Radioembolization with yttrium-90 resin microspheres for neuroendocrine tumor liver metastases

New frontiers in radioembolization

Radioembolization is a locoregional transarterial therapy that combines radionuclide and micron-sized beads to deliver radiation internally to the target tumors based on the arterial blood flow. While initially developed as a palliative treatment option, radioembolization is now used for curative intent treatment, neoadjuvant therapy, and method to downstage or bridge for liver transplant. Radioembolization has become increasingly utilized and is an important therapeutic option for the management of hepatocellular carcinoma and liver metastasis. This article provides an overview of the techniques, challenges, and novel developments in radioembolization, including new dosimetry techniques, radionuclides, and new target tumors.

Neuroendocrine liver metastases treated using transarterial radioembolization: Identification of prognostic parameters at 68Ga-DOTATATE PET/CT

PURPOSE

To identify prognostic clinical and imaging parameters for patients with neuroendocrine liver metastases (NELMs) undergoing transarterial radioembolization (TARE).

MATERIALS AND METHODS

Forty-seven patients (27 men; mean age, 64 years) with NELMs who received TARE, along with pre-procedure liver MRI and 68Ga-DOTATATE positron emission tomography/computed tomography were included. Apparent diffusion coefficient and standardized uptake value (SUV) of three liver metastases, normal spleen and liver were measured. SUVmax or SUVmean were used for the calculation of tumor-to-organ ratios (tumor-to-spleen and tumor-to-liver ratios) using all possible combinations (including SUVmax/SUVmax, SUVmax/SUVmean, and SUVmean/SUVmean). Clinical parameters (hepatic tumor-burden, presence of extra-hepatic metastases, chromograninA, Ki-67 and bilirubin levels) were assessed. Overall survival, progression-free survival (PFS) and hepatic progression-free survival (HPFS) were calculated using Kaplan-Meier curves.

RESULTS

Median overall survival, PFS and HPFS were 49.6, 13.1 and 28.3 months, respectively. In multivariable Cox regression analysis, low Ki-67 (≤ 5%), low hepatic tumor-burden (< 10%), absence of extrahepatic metastases, and increased Tmean/Lmax ratio were significant prognostic factors of longer overall survival and HPFS. High baseline chromograninA (> 1330 ng/mL) was associated with shorter HPFS. Tmean/Lmax > 1.9 yielded a median overall survival of 69 vs. 33 months (P < 0.04), and a median HPFS of 30 vs. 19 months (P = 0.09). For PFS, high baseline SUVmax of NELMs was the single significant parameter in the multivariable model. SUVmax > 28 resulted in a median PFS of 16.9 vs. 6.5 months, respectively (P = 0.001).

CONCLUSION

High preinterventional Tmean/Lmax ratios, and high SUVmax on 68Ga-DOTATATE positron emission tomography/computed tomography seem to have prognostic value in patients with NELMs undergoing TARE, potentially aiding patient selection and management alongside conventional variables.

Diagnostic Management of Gastroenteropancreatic Neuroendocrine Neoplasms: Technique Optimization and Tips and Tricks for Radiologists

Gastroenteropancreatic neuroendocrine neoplasms (GEP-NENs) comprise a heterogeneous group of neoplasms, which derive from cells of the diffuse neuroendocrine system that specializes in producing hormones and neuropeptides and arise in most cases sporadically and, to a lesser extent, in the context of complex genetic syndromes. Furthermore, they are primarily nonfunctioning, while, in the case of insulinomas, gastrinomas, glucagonomas, vipomas, and somatostatinomas, they produce hormones responsible for clinical syndromes. The GEP-NEN tumor grade and cell differentiation may result in different clinical behaviors and prognoses, with grade one (G1) and grade two (G2) neuroendocrine tumors showing a more favorable outcome than grade three (G3) NET and neuroendocrine carcinoma. Two critical issues should be considered in the NEN diagnostic workup: first, the need to identify the presence of the tumor, and, second, to define the primary site and evaluate regional and distant metastases. Indeed, the primary site, stage, grade, and function are prognostic factors that the radiologist should evaluate to guide prognosis and management. The correct diagnostic management of the patient includes a combination of morphological and functional evaluations. Concerning morphological evaluations, according to the consensus guidelines of the European Neuroendocrine Tumor Society (ENETS), computed tomography (CT) with a contrast medium is recommended. Contrast-enhanced magnetic resonance imaging (MRI), including diffusion-weighted imaging (DWI), is usually indicated for use to evaluate the liver, pancreas, brain, and bones. Ultrasonography (US) is often helpful in the initial diagnosis of liver metastases, and contrast-enhanced ultrasound (CEUS) can solve problems in characterizing the liver, as this tool can guide the biopsy of liver lesions. In addition, intraoperative ultrasound is an effective tool during surgical procedures. Positron emission tomography (PET-CT) with FDG for nonfunctioning lesions and somatostatin analogs for functional lesions are very useful for identifying and evaluating metabolic receptors. The detection of heterogeneity in somatostatin receptor (SSTR) expression is also crucial for treatment decision making. In this narrative review, we have described the role of morphological and functional imaging tools in the assessment of GEP-NENs according to current major guidelines.

A descriptive analysis of the characteristics, treatment response and prognosis of hepatic dominant solid tumors undergoing selective internal radiation therapy (SIRT)

Background

Selective internal radiotherapy is widely used for liver dominant diseases of solid tumors. However, data about sequential treatment and prognostic factors are lacking.

