Radioembolization with 90Y Resin Microspheres of Neuroendocrine Liver Metastases: International Multicenter Study on Efficacy and Toxicity

Dose-effect relationships in neuroendocrine tumour liver metastases treated with [166Ho]-radioembolization

PURPOSE

Aim of this study was to investigate a dose-response relationship, dose-toxicity relationship, progression free survival (PFS) and overall survival (OS) in neuroendocrine tumour liver metastases (NELM) treated with holmium-166-microspheres radioembolization ([166Ho]-radioembolization).

MATERIALS AND METHODS

Single center, retrospective study included patients with NELM that received [166Ho]-radioembolization with post-treatment SPECT/CT and CECT or MRI imaging for 3 months follow-up. Post-treatment SPECT/CT was used to calculate tumour (Dt) and whole liver healthy tissue (Dh) absorbed dose. Clinical and laboratory toxicity was graded by Common Terminology Criteria for Adverse Events (CTCAE), version 5 at baseline and three-months follow-up. Response was determined according to RECIST 1.1. The tumour and healthy doses was correlated to lesion-based objective response and patient-based toxicity. Kaplan Meier analyses were performed for progression free survival (PFS) and overall survival (OS).

RESULTS

Twenty-seven treatments in 25 patients were included, with a total of 114 tumours. Median follow-up was 14 months (3 - 82 months). Mean Dt in non-responders was 68 Gy versus 118 Gy in responders, p = 0.01. ROC analysis determined 86 Gy to have the highest sensitivity and specificity, resp. 83% and 81%. Achieving a Dt of ≥ 120 Gy provided the highest likelihood of response (90%) for obtaining response. Sixteen patients had grade 1-2 clinical toxicity and only one patient grade 3. No clear healthy liver dose-toxicity relationship was found. The median PFS was 15 months (95% CI [10.2;19.8]) and median OS was not reached.

CONCLUSION

This study confirms the safety and efficacy of [166Ho]-radioembolization in NELM in a real-world setting. A clear dose-response relationship was demonstrated and future studies should aim at a Dt of ≥ 120 Gy, being predictive of response. No dose-toxicity relationship could be established.

Partition Dosimetry and Outcomes of Metastatic Neuroendocrine Tumors after Yttrium-90 Resin Microsphere Radioembolization

PURPOSE

To characterize estimated mean tumor-absorbed dose (ADT) and objective response of metastatic neuroendocrine tumor (NET) after resin microsphere yttrium-90 (90Y) hepatic radioembolization using partition dosimetry.

MATERIALS AND METHODS

In this retrospective, single-center study, multicompartment dosimetry of index tumors receiving 90Y radioembolization between 2013 and 2022 involved the use of Sureplan (MIM Software, Cleveland, Ohio) and technetium-99m macroaggregated albumin single photon emission computed tomography (SPECT) combined with computed tomography. Thirty-six patients with NET underwent treatment of 56 index tumors. Patients underwent imaging every 3-6 months after treatment to determine best response per Response Evaluation Criteria in Solid Tumors (RECIST) 1.1 and modified RECIST (mRECIST) criteria. Responses were categorized as objective response (OR) or nonresponse (NR). Wilcoxon rank sum test evaluated differences in continuous variables, and Pearson χ2 test evaluated differences in categorical variables.

RESULTS

Median follow-up was 582 days (IQR, 187-1,227 days). Per RECIST 1.1, 27 patients (75%) experienced OR and 9 patients experienced (25%) NR. Of the 36 patients, 33 (92%) showed hypervascular, mRECIST-evaluable tumors. Among them, 28 patients (85%) showed mRECIST OR and 5 patients (15%) showed NR. The mRECIST OR group received a higher ADT than the NR group (median, 107 Gy; IQR, 95.1-154 Gy vs median, 70.4 Gy; IQR, 62.9-87.6 Gy; P = .048). All tumors receiving at least 120 Gy showed mRECIST OR.

CONCLUSIONS

In hypervascular metastatic NET treated by 90Y resin microsphere radioembolization, higher tumor dose was associated with better tumor response per mRECIST. Doses of ≥120 Gy led to OR.

