Holmium-166 Radioembolization in Hepatocellular Carcinoma: Feasibility and Safety of a New Treatment Option in Clinical Practice

Advances and Emerging Techniques in Y-90 Radioembolization for Hepatocellular Carcinoma

Hepatocellular carcinoma (HCC) is the fourth leading cause of cancer deaths worldwide. Despite the high incidence of HCC, mortality remains high, with an estimated 5-year survival rate of less than 20%. Surgical resection represents a potential curative treatment for HCC; however, less than 20% of patients with HCC are candidates for surgical resection. In patients with unresectable HCC, Yttrium-90 (Y90) transarterial radioembolization (TARE) has emerged as an innovative treatment option. This locoregional therapy delivers high doses of radiation directly to liver tumors via intra-arterial injection, allowing for the targeted destruction of malignant cells while sparing surrounding healthy tissue. In this review, we will explore the latest advances in Y90 TARE for the treatment of HCC, focusing on key developments such as the following: (1) improvements in radiation lobectomy and segmentectomy techniques, (2) the introduction of personalized dosimetry, (3) the integration of combination therapies, (4) the use of imageable microspheres, (5) pressure-enabled Y90 delivery systems, and (6) the application of Y90 surrogates.

166Ho-RadioEmbolizaTiOn Using personalized prediCtive dosimetry in patients with Hepatocellular carcinoma: A prospective, single-centre study (RETOUCH)

BACKGROUND AND AIMS

Holmium-166 (166Ho) radioembolization could offer a more individualized approach in terms of imaging and dosimetry. We aim to evaluate the feasibility and safety of 166Ho selective internal radiation therapy (SIRT) using a higher tumour dose than previously administered determined by 166Ho-scout as a surrogate marker in HCC patients.

METHODS

This is an open-label, prospective, non-randomized, single-centre pilot study that included patients with HCC that received 166Ho-SIRT if the work-up using 166Ho-scout showed a tumour-absorbed dose ≥150 Gy, a non-tumoural liver absorbed dose less than 60 Gy and a lung absorbed dose less than 30 Gy. Primary endpoints were feasibility and safety-toxicity profiles at 24-48 h and 1 month. Overall response rates (ORR) at 3 months (mRECIST, RECIST 1.1 and metabolic response by FDG and choline PET CT) and time to progression (TTP) represented the secondary endpoints.

RESULTS

Fifteen patients with large tumours (mean diameter 55.67 ± 28.42 mm) received 17 166Ho-SIRT treatments between July 2020 and June 2022. All the attempted treatments were accomplished. Mean administered tumour dose was 183.18 ± 71.71 Gy, while non-tumour liver dose was 30.29 ± 14.56 Gy. Median time of follow-up was 12 months (IQR 9-16). Only grade 1-2 clinical and biological AEs were observed. There were no liver decompensations. At 3 months, objective response was achieved for all target lesions (CR 78.57%, PR 21.43% according to mRECIST). Median TTP was 18.8 (range 2.9; n.e.) months.

CONCLUSION

Personalized 166Ho-SIRT with a tumour delivered dose ≥150 Gy was feasible and safe for HCC patients with promising response rates.

Adverse reactions to therapeutic radiopharmaceuticals

Radiopharmaceuticals are drugs used in treatment or diagnosis that contain a radioactive part, usually a pharmaceutical part in their structure. Adverse drug reactions are harmful and unexpected responses that occur when administered at normal doses. Although radiopharmaceuticals are regarded as safe medical products, adverse reactions should not be ignored. More serious adverse reactions such as myelosuppression, pleural effusion, and death may develop in therapeutic radiopharmaceuticals due to their use at higher doses than those used in diagnosis. Therefore, monitoring adverse reactions and reporting them to health authorities is important. This review aims to provide information about adverse reactions that may be related to radiopharmaceuticals used in treatment.

Trends in Selective Internal Radiation Therapy (SIRT) for Treating Hepatocellular Carcinoma, Cholangiocarcinoma, and Liver Metastasis: A Total Population Analysis from 2006 to 2021 in Germany