Methods

We consecutively included all 209 patients who received a selective internal radiotherapy intervention between January 2015 and May 2019. A retrospective analysis of their electronic patient records was performed regarding diagnosis of cancer, previous therapies and applied radioactive activity. A multicenter follow-up at least 6 weeks after intervention to assess radiological response and irregular subsequent follow-ups to asses disease progression were conducted. In addition, subgroup analyses were carried out.

Results

The most frequently treated indications were hepatocellular carcinoma (37%), colorectal cancers (14%), neuroendocrine tumors (9%), and breast cancer (8%). In hepatocellular carcinoma, selective internal radiotherapy was most performed without prior systemic therapy (40%), and for the remaining indications, most often after surgery with systemic therapy in sequence. Local radiological response, defined as either regression or stable disease, was assessed at least 6 weeks after intervention and showed 52% across all indications. Hepatocellular carcinoma (59%) and breast cancer (67%) showed an excellent, colorectal cancers (29%) a particularly poor response rate. Neuroendocrine tumors showed the third longest median post-selective internal radiation therapy (SIRT) survival with 12.4 months and the second longest median progression-free time with 5.2 months. Hepatocellular carcinoma showed even better results with a post-SIRT survival of 15.7 months and a median progression-free time of 5.3 months. Pancreatic neuroendocrine tumors showed significantly worse outcomes than other neuroendocrine tumors, regarding median post-SIRT survival and median progression-free time. No relevant SIRT related differences among sexes were detected.

Conclusions

Patients with neuroendocrine tumors, breast cancer in late therapy lines and early-stage hepatocellular carcinoma seem to show better responses to SIRT than other entities. Colorectal cancers were mainly treated with SIRT in a second or third therapy line but with considerably weaker results than other entities.

The Evolving Role of Radioembolization in the Treatment of Neuroendocrine Liver Metastases

At diagnosis, 21-50% of neuroendocrine tumors already have distant metastases, of which the liver is most commonly affected. Unfortunately, the presence of neuroendocrine liver metastases (NELM) is the most incriminating factor for survival. At NELM diagnosis, 60-70% of patients suffer from bilobar multifocal disease, making them ineligible for surgical resection. With limited systemic options, a clinical need for liver-directed treatments exists. Trans-arterial (bland) embolization, chemoembolization and radioembolization have been increasingly used in the treatment of NELM. In recent years, radioembolization (also known as selective internal radiation therapy) has gained attention due to promising tumor reductive results, limited toxicities and increasing scientific evidence. This review provides basic insights into radioembolization as a technique, a summary of available literature on radioembolization in NELM, and discusses caveats, challenges and new insights when considering radioembolization in NELM.

Metastatic disease to the liver: Locoregional therapy strategies and outcomes

Secondary cancers of the liver are more than twenty times more common than primary tumors and are incurable in most cases. While surgical resection and systemic chemotherapy are often the first-line therapy for metastatic liver disease, a majority of patients present with bilobar disease not amenable to curative local resection. Furthermore, by the time metastasis to the liver has developed, many tumors demonstrate a degree of resistance to systemic chemotherapy. Fortunately, catheter-directed and percutaneous locoregional approaches have evolved as major treatment modalities for unresectable metastatic disease. These novel techniques can be used for diverse applications ranging from curative intent for small localized tumors, downstaging of large tumors for resection, or locoregional control and palliation of advanced disease. Their use has been associated with increased tumor response, increased disease-free and overall survival, and decreased morbidity and mortality in a broad range of metastatic disease. This review explores recent advances in liver-directed therapies for metastatic liver disease from primary colorectal, neuroendocrine, breast, and lung cancer, as well as uveal melanoma, cholangiocarcinoma, and sarcoma. Therapies discussed include bland transarterial embolization, chemoembolization, radioembolization, and ablative therapies, with a focus on current treatment approaches, outcomes of locoregional therapy, and future directions in each type of metastatic disease.

Liver-Directed Therapies for Neuroendocrine Neoplasms

PURPOSE OF REVIEW

To comprehensively synthesise and appraise the available evidence regarding therapies for metastatic neuroendocrine neoplasms that exploit the hepatic vasculature to deliver therapy to liver metastases.

RECENT FINDINGS

Various techniques including transarterial embolisation/chemoembolisation (TAE/TACE) and selective internal radiotherapy (SIRT, also termed radioembolisation [RE]) have been examined in patents with neuroendocrine liver metastases. Variations in the radioactive agents for selective internal radiotherapy (SIRT) have been explored, such as the use of Holmium-166, in addition to more established agents such as Yttrium-90. Recent trials have examined the safety and efficacy of combining liver-targeted therapy with systemic treatments, such as peptide receptor radionuclide therapy. More retrospective case series of liver-directed modalities will not provide additional knowledge. Randomised clinical trials have begun to compare the efficacy of different forms of liver-directed therapies, and also their combination with systemic treatment. Their results are expected to guide optimal treatment sequencing within multimodal concepts.

Liver Embolisation for Patients with Neuroendocrine Neoplasms: Systematic Review

BACKGROUND

Liver embolisation is one of the treatment options available for patients diagnosed with neuro-endocrine neoplasms (NEN). It is still uncertain whether the benefits of the various types of embolisation treatments truly outweigh the complications in NENs. This systematic review assesses the available data relating to liver embolisation in patients with NENs.

METHODS

Eligible studies (identified using MEDLINE-PubMed) were those reporting data on NEN patients who had undergone any type of liver embolisation. The primary end points were best radiological response and symptomatic response; secondary end-points included progression-free survival (PFS), overall survival (OS) and toxicity.