SEOM-GETNE clinical guidelines for the diagnosis and treatment of gastroenteropancreatic and bronchial neuroendocrine neoplasms (NENs) (2022)

Neuroendocrine neoplasms (NENs) are a heterogeneous family of tumors of challenging diagnosis and clinical management. Their incidence and prevalence continue to rise mainly due to an improvement on diagnostic techniques and awareness. Earlier detection, along with steadfast improvements in therapy, has led to better prognosis over time for advanced gastrointestinal and pancreatic neuroendocrine tumors. The aim of this guideline is to update evidence-based recommendations for the diagnosis and treatment of gastroenteropancreatic and lung NENs. Diagnostic procedures, histological classification, and therapeutic options, including surgery, liver-directed therapy, peptide receptor radionuclide therapy, and systemic hormonal, cytotoxic or targeted therapy, are reviewed and discussed, and treatment algorithms to guide therapeutic decisions are provided.

Conventional Transarterial Chemo embolization Using Streptozocin in Patients with Unresectable Neuroendocrine Liver Metastases

BACKGROUND

The purpose of this study was to evaluate the clinical, biological and radiological responses to, and tolerability of, conventional transarterial chemoembolization (cTACE) using streptozocin for unresectable neuroendocrine liver metastases.

PATIENTS AND METHODS

A total of 52 patients with predominant liver disease were treated with cTACE using an emulsion of streptozocin, Lipiodol and embolization particles. A sequential approach was favored in patients with high liver tumor burden. Clinical, biological and radiological responses were evaluated using carcinoid symptoms, biomarkers and mRecist criteria, respectively.

RESULTS

A total of 127 procedures were performed with a sequential approach in 65% of patients. All patients received streptozocin and Lipiodol. Carcinoid syndrome was improved in 69% of patients after treatment (p = 0.01). Post-embolization syndrome was reported in 78% of patients. At the end of all cTACE, objective response and non-progressive disease were 32% and 70%, respectively. Progression-free survival was 18.3 ± 13.3 months (median 14.9) and median overall survival (OS) from start of treatment was 74 months. The OS at 1 year, 2 years, 3 years and 5 years was 91% (IC = 84-99%), 84% (CI = 72-95%), 69% (CI = 53-84%) and 63% (C = 46-81%), respectively.

CONCLUSIONS

cTACE using streptozocin is an effective and well-tolerated palliative option for patients with neuroendocrine liver metastases, associated with prolonged survival and delayed time to progression.

A Comparison of the Outcomes of Transarterial Chemoembolization and Transarterial Radioembolization in the Management of Neuroendocrine Liver Metastases in Adults: A Systematic Review

The purpose of this article is to review the existing English scientific literature and determine the superior modality between transarterial chemoembolization (TACE) and radioembolization (TARE) in the treatment of neuroendocrine liver metastases (NELMs). To that end, we followed the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines to search PubMed, the Cochrane Library, and Google Scholar. We identified 14 observational studies and no randomized controlled trials (RCTs) investigating the use of TACE or TARE to treat NELM. We used the Newcastle-Ottawa Scale to assess the risk of bias in these studies. We concluded that TACE and TARE appeared to have similar outcomes when comparing overall survival, progression-free survival, radiological response, symptomatic response, and the incidence of severe adverse events. Further large-scale RCTs are needed to identify the superior modality conclusively. We also identified several unique prognostic factors for overall survival, such as the neutrophil-lymphocyte ratio, volumetric multiparametric magnetic resonance imaging, serum albumin, alkaline phosphatase, and pancreastatin.

Pancreatic neuroendocrine tumors: tailoring imaging to specific clinical scenarios

The clinical and imaging presentation of pancreatic neuroendocrine tumors (PanNETs) is variable and depends on tumor grade, stage, and functional status. This degree of variability combined with a multitude of treatment options and imaging modalities results in complexity when choosing the most appropriate imaging studies across various clinical scenarios. While various guidelines exist in the management and evaluation of PanNETs, there is an overall lack of consensus and detail regarding optimal imaging guidelines and protocols. This manuscript aims to fill gaps where current guidelines may lack specificity regarding the choice of the most appropriate imaging study in the diagnosis, treatment planning, monitoring, and surveillance of PanNETs under various clinical scenarios.