The aim of this study was to investigate trends in selective internal radiation therapy (SIRT) for hepatocellular carcinoma (HCC), cholangiocarcinoma (CCC), and liver metastasis in Germany. We analyzed the nationwide German hospital billing database from 2006 to 2019 for the diagnosis of HCC, CCC or liver metastasis in combination with SIRT. For analyses of SIRT on the hospital level, we used the reimbursement.INFO tool based on German hospitals' quality reports from 2008 to 2021. Linear regression analysis was performed to detect changes over time. We included a total of 14,165 SIRT procedures. The annual numbers increased from 99 in 2006 to 1605 in 2015 (p < 0.001; increase by 1521%), decreasing to 1175 cases in 2019 (p < 0.001). In 2008, 6 of 21 hospitals (28.6%) performed more than 20 SIRTs per year, which increased to 19 of 53 (35.8%) in 2021. The share of SIRT for HCC increased from 29.8% in 2006 to 44.7% in 2019 (p < 0.001) and for CCC from 0% in 2006 to 9.5% in 2019 (p < 0.001), while the share of SIRT for liver metastasis decreased from 70.2% in 2006 to 45.7% in 2019 (p < 0.001). In-hospital mortality was 0.2% after the SIRT procedure. Gastritis (2.7%), liver failure (0.4%), and sepsis (0.3%) were the most common in-hospital complications reported. We observed an increase in SIRT procedures in Germany, with the number of hospitals offering the procedure going up from 21 in 2008 to 53 in 2021. While the treatment of liver metastasis remains the most common indication, SIRT for HCC and CCC increased significantly over the last few years. The mortality and complication rates show that SIRT is a relatively safe procedure.

Locoregional Therapy for Intrahepatic Cholangiocarcinoma: The Role of Intra-Arterial Therapies

Intrahepatic cholangiocarcinoma (ICC) is a rare disease with a rising incidence. While surgical resection is the only curative option, the disease process is often identified in advanced stages, as this malignancy often remains clinically silent in early development. Only one-third of patients are eligible for resection at the time of diagnosis. For patients who cannot undergo resection, intra-arterial therapies are reasonable palliative treatment options; in rare occasions, these may be bridging therapies, as well. The premise of bland embolization and most chemoembolization intra-arterial therapies is that the arterial supply of the tumor is occluded to induce tumor necrosis, while radioembolization utilizes the arterial flow of the tumor to deliver radiation therapy. In this review, we discuss the use of transarterial embolization, transarterial chemoembolization, and selective internal radiation therapy for the treatment of ICC. Phase III randomized controlled clinical trials are difficult to tailor to this extremely rare and aggressive disease, but ultimately, further investigation should be pursued to define the patient population that will derive the greatest benefit from each modality.

Microfluidic Controllable Preparation of Iodine-131-Labeled Microspheres for Radioembolization Therapy of Liver Tumors

Transcatheter arterial radioembolization (TARE) is of great significance for the treatment of advanced hepatocellular carcinoma (HCC). However, the existing radioembolic microspheres still have problems such as non-degradability, non-uniform size, and inability to directly monitor in vivo, which hinders the development of TARE. In this paper, a novel radioembolic agent, 131 I-labeled methacrylated gelatin microspheres (131 I-GMs), is prepared for the treatment of HCC. Water-in-oil (W/O) emulsion templates are prepared by a simple one-step microfluidic method to obtain methacrylated gelatin microspheres (GMs) after UV irradiation. A series of GMs with uniform and controllable size is obtained by adjusting the flow rate of each fluid. Both air-dried and freeze-dried GMs can quickly restore their original shape and size, and still have good monodispersity, elasticity, and biocompatibility. The radiolabeling experiments show that 131 I can efficiently bind to GMs by chloramine-T method, and the obtained 131 I-GMs have good radioactive stability in vitro. The results of in vivo TARE treatment in rats show that 131 I-GMs can be well retained in the hepatic artery and have a good inhibitory effect on the progression of liver cancer, showing the potential for the treatment of HCC.

Recent Advances in Locoregional Therapy of Hepatocellular Carcinoma

Hepatocellular carcinoma (HCC) is responsible for 90% of primary hepatic cancer cases, and its incidence with associated morbidity and mortality is growing worldwide. In recent decades, there has been a revolution in HCC treatment. There are three main types of locoregional therapy: radiofrequency ablation, transarterial chemoembolisation, and transarterial radioembolisation. This article summarises recent advances in locoregional methods.

Clinical Results of Transarterial Radioembolization (TARE) with Holmium-166 Microspheres in the Multidisciplinary Oncologic Treatment of Patients with Primary and Secondary Liver Cancer

Holmium-166 microspheres are used for the transarterial radioembolization (TARE) treatment of primary and secondary liver cancers. In this study, its efficacy regarding local tumor control and integration into the oncological treatment sequence of the first 20 patients treated in our institution were examined. A total of twenty-nine 166Ho-TARE procedures were performed to treat hepatocellular carcinoma (HCC, fourteen patients), metastatic colorectal cancer (mCRC, four patients), intrahepatic cholangiocarcinoma (ICC, one patient), and hemangioendothelioma of the liver (HE, one patient). In eight patients, 166Ho-TARE was the initial oncologic treatment. In patients with HCC, the median treated-liver progression-free survival (PFS), overall PFS, and overall survival after 166Ho-TARE were 10.3, 7.3, and 22.1 months; in patients with mCRC, these were 2.6, 2.9, and 20.6 months, respectively. Survival after 166Ho-TARE in the patients with ICC and HE were 5.2 and 0.8 months, respectively. Two patients with HCC were bridged to liver transplantation, and one patient with mCRC was downstaged to curative surgery. In patients with HCC, a median treatment-free interval of 7.3 months was achieved. In line with previous publications, 166Ho-TARE was a feasible treatment option in patients with liver tumors, with favorable clinical outcomes in the majority of cases. It was able to achieve treatment-free intervals, served as bridging-to-transplant, and did not prevent subsequent therapies.

