Therapeutic use of 90Y microspheres

[90Y]Yttria Alumino Silicate Glass Microspheres: A Biosimilar Formulation to "TheraSphere" for Cost-Effective Treatment of Liver Cancer

Background: Selective internal radiation therapy (SIRT) using a suitable β--emitting radionuclide is a promising treatment modality for unresectable liver carcinoma. Yttrium-90 (90Y) [T1/2 = 64.2 h, Eβ(max) = 2.28 MeV, no detectable γ-photon] is the most preferred radioisotope for SIRT owing to its favorable decay characteristics. Objective: The present study describes indigenous development and evaluation of intrinsically radiolabeled [90Y]yttria alumino silicate ([90Y]YAS) glass microsphere, a formulation biosimilar to "TheraSphere" (commercially available, U.S. FDA-approved formulation), for SIRT of unresectable liver carcinoma in human patients. Methods: YAS glass microspheres of composition 40Y2O3-20Al2O3-40SiO2 (w/w) and diameter ranging between 20 and 36 μm were synthesized with almost 100% conversion efficiency and >99% sphericity. Intrinsically labeled [90Y]YAS glass microspheres were produced by thermal neutron irradiation of cold YAS glass microspheres in a research reactor. Subsequent to in vitro evaluations and in vivo studies in healthy Wistar rats, customized doses of [90Y]YAS glass microspheres were administered in human patients. Results: [90Y]YAS glass microspheres were produced with 137.7 ± 8.6 MBq/mg YAS glass (∼6800 Bq per microsphere) specific activity and 99.94% ± 0.02% radionuclidic purity at the end of irradiation. The formulation exhibited excellent in vitro stability in human serum and showed >97% retention in the liver up to 7 d post-administration when biodistribution studies were carried out in healthy Wistar rats. Yttrium-90 positron emission tomography scans recorded at different time points post-administration of customized dose of [90Y]YAS glass microspheres in human patients showed near-quantitative retention of the formulation in the injected lobe. Conclusions: The study confirmed the suitability of indigenously prepared [90Y]YAS glass microspheres for clinical use in the treatment of unresectable hepatocellular carcinoma.

Size effect of fluorescent thiol-organosilica particles on their distribution in the mouse spleen

We investigated the distribution of intravenously administered thiol-organosilica particle (thiol-OS) in the spleen to evaluate their size effect in mice. A single administration of particles of thiol-OS containing rhodamine B (Rh) (90, 280, 340, 450, 630, 1110, 1670, and 3030 nm in diameter) was performed. After 24 h, we conducted a combination analysis using histological studies by fluorescent microscopy and quantitative inductively coupled plasma optical emission spectrometry (ICP-OES), which revealed no clear correlation between the particle size and spleen uptake of particle weight and number per tissue weight, and the injection dose. Moreover, Rh with 450 nm diameter (Rh450) showed the highest uptake, and Rh with 340 nm diameter (Rh340) showed the lowest uptake. Histologically, large fluorescent areas in the marginal zone (MZ) and red pulp (RP) of the spleen were observed for all particle sizes, but less in the follicle of white pulp. Using combination analysis using the particle weights of ICP-OES and the fluorescent area, we compared the distributions of each particle in each region. Rh450 had the largest accumulated weight in the MZ and RP. Particles larger than Rh450 showed negative correlations between their sizes and accumulated weight in the MZ and RP. Simultaneous dual administration of particles using Rhs and thiol-OS containing fluorescein (90 nm in diameter) showed the size-dependent difference in cellular distribution and intracellular localization. Immunohistochemical staining against macrophage markers, CD169, and F4/80 showed various colocalization patterns with macrophages that uptook particles, indicating differences in particle uptake in each macrophage may have novel significance.

Activation of nano-photosensitizers by Y-90 microspheres to enhance oxidative stress and cell death in hepatocellular carcinoma

While radioembolization with yttrium-90 (Y-90) microspheres is a promising treatment for hepatocellular carcinoma (HCC), lower responses in advanced and high-grade tumors present an urgent need to augment its tumoricidal efficacy. The purpose of this study was to determine whether clinically used Y-90 microspheres activate light-responsive nano-photosensitizers to enhance hepatocellular carcinoma (HCC) cell oxidative stress and cytotoxicity over Y-90 alone in vitro. Singlet oxygen and hydroxyl radical production was enhanced when Y-90 microspheres were in the presence of several nano-photosensitizers compared to either alone in cell-free conditions. Both the SNU-387 and HepG2 human HCC cells demonstrated significantly lower viability when treated with low activity Y-90 microspheres (0.1-0.2 MBq/0.2 mL) and a nano-photosensitizer consisting of both titanium dioxide (TiO2) and titanocene (TC) labelled with transferrin (TiO2-Tf-TC) compared to Y-90 microspheres alone or untreated cells. Cellular oxidative stress and cell death demonstrated a linear dependence on Y-90 at higher activities (up to 0.75 MBq/0.2 mL), but was significantly more accentuated in the presence of increasing TiO2-Tf-TC concentrations in the poorly differentiated SNU-387 HCC cell line (p < 0.0001 and p = 0.0002 respectively) but not the well-differentiated HepG2 cell line. Addition of TiO2-Tf-TC to normal human hepatocyte THLE-2 cells did not increase cellular oxidative stress or cell death in the presence of Y-90. The enhanced tumoricidal activity of nano-photosensitizers with Y-90 microspheres is a potentially promising adjunctive treatment strategy for certain patient subsets. Applications in clinically relevant in vivo HCC models are underway.