RESULTS

Of 598 studies screened, 101 were eligible: 16 were prospective (15.8%). The eligible studies included a total of 5,545 NEN patients, with a median of 39 patients per study (range 5-214). Pooled rate of partial response was 36.6% (38.9% achieved stable disease) and 55.2% of patients had a symptomatic response to therapy when pooled data were analysed. The median PFS and OS were 18.4 months (95% CI 15.5-21.2) and 40.7 months (95% CI 35.2-46.2) respectively. The most common toxicities were found to be abdominal pain (48.8%) and nausea (48.1%). Outcome did not significantly vary depending on the type of embolisation performed.

CONCLUSION

Liver embolisation provides adequate symptom relief for patients with carcinoid syndrome and is also able to reach partial response in a significant proportion of patients and a reasonable PFS. Quality of studies was limited, highlighting the need of further prospective studies to confirm the most suitable form of liver embolisation in NENs.

Association between objective response rate and overall survival in metastatic neuroendocrine tumors treated with radioembolization: a systematic literature review and regression analysis

OBJECTIVES

Neuroendocrine tumors (NETs) are a heterogeneous group of cancers arising from neuroendocrine cells. The aim was to evaluate objective response rate (ORR) as a predictor of overall survival (OS) in patients with metastatic NETs (mNETs) treated with radioembolization (RE).

METHODS

Randomized controlled trials and observational studies of RE treatment of mNETs were identified by systematic literature review (SLR). Pooled ORR and OS estimates were calculated and a weighted generalized linear model (GLM) of ORR as a predictor of OS was derived, stratified by ORR assessment criteria and RE type (Yttrium-90 resin or glass microspheres).

RESULTS

The SLR identified 32 observational studies. Mean ORR was 41% (95% confidence interval 38-45%). The Yttrium-90 resin and glass microsphere GLMs accounted for 59% and 57% of OS deviance, respectively. ORR was a significant predictor of OS in the resin microspheres model (p < 0.001), but not the glass microspheres model (p = 0.11).

CONCLUSIONS

A weighted GLM showed a significant relationship between ORR and OS in patients with mNETs treated with Yttrium-90 resin microspheres. ORR could therefore potentially be an OS surrogate in future trials of Yttrium-90 resin microspheres. Further research is needed to confirm the relationship between ORR and OS and the difference between resin and glass microspheres.

Verification Study of Residual Activity Measurements After Yttrium-90 Radioembolization with Glass Microspheres

Objective

After yttrium-90 (90Y) radioembolization, residual activity and its consequences for dosimetric calculations are often not reported. The manufacturer for glass microspheres prescribes standard residual activity measurements by a survey meter, but the validity lacks evidence. This study aims to verify the accuracy of the survey meter approach for measuring residual activity of glass microspheres after treatment with glass microspheres.

Methods

To validate the accuracy of the survey meter approach, the measured residual activity of glass microspheres by survey meter was compared with measurements by PET. A sample of these waste containers was also measured by dose calibrator to confirm the accuracy of the PET.

Results

Twenty-four waste containers from glass microsphere treatments were prospectively scanned with 90Y-PET/CT. Bland–Altman plots showed substantial disagreement in residual activity measured by survey meter versus the residual activity measured by PET and dose calibrator, whereas the correlation between PET and dose calibrator was excellent (ρ = 0.99).

Conclusion

This study found a significant disagreement between the residual activities measured by the survey meter, compared to measurements by PET and dose calibrator. If relatively high amounts of residual activity are encountered using the exposure rate measurement with a survey meter, additional quantification should be considered using either PET/CT or a dose calibrator measurement.

The Role of Interventional Radiology for the Treatment of Hepatic Metastases from Neuroendocrine Tumor: An Updated Review

Interventional radiology plays an important role in the management of patients with neuroendocrine tumor liver metastasis (NELM). Transarterial embolization (TAE), transarterial chemoembolization (TACE), and selective internal radiation therapy (SIRT) are intra-arterial therapies available for these patients in order to improve symptoms and overall survival. These treatment options are proposed in patients with NELM not responding to systemic therapies and without extrahepatic progression. Currently, available data suggest that TAE should be preferred to TACE in patients with NELM from extrapancreatic origin because of similar efficacy and better patient tolerance. TACE is more effective in patients with pancreatic NELM and SIRT has shown promising results along with good tolerance. However, large randomized controlled trials are still lacking in this setting. Available literature mainly consists in small sample size and retrospective studies with important technical heterogeneity. The purpose of this review is to provide an updated overview of the currently reported endovascular interventional radiology procedures that are used for the treatment of NELM.

Expected and Unexpected Imaging Findings after 90Y Transarterial Radioembolization for Liver Tumors

Transarterial radioembolization (TARE), also called radioembolization or selective internal radiation therapy, is an interventional radiology technique used to treat primary liver tumors and liver metastases. The aim of this therapy is to deliver tumoricidal doses of radiation to liver tumors while selecting a safe radiation dose limit for nontumoral liver and lung tissue. Hence, correct treatment planning is essential to obtaining good results. However, this treatment invariably results in some degree of irradiation of normal liver parenchyma, inducing different radiologic findings that may affect follow-up image interpretation. When evaluating treatment response, the treated area size, tumor necrosis, devascularization, and changes seen at functional MRI must be taken into account. Unlike with other interventional procedures, with TARE, it can take several months for the tumor response to become evident. Ideally, responding lesions will show reduced size and decreased enhancement 3-6 months after treatment. In addition, during follow-up, there are many imaging findings related to the procedure itself (eg, peritumoral edema, inflammation, ring enhancement, hepatic fibrosis, and capsular retraction) that can make image interpretation and response evaluation difficult. Possible complications, either hepatic or extrahepatic, also can occur and include biliary injuries, hepatic abscess, radioembolization-induced liver disease, and radiation pneumonitis or dermatitis. A complete understanding of these possible posttreatment changes is essential for correct radiologic interpretations during the follow-up of patients who have undergone TARE. ^©RSNA, 2019.