The Synergistic Effect of Interventional Locoregional Treatments and Immunotherapy for the Treatment of Hepatocellular Carcinoma

Immunotherapy has remarkably revolutionized the management of advanced HCC and prompted clinical trials, with therapeutic agents being used to selectively target immune cells rather than cancer cells. Currently, there is great interest in the possibility of combining locoregional treatments with immunotherapy for HCC, as this combination is emerging as an effective and synergistic tool for enhancing immunity. On the one hand, immunotherapy could amplify and prolong the antitumoral immune response of locoregional treatments, improving patients' outcomes and reducing recurrence rates. On the other hand, locoregional therapies have been shown to positively alter the tumor immune microenvironment and could therefore enhance the efficacy of immunotherapy. Despite the encouraging results, many unanswered questions still remain, including which immunotherapy and locoregional treatment can guarantee the best survival and clinical outcomes; the most effective timing and sequence to obtain the most effective therapeutic response; and which biological and/or genetic biomarkers can be used to identify patients likely to benefit from this combined approach. Based on the current reported evidence and ongoing trials, the present review summarizes the current application of immunotherapy in combination with locoregional therapies for the treatment of HCC, and provides a critical evaluation of the current status and future directions.

Intraprocedural MRI-based dosimetry during transarterial radioembolization of liver tumours with holmium-166 microspheres (EMERITUS-1): a phase I trial towards adaptive, image-controlled treatment delivery

PURPOSE

Transarterial radioembolization (TARE) is a treatment for liver tumours based on injection of radioactive microspheres in the hepatic arterial system. It is crucial to achieve a maximum tumour dose for an optimal treatment response, while minimizing healthy liver dose to prevent toxicity. There is, however, no intraprocedural feedback on the dose distribution, as nuclear imaging can only be performed after treatment. As holmium-166 (¹⁶⁶Ho) microspheres can be quantified with MRI, we investigate the feasibility and safety of performing ¹⁶⁶Ho TARE within an MRI scanner and explore the potential of intraprocedural MRI-based dosimetry.

METHODS

Six patients were treated with ¹⁶⁶Ho TARE in a hybrid operating room. Per injection position, a microcatheter was placed under angiography guidance, after which patients were transported to an adjacent 3-T MRI system. After MRI confirmation of unchanged catheter location, ¹⁶⁶Ho microspheres were injected in four fractions, consisting of 10%, 30%, 30% and 30% of the planned activity, alternated with holmium-sensitive MRI acquisition to assess the microsphere distribution. After the procedures, MRI-based dose maps were calculated from each intraprocedural image series using a dedicated dosimetry software package for ¹⁶⁶Ho TARE.

RESULTS

Administration of ¹⁶⁶Ho microspheres within the MRI scanner was feasible in 9/11 (82%) injection positions. Intraprocedural holmium-sensitive MRI allowed for tumour dosimetry in 18/19 (95%) of treated tumours. Two CTCAE grade 3-4 toxicities were observed, and no adverse events were attributed to treatment in the MRI. Towards the last fraction, 4/18 tumours exhibited signs of saturation, while in 14/18 tumours, the microsphere uptake patterns did not deviate from the linear trend.

CONCLUSION

This study demonstrated feasibility and preliminary safety of a first in-human application of TARE within a clinical MRI system. Intraprocedural MRI-based dosimetry enabled dynamic insight in the microsphere distribution during TARE. This proof of concept yields unique possibilities to better understand microsphere distribution in vivo and to potentially optimize treatment efficacy through treatment personalization.

REGISTRATION

Clinicaltrials.gov, identifier NCT04269499, registered on February 13, 2020 (retrospectively registered).

Holmium-166 Radioembolization: Current Status and Future Prospective

Since its first suggestion as possible option for liver radioembolization treatment, the therapeutic isotope holmium-166 (¹⁶⁶Ho) caught the experts’ attention due to its imaging possibilities. Being not only a beta, but also a gamma emitter and a lanthanide, ¹⁶⁶Ho can be imaged using single-photon emission computed tomography and magnetic resonance imaging, respectively. Another advantage of ¹⁶⁶Ho is the possibility to perform the scout and treatment procedure with the same particle. This prospect paves the way to an individualized treatment procedure, gaining more control over dosimetry-based patient selection and treatment planning. In this review, an overview on ¹⁶⁶Ho liver radioembolization will be presented. The current clinical workflow, together with the most relevant clinical findings and the future prospective will be provided.