Cerium Containing Bioactive Glasses: A Review

Bioactive glasses (BGs) for biomedical applications are doped with therapeutic inorganic ions (TIIs) in order to improve their performance and reduce the side effects related to the surgical implant. Recent literature in the field shows a rekindled interest toward rare earth elements, in particular cerium, and their catalytic properties. Cerium-doped bioactive glasses (Ce-BGs) differ in compositions, synthetic methods, features, and in vitro assessment. This review provides an overview on the recent development of Ce-BGs for biomedical applications and on the evaluation of their bioactivity, cytocompatibility, antibacterial, antioxidant, and osteogenic and angiogenic properties as a function of their composition and physicochemical parameters.

Transarterial Radioembolization Agents: a Review of the Radionuclide Agents and the Carriers

Liver tumors, both primary and secondary to metastatic disease, remain a major challenge, with an increasing incidence. In this context, taking advantage of the dual blood supply of the liver, and the fact that liver tumors derive majority of their blood supply from the hepatic artery, intraarterial therapies are gaining popularity. Intraarterial liver-directed therapy (IALDT) is the option when the surgery is not feasible due to the number of metastases or for other reasons. Transarterial radioembolization (TARE) is a specific type of IALDT, where a carrier particle/microsphere is labeled with a radioactive substance and then is injected into hepatic artery for therapeutic purposes. As this field is rapidly evolving, with multiple agents being investigated and being introduced into clinical practice, it is hard for the practitioners and researchers to encompass all the available information concisely. This article aims to present a comprehensive review of the prominent TARE technologies.

Development of Non-Porous Silica Nanoparticles towards Cancer Photo-Theranostics

Nanoparticles have demonstrated several advantages for biomedical applications, including for the development of multifunctional agents as innovative medicine. Silica nanoparticles hold a special position among the various types of functional nanoparticles, due to their unique structural and functional properties. The recent development of silica nanoparticles has led to a new trend in light-based nanomedicines. The application of light provides many advantages for in vivo imaging and therapy of certain diseases, including cancer. Mesoporous and non-porous silica nanoparticles have high potential for light-based nanomedicine. Each silica nanoparticle has a unique structure, which incorporates various functions to utilize optical properties. Such advantages enable silica nanoparticles to perform powerful and advanced optical imaging, from the in vivo level to the nano and micro levels, using not only visible light but also near-infrared light. Furthermore, applications such as photodynamic therapy, in which a lesion site is specifically irradiated with light to treat it, have also been advancing. Silica nanoparticles have shown the potential to play important roles in the integration of light-based diagnostics and therapeutics, termed "photo-theranostics". Here, we review the recent development and progress of non-porous silica nanoparticles toward cancer "photo-theranostics".

Bioactive Glasses: A Promising Therapeutic Ion Release Strategy for Enhancing Wound Healing

The morbidity, mortality, and burden of burn victims and patients with severe diabetic wounds are still high, which leads to an extensively growing demand for novel treatments with high clinical efficacy. Biomaterial-based wound treatment approaches have progressed over time from simple cotton wool dressings to advanced skin substitutes containing cells and growth factors; however, no wound care approach is yet completely satisfying. Bioactive glasses are materials with potential in many areas that exhibit unique features in biomedical applications. Today, bioactive glasses are not only amorphous solid structures that can be used as a substitute in hard tissue but also are promising materials for soft tissue regeneration and wound healing applications. Biologically active elements such as Ag, B, Ca, Ce, Co, Cu, Ga, Mg, Se, Sr, and Zn can be incorporated in glass networks; hence, the superiority of these multifunctional materials over current materials results from their ability to release multiple therapeutic ions in the wound environment, which target different stages of the wound healing process. Bioactive glasses and their dissolution products have high potency for inducing angiogenesis and exerting several biological impacts on cell functions, which are involved in wound healing and some other features that are valuable in wound healing applications, namely hemostatic and antibacterial properties. In this review, we focus on skin structure, the dynamic process of wound healing in injured skin, and existing wound care approaches. The basic concepts of bioactive glasses are reviewed to better understand the relationship between glass structure and its properties. We illustrate the active role of bioactive glasses in wound repair and regeneration. Finally, research studies that have used bioactive glasses in wound healing applications are summarized and the future trends in this field are elaborated.

[Transarterial radioembolization : Immune effects and immuno-oncology]

BACKGROUND

Transarterial radioembolization (TARE) is a locoregional minimally invasive therapeutic strategy to treat primary and secondary hepatic neoplasia.