Non-Pharmacological Therapeutic Options for Liver Metastases in Advanced Neuroendocrine Tumors

The incidence of liver metastasis in digestive neuroendocrine tumors is high. Their presence appears as an important prognostic factor in terms of quality of life and survival. These tumors may be symptomatic because of the tumor burden itself and/or the hormonal hyper-secretion induced by the tumor. Surgery is the treatment of choice for resectable tumors and metastasis. Nevertheless, surgery is only possible in a small number of cases. The management of non-resectable liver metastasis is a challenge. The literature is rich but consists predominantly in small retrospective series with a low level of proof. Thus, the choice of one technique over another could be difficult. Local ablative techniques (radiofrequency) or trans-catheter intra-arterial liver-directed treatments (hepatic artery embolization, chemo-embolization, and radio-embolization) are frequently considered for liver metastasis. In the present review, we focus on these different therapeutic approaches in advanced neuroendocrine tumors, results (clinical and radiological), and overall efficacy, and summarize recommendations to help physicians in their clinical practice.

Radioembolisation with 90Y microspheres for neuroendocrine liver metastases: an institutional case series, systematic review and meta-analysis

BACKGROUND

Neuroendocrine liver metastases are clinically challenging due to their frequent disseminated distribution. This study aims to present a British experience with an emerging modality, radioembolisation with yttrium-90 labelled microspheres, and embed this within a meta-analysis of response and survival outcomes.

METHODS

A retrospective case series of patients treated with SIR-Spheres (radiolabelled resin microspheres) was performed. Results were included in a systematic review and meta-analysis of published results with glass or resin microspheres. Objective response rate (ORR) was defined as complete or partial response. Disease control rate (DCR) was defined as complete/partial response or stable disease.

RESULTS

Twenty-four patients were identified. ORR and DCR in the institutional series was 14/24 and 21/24 at 3 months. Overall survival and progression-free survival at 3-years was 77.6% and 50.4%, respectively. There were no grade 3/4 toxicities post-procedure. A fixed-effects pooled estimate of ORR of 51% (95% CI: 47%-54%) was identified from meta-analysis of 27 studies. The fixed-effects weighted average DCR was 88% (95% CI: 85%-90%, 27 studies).

CONCLUSION

Current data demonstrate evidence of the clinical effectiveness and safety of radioembolisation for neuroendocrine liver metastases. Prospective randomised studies to compare radioembolisation with other liver directed treatment modalities are needed.

Radioembolization of Hepatocellular Carcinoma with Built-In Dosimetry: First in vivo Results with Uniformly-Sized, Biodegradable Microspheres Labeled with 188Re

A common form of treatment for patients with hepatocellular carcinoma (HCC) is transarterial radioembolization (TARE) with non-degradable glass or resin microspheres (MS) labeled with ⁹⁰Y (⁹⁰Y-MS). To further simplify the dosimetry calculations in the clinical setting, to have more control over the particle size and to change the permanent embolization to a temporary one, we developed uniformly-sized, biodegradable ¹⁸⁸Re-labeled MS (¹⁸⁸Re-MS) as a new and easily imageable TARE agent.

Methods: MS made of poly(L-lactic acid) were produced in a flow focusing microchip. The MS were labeled with ¹⁸⁸Re using a customized kit. An orthotopic HCC animal model was developed in male Sprague Dawley rats by injecting N1-S1 cells directly into the liver using ultrasound guidance. A suspension of ¹⁸⁸Re-MS was administered via hepatic intra-arterial catheterization 2 weeks post-inoculation of the N1-S1 cells. The rats were imaged by SPECT 1, 24, 48, and 72 h post-radioembolization.

Results: The spherical ¹⁸⁸Re-MS had a diameter of 41.8 ± 6.0 µm (CV = 14.5%). The site and the depth of the injection of N1-S1 cells were controlled by visualization of the liver in sonograms. Single 0.5 g tumors were grown in all rats. ¹⁸⁸Re-MS accumulated in the liver with no deposition in the lungs. ¹⁸⁸Re decays to stable ¹⁸⁸Os by emission of β^¯ particles with similar energy to those emitted by ⁹⁰Y while simultaneously emitting γ photons, which were imaged directly by single photon computed tomography (SPECT). Using Monte Carlo methods, the dose to the tumors was calculated to be 3-6 times larger than to the healthy liver tissue.

Conclusions:¹⁸⁸Re-MS have the potential to become the next generation of β^¯-emitting MS for TARE. Future work revolves around the investigation of the therapeutic potential of ¹⁸⁸Re-MS in a large-scale, long-term preclinical study as well as the evaluation of the clinical outcomes of using ¹⁸⁸Re-MS with different sizes, from 20 to 50 µm.

Radioembolization Versus Bland Embolization for Hepatic Metastases from Small Intestinal Neuroendocrine Tumors: Short-Term Results of a Randomized Clinical Trial

Background

Radioembolization (RE) with intra-arterial administration of ⁹⁰Y microspheres is a promising technique for the treatment of liver metastases from small intestinal neuroendocrine tumors (SI-NET) not amenable to surgery or local ablation. However, studies comparing RE to other loco-regional therapies are lacking. The aim of this randomized study was to compare the therapeutic response and safety after RE and bland hepatic arterial embolization (HAE), and to investigate early therapy-induced changes with diffusion-weighted MRI (DWI-MRI).