Radiation dose aspects and establishment of diagnostic reference levels for90Y radioembolisation during angiographic procedure

⁹⁰Y radioembolisation (RE) is an angiographic procedure used in patients with both primary and secondary hepatic malignancies. Local tumour control can be achieved by short range tumour irradiation by the regional intra-arterial administration of glass or resin microspheres loaded with 90yttrium that accumulate in the tumorous tissue. The aim of this study was to investigate the radiation exposure of RE and to establish a local diagnostic reference level (DRL). In this retrospective study, dose data from 397 procedures in 306 patients (mean age 67.4 ± 10.6 years, 82 female) who underwent RE between 06/2017 and 01/2022 using one of two different angiography systems were analysed. DRL was set as the 75th percentile of the dose distribution. In the overall population, dose area product (DAP) (median (interquartile range, IQR)) was 26 Gy cm²(IQR 12-50) with a median fluoroscopy time (FT) of 4.5 min (IQR 2.9-8.0). FT and DAP increased significantly with the number of infusion positions (median, IQR): one position 23 Gy cm²(12-46), two positions 33 Gy cm²(14-60), three positions 50 Gy cm²(24-82) (p< 0.0001). Local DRL is 47 Gy cm²for RE and 111 Gy cm²for RE with additional embolisation. Radiation exposure and FT are significantly higher with increasing number of infusion positions as well as additional embolisation. Our established DRLs for RE may serve as a benchmark for dose optimisation.

Using an Assumed Lung Mass Inaccurately Estimates the Lung Absorbed Dose in Patients Undergoing Hepatic 90Yttrium Radioembolization Therapy

RATIONALE

Currently, the estimated absorbed radiation dose to the lung in ⁹⁰Y radioembolization therapy is calculated using an assumed 1 kg lung mass for all patients. The aim of this study was to evaluate whether using a patient-specific lung mass measurement for each patient rather than a generic, assumed 1 kg lung mass would change the estimated lung absorbed dose.

METHODS

A retrospective analysis was performed on 68 patients who had undergone ⁹⁰Y radioembolization therapy at our institution. Individualized lung volumes were measured manually on CT scans for each patient, and these volumes were used to calculate personalized lung masses. The personalized lung masses were used to recalculate the estimated lung absorbed dose from the ⁹⁰Y therapy, and this dose was compared to the estimated lung absorbed dose calculated using an assumed 1 kg lung mass.

RESULTS

Patient-specific lung masses were significantly different from the generic 1 kg when compared individually for each patient (p < 0.0001). Median individualized lung mass was 0.71 (IQR: 0.59, 1.02) kg overall and was significantly different from the generic 1 kg lung mass for female patients [0.59 (0.50, 0.68) kg, (p < 0.0001)] but not for male patients [0.99 (0.71, 1.14) kg, (p = 0.24)]. Median estimated lung absorbed dose was 4.48 (2.38, 11.71) Gy using a patient-specific lung mass and 3.45 (1.81, 6.68) Gy when assuming a 1 kg lung mass for all patients. The estimated lung absorbed dose was significantly different using a patient-specific versus generic 1 kg lung mass when comparing the doses individually for each patient (p < 0.0001). The difference in the estimated lung absorbed dose between the patient-specific and generic 1 kg lung mass method was significant for female patients as a subgroup but not for male patients.

CONCLUSIONS

The current method of assuming a 1 kg lung mass for all patients inaccurately estimates the lung absorbed dose in ⁹⁰Y radioembolization therapy. Using patient-specific lung masses resulted in estimated lung absorbed doses that were significantly different from those calculated using an assumed 1 kg lung mass for all patients. A personalized dosimetry method that includes individualized lung masses is necessary and can warrant a ⁹⁰Y dose reduction in some patients with lung masses smaller than 1 kg.

LEVEL OF EVIDENCE

Level 3, Retrospective Study.

Role of Radioembolization in Metastatic Neuroendocrine Tumors

The liver is the most common site of metastasis for neuroendocrine tumors originating from the gastrointestinal tract. Neuroendocrine liver metastases (NELMs) portend a worsening clinical course, making local management important. Local treatment options include surgery, thermal ablation, and trans-catheter intra-arterial therapies, such as radioembolization. Radioembolization is generally preferred over other embolotherapies in patients with colonized biliary systems. Current best practice involves personalized treatment planning, optimizing tumor radiation absorbed dose and minimizing radiation to the normal hepatic parenchyma. As part of a multidisciplinary approach, radioembolization is a versatile embolotherapy offering neoadjuvant, palliative, and ablative treatment options for patients with NELMs.