AIM

The objective was to assess TARE-induced immuno-oncological effects and its perspective for potential therapy improvement by using a combinatory strategy with immune checkpoint inhibitors (ICI).

RESULTS

Yttrium-90 (⁹⁰Y) TARE is used in patients with persisting liver function as the first- and second-line treatment for cholangiocarcinoma and hepatocellular carcinoma and chemotherapy refractory liver metastasis of different primaries. Combination therapy with ⁹⁰Y TARE and ICI may synergistically improve antitumoral immunity and patient outcome. Currently, there are no clinical studies with published data regarding this combination therapy and the subsequently induced immunological effects. Clinical data on other isotopes, e.g., holmium-166 (¹⁶⁶Ho), are also lacking.

CONCLUSION

The clinical evidence of combined treatment with TARE and ICI must be considerably improved. This innovative therapy concept must be studied in new trials assessing the immunological data, including cellular phenotypes, activation, functions, and biomarkers. This may provide valid, sensitive, and specific models in order to evaluate the optimal therapy concept and/or the therapy combination for the best patient outcome.

Glass: Home of the Periodic Table

Glass is the most common material around us, and humankind uses it every day for more than 5000 years. However, from the chemical point of view, glass is the only material that could represent almost all elements of the Periodic Table inside itself, showing the effect of the Periodic Law on properties of the final material. In this paper, we show the most remarkable examples demonstrating that glass can rightfully be called "home" for all chemical elements providing different properties depending on its composition. We gave a new look at the Periodic Table and described how a small number of glass-forming components creates unique glass structure which could enclose almost all remaining elements including transition and noble metals, lanthanides and actinides as modifying components providing an inconceivable number of discoveries in material science. Moreover, we reviewed a series of studies on the direct femtosecond laser writing in glasses which paves the way for a redistribution of chemical elements in the spatially confined nanosized zone in glass volume providing unique properties of laser-induced structures. Finally, for the first time, we reproduce the Periodic Table in birefringence colors in the bulk of silica glass using a direct laser writing technique. This image of 3.6 × 2.4 mm size can withstand temperature up to 900°C, humidity, electromagnetic fields, powerful cosmic and reactor radiation and other environmental factors and demonstrates both the art of direct laser writing and symbolic role of glass as the safest and eternal home for the Periodic Table.

History and development of radioembolization: an old idea with modern applications

The current review documents the major hallmarks in the history and development of radioembolization, the origins of which date back to the late 1940s. Radioembolization was initially abandoned because of the increased incidence of adverse effects and lack of commercial interest; however, it regained avid interest in clinical trials and has achieved established clinical utility in the last 15 years. This review focuses on the main stations of the evolution of radioembolization, namely, initial animal and human experimental studies, production of Y-microspheres, development of current therapeutic agents (resin and glass spheres and labeled Lipiodol), prediction and prevention of inadvertent, extrahepatic shunt side effects, initial prospective studies, and large randomized trials till final approval from the relevant official bodies. The historical knowledge of the initial concepts of the method and the limitations encountered may pave the way toward further evolution and possible new applications.

Synthesis and Preliminary Biological Evaluation of 177Lu-Labeled Polyhydroxamic Acid Microparticles Toward Therapy of Hepatocellular Carcinoma

Background: Transarterial radioembolization (TARE) represents an effective targeted therapeutic option for hepatocellular carcinoma (HCC), a cancer with high mortality and poor prognosis. The aim of this study was the preparation and preliminary biological evaluation of ¹⁷⁷Lu-labeled polyhydroxamic acid (PHA) microparticles toward possible use in the therapy of HCC. Materials and Methods: PHA microparticles were synthesized starting from polyacrylamide. They were characterized by Fourier-transform infrared spectroscopy (FT-IR), visual color test, and laser diffraction particle size analysis. Experimental variables such as reaction pH, amount of PHA microparticles, carrier Lu content, and incubation time were optimized for maximum uptake of ¹⁷⁷Lu on PHA microparticles. Stability of ¹⁷⁷Lu-PHA microparticles was tested in the presence of competing Fe(III) ions in solution. In vitro stability of ¹⁷⁷Lu-PHA microparticles was evaluated in 0.05 M sodium phosphate solution (pH 7.5), saline, and serum. Bioevaluation studies were performed in normal Wistar rats by intrahepatic artery injection of the ¹⁷⁷Lu-PHA microparticles. Results: Successful synthesis of PHA microparticles could be confirmed from the results of FT-IR analysis and visual color test. Laser diffraction-based particle size analysis confirmed median particle size to be 54 μm, suitable for TARE. Under the optimized conditions, >99% loading of ¹⁷⁷Lu on PHA microparticles could be achieved. Even in the presence of high concentration of Fe(III) ions, ¹⁷⁷Lu binding to PHA microparticles was stable. ¹⁷⁷Lu-PHA microparticles exhibited excellent in vitro stability in sodium phosphate solution, saline, and serum up to 5 d at 37°C. In the bioevaluation studies performed in normal Wistar rats, 92.8% ± 3.1% of ¹⁷⁷Lu-PHA microparticles were retained in the liver at 96 h postinjection without any significant leakage to other organs. Conclusion: This preliminary study demonstrates the potential of synthesized PHA microparticles as carriers of therapeutic radioisotopes such as ¹⁷⁷Lu for treatment of HCC.