Availability of Interventional Oncology in Germany in the Years 2018 and 2019 - Results from a Nationwide Database (DeGIR Registry Data)

OBJECTIVE

 Over the past few decades, radiology has established itself in tumor therapy through interventional oncology including innovative and efficient procedures for minimalinvasive treatment of various tumor entities besides the "classic" therapeutic options such as surgery, chemotherapy and radiotherapy.Aim of this study was to evaluate the extent to which interventional oncology can provide nationwide care using the data from the register of the German Society for Interventional Radiology and Minimally Invasive Therapy (DeGIR registry), which records radiological interventions as part of quality assurance.

METHODS

 The numbers of interventions of participating clinics, which were recorded as part of module D (oncological procedures including TACE or other tumor-specific embolization, ablation, percutaneous tumor therapy) and identified by the DeGIR registry between 2018 and 2019, were analyzed retrospectively. The collected intervention data were evaluated regarding federal states and 40 smaller regions (administrative districts and former administrative districts).

RESULTS

 In 2018, 11 653 oncological interventions in 187 clinics were recorded by the DeGIR registry. In 2019, the number of participating clinics rose to 216 and the number of oncological interventions increased by 6 % to 12 323. The average number of oncological interventions per clinic decreased slightly from 62.5 (2018) to 57.1 (2019). The DeGIR requirement for being certified as a training center was met by 116 clinics in 2018 including 31 clinics with more than 100 interventions and 129 clinics in 2019 including 36 with more than 100 interventions. Oncological interventions have been performed in each of the 40 regions. An average of 599 interventions per region (standard deviation of 414) was recorded in the period between 2018 and 2019.

CONCLUSION

 Based on the distribution of the documented oncological interventions at federal state level as well as the district level, the supply of interventional tumor therapy depends on the geographical location. Therefore, the demand of oncological interventions might not be sufficiently covered in some regions.

KEY POINTS

· Interventional-oncological tumor therapies are performed throughout Germany. · Looking at the notable geographical differences, the need for interventional oncological procedures does not seem to be sufficiently met.. · In order to improve the comprehensive provision of oncological interventions, the training of interventional radiologists should be promoted further..

CITATION FORMAT

· Radosa CG, Nadjiri J, Mahnken AH et al. Availability of Interventional Oncology in Germany in the Years 2018 and 2019 - Results from a Nationwide Database (DeGIR Registry Data). Fortschr Röntgenstr 2022; DOI: 10.1055/a-1729-0951.

TARE in Hepatocellular Carcinoma: From the Right to the Left of BCLC

The Barcelona Clinic Liver Cancer (BCLC) system is the most commonly used staging system for hepatocellular carcinoma (HCC) in Western countries. BCLC aims to categorize patients into five stages with different prognoses and to allocate treatment according to these stages based on the best possible contemporary evidence. Transarterial radioembolization (TARE) has recently entered at the left of the BCLC algorithm (i.e., BCLC 0-A), mainly because of negative phase III trials in BCLC C stage. TARE has shown a steady increase in nationwide studies over the past 20 years and has even been adopted in some tertiary centers as the primary HCC treatment across all BCLC stages. We aimed to review the history of TARE in HCC, starting from advanced HCC and gradually expanding to earlier stages at the left of the BCLC system.

SIRT in 2025

Selective internal radiation therapy represents an endovascular treatment option for patients with primary liver malignancies, in different clinical stages. Potential applications of this treatment are in early-stage hepatocellular carcinoma, as a curative option, or in combination with systemic treatments in intermediate and advanced-stages. This review, based on existing literature and ongoing trials, will focus on the future of this treatment in patients with hepatocellular carcinoma, in combination with systemic treatments, or with the use of new devices and technological developments; it will also describe new potential future indications and structural and organizational perspectives.

Theragnostics in primary and secondary liver tumors: the need for a personalized approach

Primary and secondary hepatic tumors have a dramatic impact in oncology. Despite many advances in diagnosis and therapy, the management of hepatic malignancies is still challenging, ranging from various loco-regional approaches to system therapies. In this scenario, theragnostic approaches, based on the administration of a radiopharmaceuticals' pair, the first labeled with a radionuclide suitable for the diagnostic phase and the second one bound to radionuclide emitting particles for therapy, is gaining more and more importance. Selective internal radiation therapy (SIRT) with microspheres labeled with ⁹⁰Y or ¹⁶⁶Ho is widely used as a loco-regional treatment for primary and secondary hepatic tumors. While ¹⁶⁶Ho presents both gamma and beta emission and can be therefore considered a real "theragnostic" agent, for ⁹⁰Y-microspheres theragnostic approach is realized at the diagnostic phase through the utilization of macroaggregates of human albumin, labeled with ^99mTc as "biosimilar" agent respect to microspheres. The aim of the present review was to cover theragnostic applications of ⁹⁰Y/¹⁶⁶Ho-labeled microspheres in clinical practice. Furthermore, we report the preliminary data concerning the potential role of some emerging theragnostic biomarkers for hepatocellular carcinoma, such as glypican-3 (GPC3) and prostate specific membrane antigen (PSMA).