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

Simple Summary

This review provides basic insights into radioembolization, also known as selective internal radiation therapy, in patients suffering from neuroendocrine liver metastases. Radioembolization is a treatment that uses radioactive beads that are implanted intra-arterially to locally irradiate liver tumors. The available literature on radioembolization in neuroendocrine liver metastases show promising results in terms of efficacy and toxicity and will be discussed in more detail. However, data in the field of NELM need clarification, and this review also discusses the caveats, challenges and new insights when considering radioembolization in neuroendocrine liver metastases.

Abstract

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.

Lung Dose Measured on Postradioembolization 90Y PET/CT and Incidence of Radiation Pneumonitis

Radiation pneumonitis is a rare but possibly fatal side effect of ⁹⁰Y radioembolization. It may occur 1-6 mo after therapy, if a significant part of the ⁹⁰Y microspheres shunts to the lungs. In current clinical practice, a predicted lung dose greater than 30 Gy is considered a criterion to exclude patients from treatment. However, contrasting findings regarding the occurrence of radiation pneumonitis and lung dose were previously reported in the literature. In this study, the relationship between the lung dose and the eventual occurrence of radiation pneumonitis after ⁹⁰Y radioembolization was investigated. Methods: We retrospectively analyzed 317 ⁹⁰Y liver radioembolization procedures performed during an 8-y period (February 2012 to September 2020). We calculated the predicted lung mean dose (LMD) using ^99mTc-MAA planar scintigraphy (LMD_MAA) acquired during the planning phase and left LMD (LMD_Y-90) using the ⁹⁰Y PET/CT acquired after the treatment. For the lung dose computation, we used the left lung as the representative lung volume, to compensate for scatter from the liver moving in the craniocaudal direction because of breathing and mainly affecting the right lung. Results: In total, 272 patients underwent ⁹⁰Y procedures, of which 63% were performed with glass microspheres and 37% with resin microspheres. The median injected activity was 1,974 MBq (range, 242-9,538 MBq). The median LMD_MAA was 3.5 Gy (range, 0.2-89.0 Gy). For 14 procedures, LMD_MAA was more than 30 Gy. Median LMD_Y-90 was 1 Gy (range, 0.0-22.1 Gy). No patients had an LMD_Y-90 of more than 30 Gy. Of the 3 patients with an LMD_Y-90 of more than 12 Gy, 2 patients (one with an LMD_Y-90 of 22.1 Gy and an LMD_MAA of 89 Gy; the other with an LMD_Y-90 of 17.7 Gy and an LMD_MAA of 34.1 Gy) developed radiation pneumonitis and consequently died. The third patient, with an LMD_Y-90 of 18.4 Gy (LMD_MAA, 29.1 Gy), died 2 mo after treatment, before the imaging evaluation, because of progressive disease. Conclusion: The occurrence of radiation pneumonitis as a consequence of a lung shunt after ⁹⁰Y radioembolization is rare (<1%). No radiation pneumonitis developed in patients with a measured LMD_Y-90 lower than 12 Gy.

Apparent diffusion coefficients (ADC) in response assessment of transarterial radioembolization (TARE) for liver metastases of neuroendocrine tumors (NET): a feasibility study

Background

In patients with hepatic neuroendocrine tumors (NETs) locoregional therapies such as transarterial radioembolization (TARE) are increasingly applied. Response evaluation remains challenging and previous studies assessing response with diffusion-weighted imaging (DWI) have been inconclusive.

Purpose

To perform a feasibility study to evaluate if response assessment with quantitative apparent diffusion coefficient (ADC) in patients with liver metastases of NETs after TARE will be possible.

Material and Methods

Retrospectively, 43 patients with 120 target lesions who obtained abdominal magnetic resonance imaging (MRI) with DWI 39±28 days before and 74±46 days after TARE were included. Intralesional ADC (ADC_min, ADC_max, and ADC_mean) were measured for a maximum number of three lesions per patient on baseline and post-interventional DWI. Tumor response was categorized according to RECIST 1.1 and mRECIST.