Methods

Eleven patients were included in a prospective randomized controlled pilot study, six assigned to RE and five to HAE. Response according to RECIST 1.1 using MRI or CT at 3 and 6 months post-treatment was recorded as well as changes in DWI-MRI parameters after 1 month. Data on biochemical tumor response, toxicity, and side effects were also collected.

Results

Three months after treatment, all patients in the HAE group showed partial response according to RECIST while none in the RE group did (p = 0.0022). After 6 months, the response rates were 4/5 (80%) and 2/6 (33%) in the HAE and RE groups, respectively (NS). DWI-MRI metrics could not predict RECIST response, but lower pretreatment ADC_(120–800) and larger ADC_(0–800) increase at 1 month were related to larger decrease in tumor diameter when all tumors were counted.

Conclusion

HAE resulted in significantly higher RECIST response after 3 months, but no difference compared to RE remained after 6 months. These preliminary findings indicate that HAE remains a safe option for the treatment of liver metastases from SI-NET, and further studies are needed to establish the role of RE and the predictive value of MR-DWI.

Electronic supplementary material

The online version of this article (10.1007/s00268-017-4324-9) contains supplementary material, which is available to authorized users.

Biodistribution, Pharmacokinetics and Efficacy of 188Re(I)-Tricarbonyl-Labeled Human Serum Albumin Microspheres in an Orthotopic Hepatoma Rat Model

BACKGROUND/AIM

The biodistribution, pharmacokinetics and therapeutic evaluation of ¹⁸⁸Re-human serum albumin microspheres (¹⁸⁸Re-HSAM) by labeling with ¹⁸⁸Re(I)-tricarbonyl ion (¹⁸⁸Re(OH₂)₃(CO)₃)+) were investigated in a GP7TB orthotopic hepatoma rat model.

MATERIALS AND METHODS

Male F344 rats received intrahepatic inoculations with GP7TB 1 mm3 cubes. The efficacy of ¹⁸⁸Re-HSAM was examined following a single-dose treatment via the intraarterial route. Rats were monitored for survival until death.

RESULTS

The labeling efficiency of the ¹⁸⁸Re-HSAM was about 80%. After intraarterial administration of ¹⁸⁸Re-HSAM, radioactivity in tumors accumulated from 18.41±3.48 %ID/g at 1 h to 12.43±4.70 %ID/g at 24 h. The tumor/liver ratios ranged from 3.03 at 1 h to 1.89 at 72 h. The major uptake organs of ¹⁸⁸Re-HSAM were liver (73.35%ID to 48.92%ID), tumor (10.54%ID to 3.51%ID) and kidney (7.48 %ID to 0.14%ID). The T_1/2λz of ¹⁸⁸Re-HSAM was 259.34 h after intraarterial injection. The AUC_{(0→96 h)} of ¹⁸⁸Re-HSAM was 0.69 h*% ID/g. In the efficacy study, the median survival time for the rat (n=6), that received normal saline was 80 d. The median survival times for the mice treated with 10 mCi (n=4), 5.2 mCi (n=6) and 2.9 mCi (n=3) of ¹⁸⁸Re-HSAM were 130 d (p=0.003), 106 d (p=0.002) and 83.5 d (p=0.617), respectively. The increase in life span of 10 mCi, 5.2 mCi and 2.9 mCi of ¹⁸⁸Re-HSAM were 62.5%, 32.5% and 4.4%, respectively.

CONCLUSION

Administration of ¹⁸⁸Re-HSAM demonstrated better survival time and therapeutic efficacy at the higher dose in the GP7TB hepatoma model. These results suggested that intraarterial administration of ¹⁸⁸Re-HSAM could provide a benefit and promising strategy for delivery of radiotherapeutics in oncology applications.

Biodistribution, Pharmacokinetics and Efficacy of 188Re(I)-Tricarbonyl-Labeled Human Serum Albumin Microspheres in an Orthotopic Hepatoma Rat Model

BACKGROUND/AIM

The biodistribution, pharmacokinetics and therapeutic evaluation of ¹⁸⁸Re-human serum albumin microspheres (¹⁸⁸Re-HSAM) by labeling with ¹⁸⁸Re(I)-tricarbonyl ion (¹⁸⁸Re(OH₂)₃(CO)₃)+) were investigated in a GP7TB orthotopic hepatoma rat model.

MATERIALS AND METHODS

Male F344 rats received intrahepatic inoculations with GP7TB 1 mm3 cubes. The efficacy of ¹⁸⁸Re-HSAM was examined following a single-dose treatment via the intraarterial route. Rats were monitored for survival until death.

RESULTS

The labeling efficiency of the ¹⁸⁸Re-HSAM was about 80%. After intraarterial administration of ¹⁸⁸Re-HSAM, radioactivity in tumors accumulated from 18.41±3.48 %ID/g at 1 h to 12.43±4.70 %ID/g at 24 h. The tumor/liver ratios ranged from 3.03 at 1 h to 1.89 at 72 h. The major uptake organs of ¹⁸⁸Re-HSAM were liver (73.35%ID to 48.92%ID), tumor (10.54%ID to 3.51%ID) and kidney (7.48 %ID to 0.14%ID). The T_1/2λz of ¹⁸⁸Re-HSAM was 259.34 h after intraarterial injection. The AUC_{(0→96 h)} of ¹⁸⁸Re-HSAM was 0.69 h*% ID/g. In the efficacy study, the median survival time for the rat (n=6), that received normal saline was 80 d. The median survival times for the mice treated with 10 mCi (n=4), 5.2 mCi (n=6) and 2.9 mCi (n=3) of ¹⁸⁸Re-HSAM were 130 d (p=0.003), 106 d (p=0.002) and 83.5 d (p=0.617), respectively. The increase in life span of 10 mCi, 5.2 mCi and 2.9 mCi of ¹⁸⁸Re-HSAM were 62.5%, 32.5% and 4.4%, respectively.

