanine aminotransferase, and total bilirubin levels were slightly elevated in the patients, but all returned to baseline on day 7. The median and mean overall survival times were 33 months (interquartile range, 12.8–42.0) and 29.2 ± 14.3 months, respectively. The 1-year and 2-year survival rates were 91.7% and 58.3%, respectively. In conclusion, TACE with the new SCBRM microspheres is clinically safe and effective, and it represents a promising approach in the management of intermediate-stage HCC.

Safety and Efficacy of Degradable Starch Microspheres Transcatheter Arterial Chemoembolization as a Bridging Therapy in Patients with Early Stage Hepatocellular Carcinoma and Child-Pugh Stage B Eligible for Liver Transplant

In patients with early-stage hepatocellular carcinoma, awaiting liver transplantation, current guidelines by AASLD and ESMO recommend a bridging therapy with a loco-regional treatment to prevent progression outside transplantation criteria. The standard of care in delaying disease progression has been recognized to be the transarterial chemoembolization. Permanent occlusion of tumor feeding vessels has effects on tumour stromal microenvironment by inducing intra- and intercellular signaling processes counteracting hypoxia, such as the release of vascular endothelial growth factor, a promoter of neoangiogenesis, tumour proliferation and metastatic growth. Among chemoembolization interventions, TACE with degradable starch microspheres represents an alternative to conventional cTACE and DEB-TACE and it minimizes detrimental effects on tumour stromal microenvironment, guaranteeing a transient occlusion of tumour feeding arteries and avoiding VEGF overexpression.Between January 2015 and September 2020, 54 consecutive patients with early-stage hepatocellular carcinoma and Child-Pugh stage B, who had undergone DSM-TACE as a bridging therapy while awaiting liver transplantation, were eligible for the study. A total of 154 DSM-TACE was performed, with a mean number of 2.85 procedures per patient. 18 patients (33.3%) succeeded in achieving liver transplantation, with a mean waiting time-to-transplantation of 11.7 months. The cumulative rates of patients still active on the WL at 6 months were about 91 and 93% when considering overall drop-out and tumour-specific drop-out respectively. Overall survival was about 96% at 6 months and 92% at 12 months. 17 patients experienced adverse events after the chemoembolizations. For patients with HCC in the transplant waiting list and within the Child-Pugh B stage, life expectancy may be dominated by the liver dysfunction, rather than by the tumour progression itself. In this population subset, the choice of LRT is critical because LRT itself could become a dangerous tool that is likely to precipitate liver dysfunction to an extent that survival is shortened rather than prolonged. Hence, the current study demonstrates that DSM-TACE is not far from being an ideal LRT, because it has an excellent safety profile, maintaining an efficacy that guarantees a clear advantage on the dropout rate with respect to the non-operative strategy, thus justifying its use.

Biodegradable Polydioxanone Microspheres for Transcatheter Arterial Embolization: Proof of Principle

PURPOSE

To evaluate feasibility, embolization success, biodegradability, reperfusion, and biocompatibility of biodegradable microspheres (MS) made from polydioxanone (PDO) for transcatheter arterial embolization.

MATERIALS AND METHODS

Unilateral selective renal embolization of a segmental artery was performed in 16 New Zealand White rabbits with PDO-MS (100-150 μm and 90-315 μm). Animals were randomly assigned to different observation periods and underwent control digital subtraction angiography (DSA) and MR imaging immediately (n = 3), 1 week (n = 2), 4 weeks (n = 2), 8 weeks (n = 2), 12 weeks (n = 5), and 16 weeks (n = 2) after embolization. Kidneys were harvested for macroscopic and histologic analysis of embolization success, biodegradability, and biocompatibility.

RESULTS

Embolization was technically successful in 15 of 16 animals. One animal died of anesthesia-related circulatory failure. The 100-150 μm MS were injected easily through 3-F catheters; the 90-315 μm MS tended to clog with intermittent catheter obstruction. DSA and MR imaging showed successful target embolization in 13 of 15 animals. In 2 animals, the entire kidney was affected owing to catheter clogging, including a reflux of MS while flushing. Control DSA and MR imaging showed increasing vascular reperfusion with time. Macroscopic and histologic analysis revealed necrosis/infarction in areas in which embolization was achieved. MS were extensively degraded after 16 weeks, and overall inflammatory reaction was mild.