Locoregional Treatments for Bridging and Downstaging HCC to Liver Transplantation

Liver transplantation (LT) is the first-line treatment for patients diagnosed with unresectable early-stage hepatocellular carcinoma (HCC) in the setting of cirrhosis. It is well known that HCC patients within the Milan criteria (solitary tumour ≤ 5 cm or ≤3 tumours, each <3 cm) could undergo LT with excellent results. However, there is a growing tendency to enlarge inclusion criteria since the Milan criteria are nowadays considered too restrictive and may exclude patients who would benefit from LT. On the other hand, there is a persistent shortage of donor organs. In this scenario, there is consensus about the role of loco-regional therapy (LRT) during the waiting list to select patients who would benefit more from LT, reducing the risk of drop off from the waiting list as well as decreasing tumour dimension to meet acceptable criteria for LT. In this review, current evidence on the safety, efficacy and utility of LRTs as neoadjuvant therapies before LT are summarized.

Development of an MRI-Guided Approach to Selective Internal Radiation Therapy Using Holmium-166 Microspheres

Simple Summary

Selective internal radiation therapy (SIRT) is a treatment for patients with liver cancer that involves the injection of radioactive microspheres into the liver artery. For a successful treatment, it is important that tumours are adequately covered with these microspheres; however, there is currently no method to assess this intraoperatively. As holmium microspheres are paramagnetic, MRI can be used to visualize the holmium deposition directly after administration, and possibly to adapt the treatment if necessary. In order to exploit this advantage and provide a personally optimized approach to SIRT, the administration could ideally be performed within a clinical MRI scanner. It is, however, unclear whether all materials (catheters, administration device) used during the procedure are safe for use in the MRI suite. Additionally, we explore the capability of MRI to visualize the microspheres in near real-time during injection, which would be a requirement for successful MRI-guided treatment. We further illustrate our findings with an initial patient case.

Abstract

Selective internal radiation therapy (SIRT) is a treatment modality for liver tumours during which radioactive microspheres are injected into the hepatic arterial tree. Holmium-166 (¹⁶⁶Ho) microspheres used for SIRT can be visualized and quantified with MRI, potentially allowing for MRI guidance during SIRT. The purpose of this study was to investigate the MRI compatibility of two angiography catheters and a microcatheter typically used for SIRT, and to explore the detectability of ¹⁶⁶Ho microspheres in a flow phantom using near real-time MRI. MR safety tests were performed at a 3 T MRI system according to American Society for Testing of Materials standard test methods. To assess the near real-time detectability of ¹⁶⁶Ho microspheres, a flow phantom was placed in the MRI bore and perfused using a peristaltic pump, simulating the flow in the hepatic artery. Dynamic MR imaging was performed using a 2D FLASH sequence during injection of different concentrations of ¹⁶⁶Ho microspheres. In the safety assessment, no significant heating (ΔT_max 0.7 °C) was found in any catheter, and no magnetic interaction was found in two out of three of the used catheters. Near real-time MRI visualization of ¹⁶⁶Ho microsphere administration was feasible and depended on holmium concentration and vascular flow speed. Finally, we demonstrate preliminary imaging examples on the in vivo catheter visibility and near real-time imaging during ¹⁶⁶Ho microsphere administration in an initial patient case treated with SIRT in a clinical 3 T MRI. These results support additional research to establish the feasibility and safety of this procedure in vivo and enable the further development of a personalized MRI-guided approach to SIRT.

Unresectable hepatocellular carcinoma treatment with doxorubicin-eluting polyethylene glycol microspheres: a single-center experience

Background

Transarterial chemoembolization (TACE) is indicated for unresectable hepatocellular carcinoma.

Methods

This was a retrospective study of 50 hepatocellular carcinoma patients treated with TACE using doxorubicin-loaded LifePearl™ to investigate the safety and efficacy of TACE.

Results

There was no 30-day mortality, and limited adverse events were reported. At best tumor response, complete response and disease control were 58% and 94%, respectively, with a median of 4.5 months of follow-up. Median overall survival was 33.8 months. Patients with Barcelona Clinic Liver Cancer stage 0 and stage A at best tumor response showed a higher complete response rate (83%) than patients with Barcelona Clinic Liver Cancer stage B (complete response: 50%; p = 0.0414).

Conclusion

Doxorubicin-loaded LifePearl™ TACE might be an effective treatment, with a good safety profile, for patients with early/intermediate-stage hepatocellular carcinoma. Further prospective data, especially with a small cohort of selected patients, are required to confirm these results.