Results

TARE resulted in partial remission (PR) in 23% (63%), in stable disease (SD) in 73% (23%), in progressive disease (PD) in 5% (7%) and in complete response (CR) in 0% (1%) according to RECIST 1.1 (mRECIST, respectively). ADC values increased significantly (P<0.005) after TARE in the PR group whereas there was no significant change in the PD group. Post-therapeutic ADC values of SD lesions increased significantly when evaluated by RECIST 1.1 but not if evaluated by mRECIST. Percentual changes of ADC_mean values were slightly higher for responders compared to non-responders (P<0.05).

Conclusion

ADC values seem to represent an additional marker for treatment response evaluation after TARE in patients with secondary hepatic NET. A conclusive study seems feasible though patient-based evaluation and overall survival and progression free survival as alternate primary endpoints should be considered.

Radioembolization, Principles and indications

Radioembolization is the selective application of radionuclide-loaded microspheres into liver arteries for the therapy of liver tumours and metastases. In this review, we focused on therapy planning and dosimetry, as well as the main indications of 90Y-glass and resin microspheres and 166Ho-microspheres.

EANM procedure guideline for the treatment of liver cancer and liver metastases with intra-arterial radioactive compounds

Primary liver tumours (i.e. hepatocellular carcinoma (HCC) or intrahepatic cholangiocarcinoma (ICC)) are among the most frequent cancers worldwide. However, only 10-20% of patients are amenable to curative treatment, such as resection or transplant. Liver metastases are most frequently caused by colorectal cancer, which accounts for the second most cancer-related deaths in Europe. In both primary and secondary tumours, radioembolization has been shown to be a safe and effective treatment option. The vast potential of personalized dosimetry has also been shown, resulting in markedly increased response rates and overall survival. In a rapidly evolving therapeutic landscape, the role of radioembolization will be subject to changes. Therefore, the decision for radioembolization should be taken by a multidisciplinary tumour board in accordance with the current clinical guidelines. The purpose of this procedure guideline is to assist the nuclear medicine physician in treating and managing patients undergoing radioembolization treatment. PREAMBLE: The European Association of Nuclear Medicine (EANM) is a professional non-profit medical association that facilitates communication worldwide among individuals pursuing clinical and research excellence in nuclear medicine. The EANM was founded in 1985. These guidelines are intended to assist practitioners in providing appropriate nuclear medicine care for patients. They are not inflexible rules or requirements of practice and are not intended, nor should they be used, to establish a legal standard of care. The ultimate judgment regarding the propriety of any specific procedure or course of action must be made by medical professionals taking into account the unique circumstances of each case. Thus, there is no implication that an approach differing from the guidelines, standing alone, is below the standard of care. To the contrary, a conscientious practitioner may responsibly adopt a course of action different from that set out in the guidelines when, in the reasonable judgment of the practitioner, such course of action is indicated by the condition of the patient, limitations of available resources or advances in knowledge or technology subsequent to publication of the guidelines. The practice of medicine involves not only the science but also the art of dealing with the prevention, diagnosis, alleviation and treatment of disease. The variety and complexity of human conditions make it impossible to always reach the most appropriate diagnosis or to predict with certainty a particular response to treatment. Therefore, it should be recognised that adherence to these guidelines will not ensure an accurate diagnosis or a successful outcome. All that should be expected is that the practitioner will follow a reasonable course of action based on current knowledge, available resources and the needs of the patient to deliver effective and safe medical care. The sole purpose of these guidelines is to assist practitioners in achieving this objective.

Orchestrating Treatment Modalities in Metastatic Pancreatic Neuroendocrine Tumors-Need for a Conductor

Simple Summary

Pancreatic neuroendocrine tumors (pNET) are a heterogeneous and challenging entity, and today’s guidelines offer a variety of treatment modalities, while surgery has a clear role for patients with resectable tumors and early stages, advanced, or metastatic pNET may benefit from treatments that were evaluated in randomized controlled studies during the last year. With this review, we aim to provide an updated view on treatment options for metastatic pNET.