Glasses for Nuclear Waste Immobilization. Effect of Lutetium Addition on Yttrium Aluminosilicate Glass Crystallization Kinetics

Glasses have emerged as alternative materials that can be used for long-term treatment and management of radioactive waste. Specifically, glasses can be used as a matrix to immobilize the radioactive material. Within the glass industry, silicate glasses are the most widely used due to their properties and to the large knowledge existent about them. Alkaline free silicate glasses are particularly corrosion resistant. Due to the latter, rare earth aluminosilicate glasses are good candidates for actinides immobilization, especially, yttrium aluminosilicate (YAS) glasses. The crystallization kinetics of YAS glasses on heating has been already studied, and this work is focused on the effect of lutetium addition on the YAS glass crystallization kinetics. The presence of a small amount of lutetium in a YAS glass decreases the surface density of nucleation sites (Ns) by about 1 order of magnitude and significantly decreases the crystal growth rate (U). In this work, it was observed that lutetium additions on the order of 0.2 (wt %) to a YAS glass dramatically decreased Ns, for example, at 1000 °C from 1011 to 109 nuclei/m2. Additionally, U for yttrium disilicate phase decreased from (8.21 ± 0.28) μm/h to (0.54 ± 0.04) μm/h at the same temperature.

Control of Dopant Distribution in Yttrium-Doped Bioactive Glass for Selective Internal Radiotherapy Applications Using Spray Pyrolysis

In this study, we demonstrate the fabrication of Y-doped bioactive glass (BG), which is proposed as a potential material for selective internal radiotherapy applications. Owing to its superior bioactivity and biodegradability, it overcomes the problem of yttrium aluminosilicate spheres that remain in the host body for a long duration after treatment. The preparation of Y-doped BG powders were carried out using a spray pyrolysis method. By using two different yttrium sources, we examine the change of the local distribution of yttrium concentration. In addition, characterizations of phase information, particle morphologies, surface areas, and bioactivity were also performed. The results show that both Y-doped BG powders are bioactive and the local Y distribution can be controlled.

Transarterial Radioembolization (TARE) Agents beyond 90Y-Microspheres

Liver malignancies, either primary tumours (mainly hepatocellular carcinoma and cholangiocarcinoma) or secondary hepatic metastases, are a major cause of death, with an increasing incidence. Among them, hepatocellular carcinoma (HCC) presents with a dark prognosis because of underlying liver diseases and an often late diagnosis. A curative surgical treatment can therefore only be proposed in 20 to 30% of the patients. However, new treatment options for intermediate to advanced stages, such as internal radionuclide therapy, seem particularly attractive. Transarterial radioembolization (TARE), which consists in the use of intra-arterial injection of a radiolabelled embolising agent, has led to very promising results. TARE with 90Y-loaded microspheres is now becoming an established procedure to treat liver tumours, with two commercially available products (namely, SIR-Sphere® and TheraSphere®). However, this technology remains expensive and is thus not available everywhere. The aim of this review is to describe TARE alternative technologies currently developed and investigated in clinical trials, with special emphasis on HCC.

Bioactive Glasses: Where Are We and Where Are We Going?

Bioactive glasses caused a revolution in healthcare and paved the way for modern biomaterial-driven regenerative medicine. The first 45S5 glass composition, invented by Larry Hench fifty years ago, was able to bond to living bone and to stimulate osteogenesis through the release of biologically-active ions. 45S5-based glass products have been successfully implanted in millions of patients worldwide, mainly to repair bone and dental defects and, over the years, many other bioactive glass compositions have been proposed for innovative biomedical applications, such as soft tissue repair and drug delivery. The full potential of bioactive glasses seems still yet to be fulfilled, and many of today's achievements were unthinkable when research began. As a result, the research involving bioactive glasses is highly stimulating and requires a cross-disciplinary collaboration among glass chemists, bioengineers, and clinicians. The present article provides a picture of the current clinical applications of bioactive glasses, and depicts six relevant challenges deserving to be tackled in the near future. We hope that this work can be useful to both early-stage researchers, who are moving with their first steps in the world of bioactive glasses, and experienced scientists, to stimulate discussion about future research and discover new applications for glass in medicine.

The development, commercialization, and clinical context of yttrium-90 radiolabeled resin and glass microspheres

Selective internal radiation therapy has emerged as a well-accepted therapeutic for primary and metastatic hepatic malignancies. This therapeutic modality requires the combined efforts of multiple medical disciplines to ensure the safe delivery of yttrium-90 (90Y)-labeled microspheres. The development of this therapy followed decades of clinical research involving tumor vascularity and microsphere development. Today, it is essential that treating physicians have a thorough understanding of hepatic tumor vascularity and 90Y microsphere characteristics before undertaking this complex intervention. This review explores the contributions of early investigators of this therapy, as well as the development, US Food and Drug Administration approval, manufacturing process, and attributes of the 2 commercially available 90Y radiolabeled microsphere device to clarify the key physical differences between the products.