Role of Radioembolization in the Management of Liver-Dominant Metastatic Renal Cell Carcinoma: A Single-Center, Retrospective Study

PURPOSE

The management of Renal cell carcinoma (RCC) patients with liver metastases is challenging. Liver-directed therapy, such as Transarterial radioembolization (TARE), is a reasonable option for these patients; however, its safety and efficacy are not well characterized. This study evaluated the safety and efficacy of TARE in patients with liver-dominant metastatic RCC.

MATERIALS AND METHODS

This is a retrospective, single-center study. Thirty-eight patients' medical records were reviewed who underwent TARE between January 1, 2009, and December 31, 2019, in a tertiary cancer center. Two were excluded from further analysis. Thirty-six patients received 51 TARE treatments. Median follow-up time was 18.2 months. Imaging data were evaluated using mRECIST or RECIST 1.1 criteria. Toxicities, treatment responses, liver progression-free survival (LPFS), and median overall survival (OS) were calculated. Univariate and multivariate analyses were conducted to reveal predictors of OS.

RESULTS

Median OS from TARE was 19.3 months (95% CI, 22.6-47.4) and from diagnosis of liver metastases was 36.5 months (95% CI: 26.4-49.8). Mild, grade 1 or 2, biochemical toxicity developed in 27 patients (75%). Grade 3-4 toxicity was noted in two patients (5.5%). The objective response rate was 89%; the disease control rate was 94% (21 complete response, 11 partial response, two stable disease, and two progressive disease). Univariate and multivariate analyses showed longer survival in patients who had objective response, lower lung shunt fraction, and better baseline liver function.

CONCLUSIONS

TARE is safe and effective and led to promising overall survival in patients with liver-dominant metastatic RCC.

LEVEL OF EVIDENCE

Level 3, retrospective cohort study.

Microspheres Used in Liver Radioembolization: From Conception to Clinical Effects

Inert microspheres, labeled with several radionuclides, have been developed during the last two decades for the intra-arterial treatment of liver tumors, generally called Selective Intrahepatic radiotherapy (SIRT). The aim is to embolize microspheres into the hepatic capillaries, accessible through the hepatic artery, to deliver high levels of local radiation to primary (such as hepatocarcinoma, HCC) or secondary (metastases from several primary cancers, e.g., colorectal, melanoma, neuro-endocrine tumors) liver tumors. Several types of microspheres were designed as medical devices, using different vehicles (glass, resin, poly-lactic acid) and labeled with different radionuclides, 90Y and 166Ho. The relationship between the microspheres' properties and the internal dosimetry parameters have been well studied over the last decade. This includes data derived from the clinics, but also computational data with various millimetric dosimetry and radiobiology models. The main purpose of this paper is to define the characteristics of these radiolabeled microspheres and explain their association with the microsphere distribution in the tissues and with the clinical efficacy and toxicity. This review focuses on avenues to follow in the future to optimize such particle therapy and benefit to patients.

To 1000 Gy and back again: a systematic review on dose-response evaluation in selective internal radiation therapy for primary and secondary liver cancer

Purpose

To systematically review all current evidence into the dose-response relation of yttrium-90 and holmium-166 selective internal radiation therapy (SIRT) in primary and secondary liver cancer.

Methods

A standardized search was performed in PubMed (MEDLINE), Embase, and the Cochrane Library in order to identify all published articles on dose-response evaluation in SIRT. In order to limit the results, all articles that investigated SIRT in combination with other therapy modalities (such as chemotherapy) were excluded.

Results

A total of 3038 records were identified of which 487 were screened based on the full text. Ultimately, 37 studies were included for narrative analysis. Meta-analysis could not be performed due to the large heterogeneity in study and reporting designs. Out of 37 studies, 30 reported a ‘mean dose threshold’ that needs to be achieved in order to expect a response. This threshold appears to be higher for hepatocellular carcinoma (HCC, 100–250 Gy) than for colorectal cancer metastases (CRC, 40–60 Gy). Reported thresholds tend to be lower for resin microspheres than when glass microspheres are used.

Conclusion

Although the existing evidence demonstrates a dose-response relationship in SIRT for both primary liver tumours and liver metastases, many pieces of the puzzle are still missing, hampering the definition of standardized dose thresholds. Nonetheless, most current evidence points towards a target mean dose of 100–250 Gy for HCC and 40–60 Gy for CRC. The field would greatly benefit from a reporting standard and prospective studies designed to elucidate the dose-response relation in different tumour types.

Supplementary Information

The online version contains supplementary material available at 10.1007/s00259-021-05340-0.

Selective internal radiation therapies for unresectable early-, intermediate- or advanced-stage hepatocellular carcinoma: systematic review, network meta-analysis and economic evaluation

BACKGROUND

Hepatocellular carcinoma is the most common type of primary liver cancer. Treatment choice is dependent on underlying liver dysfunction and cancer stage. Treatment options include conventional transarterial therapies for patients with intermediate-stage disease and systemic therapy [e.g. sorafenib (Nexavar®; Bayer plc, Leverkusen, Germany)] for patients with advanced-stage disease. Selective internal radiation therapies deliver radiation to liver tumours via microspheres that are injected into the hepatic artery. There are three selective internal radiation therapies: TheraSphere™ [BTG Ltd, London, UK (now Boston Scientific, Marlborough, MA, USA)], SIR-Spheres® (Sirtex Medical Ltd, Woburn, MA, USA) and QuiremSpheres® (Quirem Medical BV, Deventer, the Netherlands).