Abstract

Pancreatic neuroendocrine tumors (pNETs) are a vast growing disease. Over 50% of these tumors are recognized at advanced stages with lymph node, liver, or distant metastasis. An ongoing controversy is the role of surgery in the metastatic setting as dedicated systemic treatments have emerged recently and shown benefits in randomized trials. Today, liver surgery is an option for advanced pNETs if the tumor has a favorable prognosis, reflected by a low to moderate proliferation index (G1 and G2). Surgery in this well-selected population may prolong progression-free and overall survival. Optimal selection of a treatment plan for an individual patient should be considered in a multidisciplinary tumor board. However, while current guidelines offer a variety of modalities, there is so far only a limited focus on the right timing. Available data is based on small case series or retrospective analyses. The focus of this review is to highlight the right time-point for surgery in the setting of the multimodal treatment of an advanced pancreatic neuroendocrine tumor.

Predictive Factors for Resistant Disease with Medical/Radiologic/Liver-Directed Anti-Tumor Treatments in Patients with Advanced Pancreatic Neuroendocrine Neoplasms: Recent Advances and Controversies

Simple Summary

Tumor resistance, both primary and acquired, is leading to increased complexity in the nonsurgical treatment of patients with advanced panNENs, which would be greatly helped by reliable prognostic/predictive factors. The importance in identifying resistance is being contributed to by the increased array of possible treatments available for treating resistant advanced disease; the variable clinical course as well as response to any given treatment approach of patients within one staging or grading system, the advances in imaging which are providing increasing promising results/parameters that correlate with grading/outcome/resistance, the increased understanding of the molecular pathogenesis providing promising prognostic markers, all of which can contribute to selecting the best treatment to overcome resistance disease. Several factors have been identified that have prognostic/predictive value for identifying development resistant disease and affecting overall survival (OS)/PFS with various nonsurgical treatments of patients with advanced panNENs. Prognostic factors identified for patients with advanced panNENs for both OS/PFSs include various clinically-related factors (clinical, laboratory/biological markers, imaging, treatment-related factors), pathological factors (histological, classification, grading) and molecular factors. Particularly important prognostic factors for the different treatment modalities studies are the recent grading systems. Most prognostic factors for each treatment modality for OS/PFS are not specific for a given treatment option. These advances have generated several controversies and new unanswered questions, particularly those related to their possible role in predicting the possible sequence of different anti-tumor treatments in patients with different presentations. Each of these areas is reviewed in this paper.

Abstract

Purpose: Recent advances in the diagnosis, management and nonsurgical treatment of patients with advanced pancreatic neuroendocrine neoplasms (panNENs) have led to an emerging need for sensitive and useful prognostic factors for predicting responses/survival. Areas covered: The predictive value of a number of reported prognostic factors including clinically-related factors (clinical/laboratory/imaging/treatment-related factors), pathological factors (histological/classification/grading), and molecular factors, on therapeutic outcomes of anti-tumor medical therapies with molecular targeting agents (everolimus/sunitinib/somatostatin analogues), chemotherapy, radiological therapy with peptide receptor radionuclide therapy, or liver-directed therapies (embolization/chemoembolization/radio-embolization (SIRTs)) are reviewed. Recent findings in each of these areas, as well as remaining controversies and uncertainties, are discussed in detail, particularly from the viewpoint of treatment sequencing. Conclusions: The recent increase in the number of available therapeutic agents for the nonsurgical treatment of patients with advanced panNENs have raised the importance of prognostic factors predictive for therapeutic outcomes of each treatment option. The establishment of sensitive and useful prognostic markers will have a significant impact on optimal treatment selection, as well as in tailoring the therapeutic sequence, and for maximizing the survival benefit of each individual patient. In the paper, the progress in this area, as well as the controversies/uncertainties, are reviewed.

Inflammatory markers and long term hematotoxicity of holmium-166-radioembolization in liver-dominant metastatic neuroendocrine tumors after initial peptide receptor radionuclide therapy

Purpose

In patients with neuroendocrine tumor liver metastases, additional tumor reduction can be achieved by sequential treatment with [¹⁶⁶Ho]-radioembolization after peptide receptor radionuclide therapy (PRRT). The aim of this study was to analyze hematotoxicity profiles, (i.e. lymphocyte and neutrophile toxicity) and the prognostic value of neutrophil-to-lymphocyte ratio (NLR) and thrombocyte-to-lymphocyte ratio (TLR).