CONCLUSIONS

Biodegradable PDO-MS induced effective embolization of target vessels while demonstrating good biocompatibility. MS increasingly dissolved at 16 weeks, partial reperfusion started at week 1, and complete reperfusion started at week 8, thus offering possible advantages as a temporary embolic agent.

Novel MR-Visible, Biodegradable Microspheres for Transcatheter Arterial Embolization: Experimental Study in a Rabbit Renal Model

PURPOSE

To assess feasibility, embolization success, biodegradability, reperfusion, biocompatibility and in vivo visibility of novel temporary microspheres (MS) for transcatheter arterial embolization.

MATERIAL AND METHODS

In 9 New Zealand white rabbits unilateral superselective embolization of the lower kidney pole was performed with biodegradable MS made of polydioxanone (PDO) (size range 90-300 and 200-500 µm) impregnated with super-paramagnetic iron oxide (SPIO). Magnetic resonance imaging (MRI) was performed post-interventionally to assess in vivo visibility. Embolization success was assessed on digital subtraction angiography, MRI and gross pathology. One animal was killed immediately after embolization to assess original particle appearance. 8 animals were randomly assigned to different observation periods (1, 4, 8, 12 and 16 weeks), after which control angiography and MRI were obtained to determine recanalization. Histopathological analysis was performed to determine biodegradability and biocompatibility by using dedicated quantitative assessment analysis.

RESULTS

Ease of injection was moderate. Embolization was technically successful in 7 of 8 animals, one rabbit received non-selective embolization of the whole kidney and abdominal off-target embolization. Arterial occlusion was achieved in all kidneys, infarct areas in macro- and microscopic analysis confirmed embolization success. Control angiograms showed evidence of partial reperfusion. The microspheres showed extensive degradation over the course of time along with increasing inflammatory response and giant cell formation. SPIO-loaded MS were visible on MRI at all time points.

CONCLUSIONS

SPIO-impregnated biodegradable PDO-MS achieved effective embolization with in vivo visibility on MRI and increasing biodegradation over time while demonstrating good biocompatibility, i.e., a physiologically immune response without transformation into chronic inflammation. Further studies are needed to provide clinical applicability.

Degradable starch microspheres transarterial chemoembolization (DSMs-TACE) in patients with unresectable hepatocellular carcinoma (HCC): long-term results from a single-center 137-patient cohort prospective study

PURPOSE

To evaluate safety and efficacy of degradable starch microspheres (DSMs) TACE in a large clinical cohort of patients with unresectable HCC.

MATERIALS AND METHODS

This is a single-center consecutive patients cohort study. The study was approved by local institutional ethics committee. Written informed consent was obtained. From December 2013 to March 2018, 137 cirrhotic patients with unresectable HCC were enrolled. For DSMs-TACE, a mixture of 4 mL of DSMs, 6 mL of non-ionic contrast and doxorubicin at a dose of 50 mg/m² were used. Primary end point was long-term outcome, in terms of time to progression (TTP) and overall survival (OS). Secondary endpoints were: safety, liver toxicity, 1-month percentage of tumor necrosis according to the modified RECIST criteria.

RESULTS

Two hundred and sixty-seven DSMs-TACE were performed in 137 HCC patients (33 patients in BCLC stage A, 84 patients in BCLC stage B, and 20 in stage C). Patients had a mean nodule number of 3.5 ± 1.2 (SD). Major complications were observed in 6.8% of cases. Post-embolization syndrome was common (101 patients 73.7%). According to mRecist criteria, a high objective response rate was obtained even after just one treatment (84.3% of patients showed complete response or partial response). The median TTP and OS after DSMs-TACE were 12 months and 36 months, respectively. OS at 6 months, 1 year, 2 and 3 years was 98%, 81.3%, 57.9%, 34.9%, respectively.

CONCLUSION

DSMs-TACE is a safe and effective therapy for patients with HCC, allowing to obtain a good rate of OS with excellent local tumor control.

Characterization of Calibrated Gelatin Sponge Particles in a Rabbit Renal Embolization Model

PURPOSE

To evaluate the level of artery occlusion, degradation periods, tissue response and vessel recanalization of calibrated gelatin sponge particles after segmental renal artery embolization.