CONCLUSION

Administration of ¹⁸⁸Re-HSAM demonstrated better survival time and therapeutic efficacy at the higher dose in the GP7TB hepatoma model. These results suggested that intraarterial administration of ¹⁸⁸Re-HSAM could provide a benefit and promising strategy for delivery of radiotherapeutics in oncology applications.

Yttrium-90 radioembolization for unresectable metastatic neuroendocrine liver tumor: A systematic review

OBJECTIVE

To evaluate the value of yttrium-90 (⁹⁰Y) microspheres in the management of unresectable liver metastases secondary to neuroendocrine tumors (NETs).

MATERIALS AND METHODS

PubMed, EMBASE, the Cochrane Database of Systematic Reviews, and the "gray" literature (Google Scholar) were searched for all studies related to ⁹⁰Y therapy for unresectable liver metastases of NETs.

RESULTS

A total of 11 studies and 7 abstracts involving 870 patients were included in the final analysis. In 11 of these studies, 19.8% (77/388) of patients had undergone transarterial bland embolization (TABE) or transarterial chemoembolization (TACE) before ⁹⁰Y therapy. The median disease control rate among all patients was 86% at 3 months after ⁹⁰Y therapy. The median survival was 28 months, with 1-, 2-, and 3-year survival rates of 72.5%, 57%, and 45%, respectively. The median survival values for patients who received resin- and glass-based ⁹⁰Y treatment were 27.6 and 31.7 months, respectively. The survival values for patients with carcinoid, pancreatic, and unclassified origin of NETs were 56, 31, and 28 months, respectively; the survival values for patients with grade I, II, and III NETs were 71, 56, and 28 months, respectively. Carcinoid syndrome was reported in 52.4% (55/105) of patients, and 69.1% of those with clinical symptoms demonstrated improvement in symptoms after ⁹⁰Y radioembolization. Complications were reported in 9 studies, including radiation gastritis (n = 4), duodenal ulcer (n = 2), death due to liver failure (n = 1), and radiation cholecystitis (n = 1). The most common side effects were abdominal pain (median, 32.6%), nausea/vomiting (median, 32.5%), and fatigue (median, 30.4%).

CONCLUSIONS

⁹⁰Y radioembolization can be used as an alternative therapy for unresectable liver metastases of NETs, with an improved survival rate and tumor response. This treatment is also effective for patients who have undergone unsuccessful TABE/TACE therapy and for the relief of symptoms in patients with carcinoid syndrome.

Liver transarterial embolizations in metastatic neuroendocrine tumors

The management of patients with well-differentiated neuroendocrine tumors (NET) and non-resectable liver metastases is challenging. Liver-directed transarterial embolization (TAE), transarterial chemo-embolization (TACE) and selective internal radiation therapy (SIRT) have a place of choice among other treatment modalities. However, their utilization relies on a low level of proof, due to the lack of prospective data, the absence of comparative studies and considerable heterogeneity between local practices. TAE and TACE generally achieve average symptomatic, biological and radiological responses of 75%, 56% and 50%, with progression-free survival of 12-18 months, with acceptable tolerance. Although not clearly demonstrated, TACE may be more effective than TAE in pancreatic NET, but not in small-intestine NET. SIRT has been developed more recently and may achieve similar results, with improved tolerance, but decreased cost-effectiveness, although no prospective comparison has been published to date. There is currently no strong argument to choose between TAE, TACE and SIRT, and they have not been compared to other treatment modalities. The evaluation of their efficacy has mostly relied on criteria based on size variations, which do not take into account tumor viability and metabolism, and thus may not be relevant. These techniques may be especially effective when performed as first-line therapies, in patients with non-major liver involvement (<75%) and with hypervascular metastases. Finally, studies exploring their combination with systemic therapies are ongoing.

Single-institution experience of radioembolization with yttrium-90 microspheres for unresectable metastatic neuroendocrine liver tumors

BACKGROUND AND AIM

The aim of this study was to assess the effectiveness of yttrium-90 (⁹⁰ Y) microspheres for the treatment of unresectable metastatic liver neuroendocrine tumors (NET).

METHODS

From February 2006 to September 2015, 36 patients (19 male and 17 female, age 63.6 ± 9.4 years) who underwent ⁹⁰ Y therapy for unresectable liver metastases of NET were included and analyzed retrospectively. All patients received a variety of treatments before ⁹⁰ Y therapy. The radiological response, symptoms improvement of carcinoid syndrome, tumor marker changes, complications, side effects/toxicity, survival, and factors related to survival were evaluated and analyzed.