OBJECTIVE

To assess the clinical effectiveness and cost-effectiveness of selective internal radiation therapies for treating patients with unresectable early-, intermediate- or advanced-stage hepatocellular carcinoma.

METHODS

A search was undertaken to identify clinical effectiveness literature relating to selective internal radiation therapies and relevant comparators for the treatment of hepatocellular carcinoma. Studies were critically appraised and summarised. The network of evidence was mapped to estimate the relative effectiveness of the different selective internal radiation therapies and comparator treatments. An economic analysis evaluated the cost-effectiveness.

RESULTS

Twenty studies were included in the clinical effectiveness review. Two large randomised controlled trials rated as having a low risk of bias [SARAH: Vilgrain V, Pereira H, Assenat E, Guiu B, Ilonca AD, Pageaux GP, et al. Efficacy and safety of selective internal radiotherapy with yttrium-90 resin microspheres compared with sorafenib in locally advanced and inoperable hepatocellular carcinoma (SARAH): an open-label randomised controlled Phase 3 trial. Lancet Oncol 2017;18:1624-36; and SIRveNIB: Chow PKH, Gandhi M, Tan SB, Khin MW, Khasbazar A, Ong J, et al. SIRveNIB: selective internal radiation therapy versus sorafenib in Asia-Pacific patients with hepatocellular carcinoma. J Clin Oncol 2018;36:1913-21] found no significant difference in overall survival or progression-free survival between SIR-Spheres and sorafenib (systemic therapy) in an advanced population, despite greater tumour response in the SIR-Spheres arm of both trials. There were some concerns regarding generalisability of the SARAH and SIRveNIB trials to UK practice. All other studies of SIR-Spheres, TheraSphere or QuiremSpheres were either rated as being at a high risk of bias or caused some concerns regarding bias. A network meta-analysis was conducted in adults with unresectable hepatocellular carcinoma who had Child-Pugh class A liver cirrhosis and were ineligible for conventional transarterial therapies. The analysis included the SARAH and SIRveNIB trials as well as a trial comparing lenvatinib (Kisplyx®; Eisai Ltd, Tokyo, Japan) (systemic therapy) with sorafenib. There were no meaningful differences in overall survival between any of the treatments. The base-case economic analysis suggested that TheraSphere may be cost-saving relative to both SIR-Spheres and QuiremSpheres. However, incremental cost differences between TheraSphere and SIR-Spheres were small. In a fully incremental analysis, which included confidential Patient Access Scheme discounts, lenvatinib was the most cost-effective treatment and dominated all selective internal radiation therapies. In pairwise comparisons of sorafenib with each selective internal radiation therapy, sorafenib also dominated all selective internal radiation therapies.

LIMITATIONS

The existing evidence cannot provide decision-makers with clear guidance on the comparative effectiveness of treatments in early- and intermediate-stage hepatocellular carcinoma or on the efficacy of TheraSphere or QuiremSpheres.

CONCLUSIONS

In the advanced-stage hepatocellular carcinoma population, two large randomised trials have shown that SIR-Spheres have similar clinical effectiveness to sorafenib. None of the selective internal radiation therapies was cost-effective, being more costly and less effective than lenvatinib, both at list price and with Patient Access Scheme discounts.

FUTURE WORK

Future studies may wish to include early- and intermediate-stage hepatocellular carcinoma patients and the low tumour burden/albumin-bilirubin 1 subgroup of advanced-stage patients. Future high-quality studies evaluating alternative selective internal radiation therapies would be beneficial.

STUDY REGISTRATION

This study is registered as PROSPERO CRD42019128383.

FUNDING

This project was funded by the National Institute for Health Research (NIHR) Health Technology Assessment programme and will be published in full in Health Technology Assessment; Vol. 24, No. 48. See the NIHR Journals Library website for further project information.

Methods for selecting the best evidence to inform a NICE technology appraisal on selective internal radiation therapies for hepatocellular carcinoma

BACKGROUND

Systematic reviews of medical devices are particularly challenging as the quality of evidence tends to be more limited than evidence on pharmaceutical products. This article describes the methods used to identify, select and critically appraise the best available evidence on selective internal radiation therapy devices for treating hepatocellular carcinoma, to inform a technology appraisal for the National Institute for Health and Care Excellence.