MATERIALS AND METHODS

Superselective embolization of 14 adult rabbits was performed with calibrated gelatin sponge particles (150-350 μm). Two rabbits were killed immediately after the procedure (day 0). One pair of rabbits was killed on each of the following days: 1, 3, 7, 14, 28 and 56. One rabbit from each pair underwent CT angiography before embolization and killing. The pathologic changes of the embolized renal parenchyma and embolic characteristics of calibrated gelatin sponge particles were evaluated histologically and angiographically.

RESULTS

Calibrated gelatin sponge particles were distally located in interlobular artery with a dense packing on day 0. The level of occlusion paralleled the size of the particles. Partial degradation of the particles was observed on day 3, and complete degradation was observed on day 14. Vessel recanalization was observed through both CTA and histological analysis starting on day 3. Vascular inflammation responding to gelatin sponge particles was mild and subsided with the degradation of the particles. On day 28 and day 56, attenuation of embolized vessels occurred due to marked intimal proliferation, and vascular occlusion developed.

CONCLUSIONS

Gelatin sponge particles of 150-350 μm produced dense and distal embolization, and were resorbed before day 14 with a mild tissue reaction. Vessel recanalization occurred secondary to the resorption of gelatin sponge particles, but permanent vascular occlusion developed due to marked intimal hyperplasia after day 28.

Hepatic arterial infusion of irinotecan and EmboCept® S results in high tumor concentration of SN-38 in a rat model of colorectal liver metastases

Intraarterial chemotherapy for colorectal liver metastases (CRLM) can be applied alone or together with embolization particles. It remains unclear whether different types of embolization particles lead to higher intratumoral drug concentration. Herein, we quantified the concentrations of CPT-11 and its active metabolite SN-38 in plasma, liver and tumor tissue after hepatic arterial infusion (HAI) of irinotecan, with or without further application of embolization particles, in a rat model of CRLM. Animals underwent either systemic application of irinotecan, or HAI with or without the embolization particles Embocept^® S and Tandem™. Four hours after treatment concentrations of CPT-11 and SN-38 were analyzed in plasma, tumor and liver samples by high-performance liquid chromatography. Additionally, DNA-damage and apoptosis were analyzed immunohistochemically. Tumor tissue concentrations of SN-38 were significantly increased after HAI with irinotecan and EmboCept^® S compared to the other groups. The number of apoptotic cells was significantly higher after both HAI with irinotecan and EmboCept^® S or Tandem™ loaded with irinotecan compared to the control group. HAI with irinotecan and EmboCept^® S resulted in an increased SN-38 tumor concentration. Both HAI with irinotecan and EmboCept^® S or Tandem™ loaded with irinotecan were highly effective with regard to apoptosis.

Repeated Transarterial Chemoembolization with Degradable Starch Microspheres (DSMs-TACE) of Unresectable Hepatocellular Carcinoma: A Prospective Pilot Study

OBJECTIVE

The aims of this study were to: a) evaluate tumor response rates using modified-Response-evaluation-criteria-in-solid-tumors (mRecist) criteria, b) evaluate safety of Degradable Starch Microspheres Trans-arterial-chemo-embolization (DSMs-TACE) for unresectable hepatocellular-carcinoma (HCC) treatment.

MATERIALS AND METHODS

We prospectively enrolled 24 HCC cirrhotic patients (21/3 M/F, mean age 66.3 years) to be treated with repeated DSMs-TACE procedures, performed at 4-6 week intervals on the basis of tumor response and patients tolerance. Clinical and biochemical evaluations were performed before and after each procedure. Treatment response was also assessed by Computed-tomography (CT) or Magnetic-resonance-imaging (MRI)-scan 4-6 weeks following each procedure.

RESULTS

In our experience, DSMs-TACE was both safe and effective. A total of 53 DSMs-TACE procedures were performed (2.2 per patient). No procedure-related death was observed. Complete Response (CR) was observed in 5/24 (20.8%), 4/17 (23.5%) and 5/12 (41.6%) patients after the first, second and third procedure, respectively. At the end of each treatment, all patients experienced at least a partial response. At the end of the repeated procedures, no differences between mono- or bi-lobar disease were observed in patients with CR (64.2% vs 50%; p=ns). In most cases, treatment discontinuation was due to worsening liver function.