Can C-arm cone-beam CT detect a micro-embolic effect after TheraSphere radioembolization of neuroendocrine and carcinoid liver metastasis?

RATIONAL AND OBJECTIVE

Radioembolization with yttrium-90 microspheres is a therapy that is used for hepatic tumors. 20-30 μm microspheres loaded with Y90 are supposedly occluding tumor vessels at the capillary level. Then, these spheres deliver high-dose radiation to the tumor. However, this theoretical embolic effect has never been appreciated in imaging. Dual-Phase cone-beam computed tomography (DPCBCT) is a multi-phasic intra-procedural scan that uses only one contrast media injection to visualize early (feeding vessel) and delayed (capillary level) tumor enhancement. The purpose of this study was to determine whether there is a micro-embolic effect induced by TheraSpheres® (MDS Nordion, Ottawa, Ontario, Canada) at the capillary level by using DPCBCT imaging.

MATERIALS AND METHODS

14 patients with 72 carcinoid or neuroendocrine tumors were treated with radioembolization, and all underwent DPCBCT (Allura Xper, Philips Healthcare) imaging before and immediately after radioembolization with TheraSpheres®. Tumor enhancement was measured in each phase by drawing a region of interest within the tumors.

RESULTS

72 tumors were evaluated: average tumor density in the early arterial phase was 241 and 230 Hounsfield units (HU) (p<0.001) before and after radioembolization, respectively; the average density in the delayed arterial phase was 226 and 161 HU (p<0.001) before and after radioembolization, respectively. Average difference in tumor attenuation before and after radioembolization in early arterial and delayed phase was 11 HU and 64 HU (p<0.001), respectively.

CONCLUSION

The significant decrease in tumor enhancement in the DPCBCT delayed phase after TheraSpheres® injection indicates that there is an appreciable microembolic effect at the tumor capillary bed level.

Usefulness of Bremsstrahlung Images after Intra-arterial Y-90 Resin Microphere Radioembolization for Hepatic Tumors

PURPOSE

Y-90 resin microsphere radioembolization is used to treat inoperable hepatic tumors. After injection of Y-90 resin microsphere, the only method to visualize the distribution of Y-90 is the scintigraphic imaging of bremsstrahlung radiation. The purpose of this study was to evaluate the characteristics and usefulness of bremsstrahlung imaging in Y-90 resin microsphere treatment.

METHODS

Twenty patients (22 administrations) underwent intra-arterial Y-90 resin microsphere treatment. For pre-treatment planning, images of Tc-99m albumin macroaggregate (MAA) arterial injection and hepatic contrast angiography were obtained. Post-treatment bremsstrahlung images were taken and compared with pre-treatment images. The extrahepatic activity was evaluated on bremsstrahlung images. To correlate the size and vascularity of the tumors with tumor visualization on bremsstrahlung images, the individual tumors were grouped according to visualization on each image and compared with one another by size and tumor-to-normal ratio.

RESULTS

All post-therapeutic bremsstrahlung images showed similar contours of the liver with pre-treatment angiography. No extrahepatic activity was seen in all cases. The visualized tumors on bremsstrahlung images were significantly larger than the non-visualized tumors. Tumor-to-normal ratios of the visualized tumors on bremsstrahlung images were significantly higher than those of the non-visualized tumors.

CONCLUSIONS

Bremsstrahlung images after intra-arterial Y-90 resin microsphere treatment are useful in evaluating the intrahepatic distribution of radioisotope and detecting possible extrahepatic activity.

166Ho-labeled hydroxyapatite particles: a possible agent for liver cancer therapy

PURPOSE

Intra-arterial administration of particulates labeled with -emitting radionuclides is one of the promising modalities for the treatment of liver cancer. 166Ho [T1/2=26.9 hours, E(max) = 1.85 MeV, Egamma = 81keV (6.4%)] could be envisioned as an attractive radionuclide for use in liver cancer therapy owing to its high energy emission, short half-life, and feasibility of its production with adequately high specific activity and radionuclidic purity. Hydroxyapatite (HA) particles in the size range of 20-60 micros were chosen as the particulate carrier due to their biocompatibility and ease of labeling with lanthanides.

METHODS

166Ho was produced by thermal neutron bombardment on a natural holmium target. HA particles of the desired size range were synthesized, characterized, and radiolabeled with 166Ho. The biologic behavior of166Ho-HA was tested in normal Wistar rats by carrying out biodistribution and imaging studies.

RESULTS

166Ho was produced with a specific activity of 5.55-6.48 TBq/g and radionuclidic purity of approximately 100%. HA particles were labeled with 166Ho with a high radiochemical purity of >99% and good in vitro stability up to 7 days. The biodistribution and imaging studies revealed satisfactory hepatic retention (approximately 89% of injected activity after 2 days) with insignificant uptake in any other major organ/tissue.