RESULTS

Of the 36 patients, the mean delivered dose of ⁹⁰ Y was 1.8 ± 0.7 GBq with a total of 40 treatments. Overall disease control rate was 88.9% (32/36) at 3 months following therapy. In 16 patients with carcinoid syndrome, 15 (93.8%) patients had symptomatic improvement. Tumor marker response (5-hydroxyindoleacetic acid [n = 7] and chromogranin A [n = 13]) at 3 months after treatment were as follows: none (n = 0, 4), partial (n = 6, 7), and complete (n = 1, 2). Radiation-induced gastrointestinal ulcers (n = 2, 5.6%) were identified. Side effects included fatigue (n = 31, 86.1%), anorexia (n = 26, 72.2%), nausea (n = 15, 41.7%), vomiting (n = 14, 38.9%), abdominal pain (n = 10, 27.8%), and fever (n = 8, 22.2%). The mean follow-up was 27.0 ± 16.4 months, with a median survival of 41.0 months. Child-Pugh classification (P = 0.008) and lymph node metastases (P = 0.045) had statistically significant influence on overall survival.

CONCLUSIONS

Yttrium-90 radioembolization can be effective in the treatment of unresectable liver metastases of NET who failed to respond to other treatments.

Imaging, biodistribution and efficacy evaluation of 188Re-human serum albumin microspheres via intraarterial route in an orthotopic hepatoma model

PURPOSE

Liver cancer is the second most common cause of death worldwide. This study was to investigate the SPECT/CT, ultrasound, biodistribution and therapeutic evaluation of ¹⁸⁸Re-human serum albumin microspheres (¹⁸⁸Re-HSAM) in the GP7TB orthotopic hepatoma rat model.

MATERIALS AND METHODS

HSAM was labeled with ¹⁸⁸Re by using a home-made kit and microwave system. The ¹⁸⁸Re-HSAM was administered via intraarterial route. The in vivo distribution of ¹⁸⁸Re-HSAM was determined by biodistribution analysis and nanoSPECT/CT system. In efficacy, tumor volumes were tracked longitudinally by three-dimensional ultrasound.

RESULTS

The biodistribution and nanoSPECT/CT imaging showed that ¹⁸⁸Re-HSAM could accumulate in liver and tumor. The correlation coefficient of tumor volumes done by three-dimensional ultrasound and at autopsy was 0.997. In efficacy, tumor volume in the normal saline-treated group was 1803.2 mm³ at 54 days after tumor inoculation. Tumor volumes in the 103.6 MBq and 240.5 MBq of ¹⁸⁸Re-HSAM treated groups were 381 and 267.4 mm³ (p = 0.001 and 0.004), respectively.

CONCLUSIONS

These results show that three-dimensional ultrasound with a high spatial resolution and contrast in soft tissue can become imaging modality in assessing tumor burden and tumor progression in an orthotopic rat model. The longitudinally therapeutic evaluation of ¹⁸⁸Re-HSAM demonstrated dose-dependent tumor growth inhibition with increased dose in the GP7TB orthotopic hepatoma rat model.

Neuroendocrine tumor liver metastases treated with yttrium-90 radioembolization

OBJECTIVE

Yttrium-90 (Y-90) radioembolization is an emerging treatment option for unresectable neuroendocrine liver metastases (NELM). However, the data regarding this treatment are currently limited. This study evaluates the efficacy and tolerability of Y-90 radioembolization and identifies prognostic factors for radiographic response and survival.

METHODS AND MATERIALS

Thirty-eight patients underwent Y-90 radioembolization for NELM at our institution between April 2004 and February 2012. Patients were assessed radiographically (RECIST criteria, enhancement), serologically, and clinically at 1month, and then at every 3months after treatment for tumor response, toxicity, and survival outcomes.

RESULTS

Median length of follow-up was 17.0months (IQR, 9.0-37.0). Median survival was 29.2months. Three patients (9%) had a radiographic complete response to treatment, 6 (17%) had a partial response, 21 (60%) had stable disease, and 5 (14%) developed progressive disease. Two factors were significantly associated with a good radiographic response (complete/partial response): islet cell histological subtype (p=0.043) and hepatic tumor burden ≥33% (p=0.031). Multivariate analysis revealed that patients requiring multiple Y-90 treatments (HR 2.9, p=0.035) and patients who had previously failed systemic therapy with octreotide/chemotherapy (HR 4.4, p=0.012) had worse survival. Grade 3 serologic toxicity was observed in 2 patients (5%; hyperbilirubinemia, elevated alkaline phosphatase) after treatment. Grade 3 non-serologic toxicities included abdominal pain (11%), fatigue (11%), nausea/vomiting (5%), ascites (5%), dyspnea (3%), diarrhea (3%), and peripheral edema (3%). No grade 4 or 5 toxicity was reported.

CONCLUSIONS

Y-90 radioembolization is a promising treatment option for inoperable NELM and is associated with low rates of grade≥3 toxicity.

Current status of transarterial radioembolization

Unresectable primary and secondary liver malignancies present a major problem in the treatment of solid tumors. Transarterial radioembolization (TARE) is an increasingly used technique for treating various types of malignant liver tumors. This approach is appealing, as the mechanism of action is independent from other loco-regional treatments and potentially complementary to systemic therapies. There are two commercially available products in use for TARE: ⁹⁰Y-resin and ⁹⁰Y-glass microspheres. Currently available data indicates TARE so be safe and effective in hepatocellular carcinoma (HCC) and metastatic liver disease. In HCC the results compare well with chemoembolization, while the role of TARE in combination with kinase inhibitors has yet to be established. Current data on TARE in metastatic liver disease is promising, but there is a strong need for prospective randomized trials comparing TARE and modern chemotherapeutic regimen to support the growing role of TARE in metastatic liver disease.