CONCLUSION

DSMs-TACE is a valid, well-tolerated alternative treatment to Lipiodol-TACE or DEB-TACE, as it has demonstrated to achieve a relatively high percentage of complete tumor necrosis. CR rates were similar between patients with mono- or bi-lobar disease indicating the possibility of carrying-out repeated procedure in a safe and effective way in both types of patients.

Long-Term Implantability of Resorbable Carboxymethyl Cellulose/Chitosan Microspheres in a Rabbit Renal Arterial Embolization Model

PURPOSE

To determine the physiologic response to resorbable carboxymethyl cellulose/chitosan (CMC/CN) microspheres in a long-term rabbit model, including the clinical response, gross pathology, and histopathology.

MATERIALS AND METHODS

Six rabbits were embolized with CMC/CN microspheres (300-500 µm) in one kidney via an inferior renal artery branch. Angiography was performed immediately before and after embolization and prior to killing at 6 months (180 ± 7 days, n = 3) and 12 months (365 ± 10 days, n = 3). A complete necropsy was performed on each animal with dissection of the kidneys and harvesting of additional tissues as per ISO-10993-part 6 and ISO-10993-part 11 guidelines. All tissues were processed and stained for pathological analysis.

RESULTS

The caudal third of target kidneys was successfully embolized with CMC/CN microspheres. Over the course of the study, there were neither notable clinical signs in either embolization group nor significant changes in the tissue/body weight ratio between 6- and 12-month time points. Gross examination revealed that all embolized kidneys had morphologic features consistent with infarction resulted from microsphere delivery. The percentage of infarction decreased from 9.1% ± 5.7% at 6 months to 1.9% ± 0.4% at 12 months. Microscopically, infarcted areas demonstrated evidence of chronic injury and repair, including loss of renal parenchyma with replacement fibrosis, tubular regeneration, and minimal to mild lymphoplasmacytic inflammation without any active changes such as necrosis or neutrophilic inflammation.

CONCLUSION

No systemic toxicity was observed in the animals 6 and 12 months after CMC/CN microspheres delivery. The local tissue response was mild.

Drug-eluting embolic microspheres for local drug delivery - State of the art

Embolic microspheres or beads used in transarterial chemoembolization are an established treatment method for hepatocellular carcinoma patients. The occlusion of the tumor-feeding vessels by intra-arterial injection of the beads results in tumor necrosis and shrinkage. In this short review, we describe the utility of using these beads as devices for local drug delivery. We review the latest advances in the development of non-biodegradable and biodegradable drug-eluting beads for transarterial chemoembolization. Their capability to load different drugs, such as chemotherapeutics and anti-angiogenic compounds with different physicochemical properties, like charge and hydrophilicity/hydrophobicity, are discussed. We specifically address controlled and sustained drug release from the microspheres, and the resulting in vivo pharmacokinetics in the plasma vs. drug distribution in the targeted tissue.

Polymeric materials for embolic and chemoembolic applications

Percutaneous transcatheter embolization procedures involve the selective occlusion of blood vessels. Occlusive agents, referred to as embolics, vary in material characteristics including chemical composition, mechanical properties, and the ability to concurrently deliver drugs. Commercially available polymeric embolics range from gelatin foam to synthetic polymers such as poly(vinyl alcohol). Current systems under investigation include tunable, bioresorbable microspheres composed of chitosan or poly(ethylene glycol) derivatives, in situ gelling liquid embolics with improved safety profiles, and radiopaque embolics that are trackable in vivo. This article reviews commercially available materials used for embolization as well as polymeric materials that are under investigation.

Intermediate hepatocellular carcinoma: the role of transarterial therapy

According to Barcelona Clinic Liver Cancer, the recommended first-line treatment for patients with intermediate stage of hepatocellular carcinoma (HCC) is transarterial chemoembolization. Patients with intermediate stage of HCC represent 20% with a 2-year survival of approximately 50%. Nowadays, transarterial therapies have proved precious in the treatment of hepatic malignancies. During the last years, there were important developments in practiced transarterial therapies and their efficacy is still controversial. The purpose of this review is to discuss in further details these transarterial therapies that have been used to treat cases of HCC.