CONCLUSIONS

166Ho-HA exhibited promising features as an agent for liver cancer therapy in preliminary studies and warrants further investigation

Preparation of 166Ho-oxine-lipiodol and its preliminary bioevaluation for the potential application in therapy of liver cancer

OBJECTIVE

Intra-arterial administration of beta-emitting radionuclides in the form of suitable radiopharmaceuticals is one of the promising modalities for the treatment of liver cancer. Ho [T1/2=26.9 h, Ebeta(max)=1.85 MeV, Egamma=81 keV (6.4%)] could be envisaged as an attractive radionuclide for the use in liver cancer therapy owing to its high-energy beta-emission, short half-life and feasibility of its production with adequately high specific activity and radionuclidic purity using moderate flux reactors. Lipiodol is chosen as the vehicle to deliver localized doses of ionizing radiation to liver cancer cells after intra-arterial hepatic infusion as it is selectively retained in the vascular periphery of the proliferating cells.

METHODS

Ho was produced by thermal neutron bombardment on a natural Ho2O3 target at a flux of approximately 6 x 10 n/cm.s for 7 days. Radiolabelled lipiodol was prepared by dispersing the Ho-oxine complex in lipiodol. The biological behaviour of Ho-oxine-lipiodol was studied by biodistribution and imaging studies in normal Wistar rats.

RESULTS

Ho was produced with a specific activity of 9.25-11.10 TBq/g and radionuclidic purity of approximately 100%. The Ho-labelled oxine complex was prepared in high yield (approximately 97%). Approximately, 95% of the Ho activity was dispersed in lipiodol within 30 min. The resulting radiolabelled preparation was found to exhibit good stability in physiological saline and human serum up to 3 days. The biodistribution and imaging studies revealed satisfactory hepatic retention (88.43+/-2.85% of injected activity after 2 days) with insignificant uptake in any other major organ/tissue except skeleton (6.44+/-1.07% at 2 days postinjection).

CONCLUSION

The Ho-oxine-lipiodol preparation exhibited promising features in preliminary studies and warrants further investigation.

Is selective internal radioembolization safe and effective for patients with inoperable hepatocellular carcinoma and venous thrombosis?

BACKGROUND

The goal of this study was to examine the safety and efficacy of selective internal radioembolization (SIR) for hepatocellular carcinoma (HCC) with portal vein or caval thrombosis (VT), or both. Recent reports have demonstrated that SIR is safe for patients with HCC, but the impact on efficacy of venous thrombosis is unknown.

STUDY DESIGN

Prospective single-arm study of the use of Therasphere in patients with unresectable HCC enrolled from January 2004 to June 2007. Patients were categorized into three groups based on VT status and therapy.

RESULTS

Fifty-two patients were enrolled: 20 patients without VT who received SIR, 15 patients with VT who were treated, and 17 patients (10 with VT) who were not treated because of preprocedure screening failure. Fifty-eight treatments were administered, with a median of two treatments per patient (range of one to three treatments). Child's score was different between groups. Of the VT patients treated, 67% had portal VT, 7% had cava VT, and 26% had both. There were no treatment-related deaths. There was no difference in complications among groups (p = 0.34). Treated patients without thrombosis had a median overall survival of 13.9 months versus 2.7 months for those treated with thrombosis and 5.2 months for the untreated group given best supportive care only (p = 0.01).

CONCLUSIONS

SIR is safe in patients with HCC. Although SIR can be delivered with minimal morbidity, there might be no benefit for patients with VT. Continued emphasis on multimodality therapy in this population is needed to improve survival.

Regional infusion-radioembolization

Selective internal radiation therapy involves the intra-arterial delivery of radioactive beads to the tumor while minimizing dosing to the adjacent organ. Because this technique invariably results in some degree of embolization, it has also been termed radioembolization. More than 8000 patients have been treated worldwide, with a large body of experience with primary hepatocellular carcinoma (HCC) and metastatic colorectal carcinoma (MCRC) and growing experience with other tumors (metastatic neuroendocrine, breast carcinoma, cholangiocarcinoma). Response rates by FDG-PET are 80% to 90%. Complications are uncommon and most often consist of self-limited malaise. More significant complications, including radiation-induced liver disease, ischemic cholecystitis, and gastrointestinal ulceration may be seen in up to 10% of patients. This underscores the critical importance of patient selection and meticulous technique. Median survival times in patients who have HCC and MCRC are significantly improved compared with historic controls. Further study is required to determine the appropriate role of radioembolization in the context of state-of-the-art chemotherapy and other liver-directed therapies.

Preparation and preliminary studies on 177Lu-labeled hydroxyapatite particles for possible use in the therapy of liver cancer

INTRODUCTION

Intra-arterial administration of particulates labeled with suitable beta(-)-emitting radionuclides has emerged as one of the most successful modality for the treatment of primary and metastatic liver cancer. (177)Lu [T(1/2)=6.73 d, E(beta)(max)=0.49 MeV, E(gamma)=208 keV (11%)] could be envisaged as a viable radionuclide for use in liver cancer therapy with wider acceptability owing to its feasibility of production in large-scale and relatively longer half-life providing logistic advantages. Hydroxyapatite (HA) particles of 20-60 microm size range are chosen as the particulate carrier due to its excellent biocompatibility and ease of labeling with lanthanides.