Arterial Therapies of Non-Colorectal Liver Metastases

BACKGROUND

The unique situation of the liver with arterial and venous blood supply and the dependency of the tumor on the arterial blood flow make this organ an ideal target for intrahepatic catheter-based therapies. Main forms of treatment are classical bland embolization (TAE) cutting the blood flow to the tumors, chemoembolization (TACE) inducing high chemotherapy concentration in tumors, and radioembolization (TARE) without embolizing effect but very high local radiation. These different forms of therapies are used in different centers with different protocols. This overview summarizes the different forms of treatment, their indications and protocols, possible side effects, and available data in patients with non-colorectal liver tumors.

METHODS

A research in PubMed was performed. Mainly clinical controlled trials were reviewed. The search terms were 'embolization liver', 'TAE', 'chemoembolization liver', 'TACE', 'radioembolization liver', and 'TARE' as well as 'chemosaturation' and 'TACP' in the indications 'breast cancer', 'neuroendocrine', and 'melanoma'. All reported studies were analyzed for impact and reported according to their clinical relevance.

RESULTS

The main search criteria revealed the following results: 'embolization liver + breast cancer', 122 results, subgroup clinical trials 16; 'chemoembolization liver + breast cancer', 62 results, subgroup clinical trials 11; 'radioembolization liver + breast cancer', 37 results, subgroup clinical trials 3; 'embolization liver + neuroendocrine', 283 results, subgroup clinical trials 20; 'chemoembolization liver + neuroendocrine', 202 results, subgroup clinical trials 9; 'radioembolization liver + neuroendocrine', 64 results, subgroup clinical trials 9; 'embolization liver + melanoma', 79 results, subgroup clinical trials 15; 'chemoembolization liver + melanoma', 60 results, subgroup clinical trials 14; 'radioembolization liver + melanoma', 18 results, subgroup clinical trials 3. The term 'chemosaturation liver' was tested without indication since only few publications exist and provided us with five results and only one clinical trial.

CONCLUSION

Despite many years of clinical use and documented efficacy on intra-arterial treatments of the liver, there are still only a few prospective multicenter trials with many different protocols. To guarantee the future use of these efficacious therapies, especially in the light of many systemic or surgical therapies in the treatment of non-colorectal liver metastases, further large randomized trials and transparent guidelines need to be established.

How Effective Are Percutaneous Liver-Directed Therapies in Patients with Non-Colorectal Liver Metastases?

BACKGROUND

The purpose of this review is to demonstrate the clinical indications, technical developments, and outcome of liver-directed therapies in interventional oncology of non-colorectal liver metastases.

METHODS

Liver-directed therapies are classified into vascular transarterial techniques such as chemoperfusion (TACP), chemoembolization (TACE), radioembolization (selective internal radiation therapy (SIRT)), and chemosaturation, as well as thermal ablation techniques like microwave ablation (MWA), radiofrequency ablation (RFA), laser-induced thermotherapy (LITT), cryotherapy, and irreversible electroporation (IRE). The authors searched the database PubMed using the following terms: 'image-guided tumor ablation', 'thermal ablation therapies', 'liver metastases of uveal melanoma', 'neuroendocrine carcinoma', 'breast cancer', and 'non-colorectal liver metastases'.

RESULTS

Various combinations of the above-mentioned therapy protocols are possible. In neuroendocrine carcinomas, oligonodular liver metastases are treated successfully via thermal ablation like RFA, LITT, or MWA, and diffuse involvement via TACE or SIRT. Although liver involvement in breast cancer is a systemic disease, non-responding nodular metastases can be controlled via RFA or LITT. In ocular or cutaneous melanoma, thermal ablation is rarely considered as an interventional treatment option, as opposed to TACE, SIRT, or chemosaturation. Rarely liver-directed therapies are used in pancreatic cancer, most likely due to problems such as biliary digestive communications after surgery and the risk of infections. Rare indications for thermal ablation are liver metastases of other primary cancers like non-small cell lung, gastric, and ovarian cancer.

CONCLUSION

Interventional oncological techniques play a role in patients with liver-dominant metastases.

Molecular response assessed by (68)Ga-DOTANOC and survival after (90)Y microsphere therapy in patients with liver metastases from neuroendocrine tumours

PURPOSE

We investigated the prognostic role of (68)Ga-DOTANOC in patients affected by hepatic metastases from neuroendocrine tumours (NET) undergoing (90)Y radioembolization ((90)Y-RE).

METHODS

A group of 15 consecutive patients with unresectable NET liver metastases underwent (68)Ga-DOTANOC PET at baseline and 6 weeks after (90)Y-RE. Molecular response was defined as a reduction of >50% in the tumour-to-spleen ratio (ΔT/S). The patients were divided into two groups (responders with ΔT/S >50% and nonresponders with ΔT/S <50%) Patients were followed up by imaging and laboratory tests every 3 months until death or for at least 36 months following (90)Y-RE. Statistical analysis was performed to identify factors predicting overall survival (OS) and progression-free survival (PFS).

RESULTS

A decrease in T/S ratio was seen in all patients on (68)Ga-DOTANOC PET scans performed after (90)Y-RE. Nine patients were classified as responders and six as nonresponders. The mean OS in all patients was 31.0 months. Responders had a significantly (p < 0.001) longer OS (mean 36.0 ± 2.5 months) and PFS (mean 29.7 ± 3.4 months) than nonresponders. In a multivariate analysis, none of the other examined variables including age, unilobar vs. bilobar locations, bilirubin levels, radiological response or the presence of extrahepatic disease significantly predicted patient outcome.

CONCLUSION

Molecular response assessed with (68)Ga-DOTANOC PET might be a useful predictor of survival in patients affected by NET liver metastases treated with (90)Y-RE.