METHODS

A comprehensive search of ten medical databases and six grey literature sources was undertaken to identify studies of three devices (TheraSphere®, SIR-Spheres® and QuiremSpheres®) for treating hepatocellular carcinoma. The large evidence base was scoped before deciding what level of evidence to include for data extraction and critical appraisal. The methodological quality of the included studies was assessed using criteria relevant to each study design.

RESULTS

Electronic searches identified 4755 records; over 1000 met eligibility criteria after screening titles and abstracts. A hierarchical process was used to scope these records, prioritising comparative studies over non-comparative studies, where available. One hundred ninety-four full papers were ordered; 64 met the eligibility criteria. For each intervention, studies were prioritised by study design and applicability to current UK practice, resulting in 20 studies subjected to critical appraisal and data extraction. Only two trials had a low overall risk of bias. In view of the poor quality of the research evidence, our technology appraisal focused on the two higher quality trials, including a thorough critique of their reliability and generalisability to current UK practice. The 18 poorer quality studies were briefly summarised; many were very small and results were often contradictory. No definitive conclusions could be drawn from the poorer quality research evidence available.

CONCLUSIONS

A systematic, pragmatic process was used to select and critically appraise the vast quantity of research evidence available in order to present the most reliable evidence on which to develop recommendations.

SYSTEMATIC REVIEW REGISTRATION

PROSPERO CRD42019128383.

Neutron Activated 153Sm Sealed in Carbon Nanocapsules for in Vivo Imaging and Tumor Radiotherapy

Radiation therapy along with chemotherapy and surgery remain the main cancer treatments. Radiotherapy can be applied to patients externally (external beam radiotherapy) or internally (brachytherapy and radioisotope therapy). Previously, nanoencapsulation of radioactive crystals within carbon nanotubes, followed by end-closing, resulted in the formation of nanocapsules that allowed ultrasensitive imaging in healthy mice. Herein we report on the preparation of nanocapsules initially sealing "cold" isotopically enriched samarium (152Sm), which can then be activated on demand to their "hot" radioactive form (153Sm) by neutron irradiation. The use of "cold" isotopes avoids the need for radioactive facilities during the preparation of the nanocapsules, reduces radiation exposure to personnel, prevents the generation of nuclear waste, and evades the time constraints imposed by the decay of radionuclides. A very high specific radioactivity is achieved by neutron irradiation (up to 11.37 GBq/mg), making the "hot" nanocapsules useful not only for in vivo imaging but also therapeutically effective against lung cancer metastases after intravenous injection. The high in vivo stability of the radioactive payload, selective toxicity to cancerous tissues, and the elegant preparation method offer a paradigm for application of nanomaterials in radiotherapy.

Current outlook on radionuclide delivery systems: from design consideration to translation into clinics

Radiopharmaceuticals have proven to be effective agents, since they can be successfully applied for both diagnostics and therapy. Effective application of relevant radionuclides in pre-clinical and clinical studies depends on the choice of a sufficient delivery platform. Herein, we provide a comprehensive review on the most relevant aspects in radionuclide delivery using the most employed carrier systems, including, (i) monoclonal antibodies and their fragments, (ii) organic and (iii) inorganic nanoparticles, and (iv) microspheres. This review offers an extensive analysis of radionuclide delivery systems, the approaches of their modification and radiolabeling strategies with the further prospects of their implementation in multimodal imaging and disease curing. Finally, the comparative outlook on the carriers and radionuclide choice, as well as on the targeting efficiency of the developed systems is discussed.

The various therapeutic applications of the medical isotope holmium-166: a narrative review

Over the years, a broad spectrum of applications of the radionuclide holmium-166 as a medical isotope has been established. The isotope holmium-166 is attractive as it emits high-energy beta radiation which can be used for a therapeutic effect and gamma radiation which can be used for nuclear imaging purposes. Furthermore, holmium-165 can be visualized by MRI because of its paramagnetic properties and by CT because of its high density. Since holmium-165 has a natural abundance of 100%, the only by-product is metastable holmium-166 and no costly chemical purification steps are necessary for production of nuclear reactor derived holmium-166. Several compounds labelled with holmium-166 are now used in patients, such Ho¹⁶⁶-labelled microspheres for liver malignancies, Ho¹⁶⁶-labelled chitosan for hepatocellular carcinoma (HCC) and [¹⁶⁶Ho]Ho DOTMP for bone metastases. The outcomes in patients are very promising, making this isotope more and more interesting for applications in interventional oncology. Both drugs as well as medical devices labelled with radioactive holmium are used for internal radiotherapy. One of the treatment possibilities is direct intratumoural treatment, in which the radioactive compound is injected with a needle directly into the tumour. Numerous other applications have been developed, like patches for treatment of skin cancer and holmium labelled antibodies and peptides. The second major application that is currently clinically applied is selective internal radiation therapy (SIRT, also called radioembolization), a novel treatment option for liver malignancies. This review discusses medical drugs and medical devices based on the therapeutic radionuclide holmium-166.