METHODS

(177)Lu was produced by thermal neutron bombardment on enriched Lu target. HA particles of desired size range were synthesized and characterized. Radiolabeling of HA particles was achieved at room temperatures within 30 min. The biological behavior of (177)Lu-labeled HA particles prepared under optimized conditions was tested in Wistar rats.

RESULTS

(177)Lu was produced with a specific activity of 444.2+/-41.8 GBq/mg and radionuclidic purity of 99.98%. (177)Lu-HA was prepared with high radiochemical purity of >99%, and the radiolabeled agent showed excellent in vitro stability. The agent exhibited approximately 73% retention of injected activity in liver after 14 days postadministration with insignificant uptake in any other major organ/tissue except skeleton in biodistribution and imaging studies.

CONCLUSION

(177)Lu-HA exhibited promising features in radiochemical studies. However, preliminary biodistribution studies in normal Wistar rats exhibited suboptimum liver retention and an undesirable skeletal uptake.

Radionuclides delivery systems for nuclear imaging and radiotherapy of cancer

The recent developments of nuclear medicine in oncology have involved numerous investigations of novel specific tumor-targeting radiopharmaceuticals as a major area of interest for both cancer imaging and therapy. The current progress in pharmaceutical nanotechnology field has been exploited in the design of tumor-targeting nanoscale and microscale carriers being able to deliver radionuclides in a selective manner to improve the outcome of cancer diagnosis and treatment. These carriers include chiefly, among others, liposomes, microparticles, nanoparticles, micelles, dendrimers and hydrogels. Furthermore, combining the more recent nuclear imaging multimodalities which provide high sensitivity and anatomical resolution such as PET/CT (positron emission tomography/computed tomography) and SPECT/CT (combined single photon emission computed tomography/computed tomography system) with the use of these specific tumor-targeting carriers constitutes a promising rally which will, hopefully in the near future, allow for earlier tumor detection, better treatment planning and more powerful therapy. In this review, we highlight the use, limitations, advantages and possible improvements of different nano- and microcarriers as potential vehicles for radionuclides delivery in cancer nuclear imaging and radiotherapy.

Resin 90Y-microsphere brachytherapy for unresectable colorectal liver metastases: modern USA experience

PURPOSE

Salvage therapy for patients with unresectable colorectal liver metastases that were refractory to oxaliplatin and irinotecan was performed via radioactive microspheres. High doses of radiation were delivered to tumors from permanently implanted 90Y microspheres, delivered through the hepatic arterial vessels.

METHODS AND MATERIALS

Patients from 7 institutions were selected for treatment after screening-defined vascular access to all the tumors, and imaging-confirmed microspheres would be implanted only in the liver tumors. All patients were followed with laboratory and imaging studies at regular intervals until death. Toxicities, both acute and late, were recorded, and actuarial survival determined.

RESULTS

A total of 208 patients were treated from April 2002 to April 2005. Median follow-up of the 129 men and 79 women is 13 months (range, 1-42 months). Median survival is 10.5 months for responders but only 4.5 months in nonresponders. No treatment-related procedure deaths or radiation-related venoocclusive liver failures were found. Computed tomography partial response was 35%; positron emission tomography response of 91% and reduction in carcinoembryonic antigen of 70% were achieved.

CONCLUSIONS

In this group of heavily pretreated patients, radioactive microspheres produced an encouraging median survival, with acceptable toxicity, and a significant objective response rate, which suggests that further investigation of this approach is warranted.

Radioactive sputter cathodes for 32P plasma-based ion implantation

The development of clinical treatments involving the use of beta-emitting millimetric and sub-millimetric devices has been a continuing trend in nuclear medicine. Implanted a few nanometers below the surface of endovascular implants, seeds or beads, beta-emitting radioisotopes can be used in a variety of biomedical applications. Recently, new technologies have emerged to enable the rapid and efficient activation of such devices. A pulsed, coaxial electron cyclotron resonance plasma reactor was designed and tested to demonstrate the feasibility of plasma-based radioactive ion implantation (PBRII). It has been shown that such plasma reactors allow for the implantation of radioisotopes (32P) into biomedical devices with higher efficiencies than those obtained with conventional ion beams. Fragments containing radioactive atoms are produced in the implanter by means of a negatively biased solid sputter cathode that is inserted into an argon plasma. Dilute orthophosphoric acid solutions (H3(32)PO4) are used for the fabrication of flat sputter targets, since they offer a high radioisotope content. However, the aggregation of the radioactive solute into highly hygroscopic ring-like deposits rather than flat, thin radioactive films is observed on certain substrates. This article describes the effect of this nonuniform distribution of the radioisotopes on the efficiency of PBRII, and presents a technique which enables a better distribution of 32P by coating the substrates with iron. The iron coating is shown to enable optimal radioisotope sputtering rates, which are essential in 32P-PBRII for the efficient activation of millimetric biomedical devices such as stents or coils.

Etiology, screening, and treatment of hepatocellular carcinoma

The prognosis with large hepatocellular carcinomas is poor, and only palliative treatment is available. Small tumors are amenable to several modes of treatment, including liver transplantation, resection, or alcohol injection, with acceptable 5-year survival rates. Although the value of screening for hepatocellular carcinoma has yet to be shown, these data, coupled with the recognition of at-risk groups and useful diagnostic techniques, might encourage the clinician to screen at-risk patients in the clinic. New imaging techniques such as ultrasonographic angiography enhanced with CO2 microbubbles, or color Doppler ultrasound, may clarify the intratumoral blood flow of small tumors.

Iodized oil in the treatment of hepatocellular carcinoma

When injected into the hepatic artery the contrast agent Lipiodol (iodized poppy seed oil) is selectively retained by hepatocellular carcinoma (HCC) for a prolonged period of time. Liver computed tomography (CT) performed after Lipiodol angiography is more sensitive than ordinary CT at imaging HCC. Arterial administration of cytotoxic drugs and radioisotopes conjugated to Lipiodol has been shown to be reasonably safe in patients with irresectable HCC. These therapies, often combined with embolization, provide effective palliation, better tumour response and improved survival compared with other available treatments. Their use as a preoperative adjunct to surgical resection of HCC is controversial.

Poly(L-lactic acid) microspheres containing neutron-activatable holmium-165: a study of the physical characteristics of microspheres before and after irradiation in a nuclear reactor

The solvent evaporation technique was employed to prepare poly(L-lactic acid) (PLA) microspheres with 165Ho acetylacetonate (Ho-AcAc). Particle size, percentage Ho-165, percent residual solvent, and retentive ability of the spheres were found to be strongly affected by preparatory conditions. Differential scanning calorimetry (DSC) thermograms suggested that the Ho-AcAc existed in the PLA matrix as a molecular dispersion. High neutron flux irradiations of the PLA spheres in a nuclear reactor produced Ho-166, a therapeutic radionuclide that emits high-energy negatrons (Emax = 1.84 MeV; half-life = 26.9 hr). The gamma radiation dose (53-75 Mrad) from the core of the reactor provided an overkill of all bioburdens in the PLA spheres. Gel permeation chromatography (GPC) analysis showed that these irradiations caused a reduction in PLA molecular weight. Infrared spectra, 13C NMR spectra, 1H NMR spectra, and DSC thermograms further confirmed the presence of lower molecular weight PLA but proved the overall maintenance of PLA structure.

Radionuclide therapy revisited

Apart from its use in endocrinology and rheumatology, therapeutic nuclear medicine is developing rapidly as an additional treatment modality in oncology. Many different specific tumour-seeking radiopharmaceuticals are being applied both for diagnostic scintigraphy and treatment, using multiple routes and mechanisms to target radionuclides at tumours. After a brief introduction of some basic principles of radionuclide targeting, the therapeutic radiopharmaceuticals available are reviewed according to the accumulation site in relation to the cell nucleus; the results of their current clinical use for therapy are also reviewed. The response observed to a number of these applications, the non-invasiveness of the procedure and the relative lack of toxicity and late effects in comparison with chemotherapy and external beam radiotherapy make radionuclide therapy an attractive and realistic alternative in the management of malignant disease, as well as in the treatment of a few benign disorders.

Natural history of hepatocellular carcinoma and prognosis in relation to treatment. Study of 850 patients

A total of 850 patients with hepatocellular carcinoma seen during the last 8 years were analyzed retrospectively for survival in relation to treatment and disease stage. A new staging scheme based on tumor size, ascites, jaundice and serum albumin was used. Clearly, the prognosis depended on disease stage. The median survival of 229 patients who received no specific treatment was 1.6 months, 0.7 month for Stage III patients, 2.0 months for Stage II, and 8.3 months for Stage I. The median survival of Stage I patients who had hepatic resection (n = 115) was 25.6 months and Stage II patients with resection (n = 42) was 12.2 months. In patients who had a small cancer (less than or equal to 25% of liver area in size) the median survival was 29.0 months. Survival of the surgically treated patients, which represented a highly selected group, was better than that of medically treated patients of a comparable stage. Median survival of Stage I medically treated patients (n = 124) was 9.4 months, for Stage II (n = 290) 3.5 months, and for Stage III (n = 50) 1.6 months. Medical treatment prolonged survival in Stage II and III patients, but not in Stage I. Transcatheter arterial embolization gave a better survival compared with chemotherapy, whether intra-arterial bolus administration of mitomycin C, systemic mitomycin C, or oral/rectal tegafur, in Stage II. Among various chemotherapeutic modalities, intra-arterial bolus injection was superior to systemic chemotherapy in survival in Stage II. In Stage III, chemotherapy improved survival as compared with no specific treatment. The major causes of death were hepatic failure and gastrointestinal bleeding, probably due to the coexistent advanced cirrhosis. These results in survival are much improved over the past reports, and the differences are probably a result of earlier diagnosis and frequent hepatic resections.