Methods

All patients included in the prospective HEPAR PLuS study were included in this study. Blood testing was performed at baseline (before radioembolization) and at regular intervals during 1-year follow-up. Radiological response was assessed at 3, 6, 9, and 12 months according to RECIST 1.1. Logistic regression was used to analyze the prognostic value of NLR and TLR on response.

Results

Thirty-one patients were included in the toxicity analysis; thirty were included in the response analysis. Three weeks after radioembolization, a significant decrease in lymphocyte count (mean change − 0.26 × 10⁹/L) was observed. Ten patients (32.2%) experienced grade 3–4 lymphocyte toxicity. This normalized at 6 weeks and 3 months after treatment, while after 6 months a significant increase in lymphocyte count was observed. An increase in NLR and TLR at 3 weeks, compared to baseline, significantly predicted response at 3 months (AUC = 0.841 and AUC = 0.839, respectively) and at 6 months (AUC = 0.779 and AUC = 0.765). No significant relation with survival was found.

Conclusions

Toxicity after sequential treatment with PRRT and [¹⁶⁶Ho]-radioembolization is limited and temporary, while significant additional benefit can be expected. Change in NLR and TLR at 3-weeks follow-up may be valuable early predictors of response.

Trial registration ClinicalTrials.gov, NCT02067988. Registered 20 February 2014, https://clinicaltrials.gov/ct2/show/record/NCT02067988.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13550-022-00880-4.

Dose-response relationship after yttrium-90-radioembolization with glass microspheres in patients with neuroendocrine tumor liver metastases

BACKGROUND

In radioembolization, response is achieved through the irradiation and damaging of tumor DNA. For hepatic metastases of neuroendocrine tumors, a dose-response relationship has not been established yet. This study assesses whether increasing tumor-absorbed doses lead to increased response rates.

METHODS

We included all patients who underwent yttrium-90 (⁹⁰Y) glass microspheres radioembolization in our center if both pre- and post-treatment contrast-enhanced CT and post-injection PET/CT were available. Up to five hepatic tumors and the healthy hepatic tissue were delineated, and absorbed dose was quantified using post-injection PET/CT. Response was measured according to RECIST 1.1 on patient and tumor level. Linear mixed models were used to study the relationship between absorbed dose and response on tumor level. Logistic regression analysis was used on patient level to study dose-response and hepatic dose-toxicity relationships.

RESULTS

A total of 128 tumors in 26 patients (31 procedures) were included in the response analysis. While correcting for confounding by tumor volume, a significant effect of response on dose was found (p = 0.0465). Geometric mean of absorbed dose for responding tumors was 170 Gy, for stable disease 101 Gy, and for progressive disease 67 Gy. No significant dose-toxicity relationship could be identified.

CONCLUSION

In patients with neuroendocrine tumor liver metastases, treated with ⁹⁰Y-radioembolization, a clear dose-response relationship was found. We propose to perform ⁹⁰Y-radioembolization with an absolute minimum planned tumor-absorbed dose of 150 Gy.

Radioembolization of Secondary Hepatic Malignancies

Cancer has become the leading cause of mortality in America, and the majority of patients eventually develop hepatic metastasis. As liver metastases are frequently unresectable, the value of liver-directed therapies, such as transarterial radioembolization (TARE), has become increasingly recognized as an integral component of patient management. Outcomes after radioembolization of hepatic malignancies vary not only by location of primary malignancy but also by tumor histopathology. This article reviews the outcomes of TARE for the treatment of metastatic colorectal cancer, metastatic breast cancer, and metastatic neuroendocrine tumors, as well as special considerations when treating metastatic disease with TARE.

68Ga-DOTATATE PET/CT and MRI with Diffusion-Weighted Imaging (DWI) in Short- and Long-Term Assessment of Tumor Response of Neuroendocrine Liver Metastases (NELM) Following Transarterial Radioembolization (TARE)

Simple Summary

TARE with ⁹⁰Yttrium has become a valuable treatment option for patients with unresectable NELMs. However, early evaluation of therapy response remains challenging as size-based response assessments (such as RECIST) are known to be limited, especially in slow-growing tumors. Alternatives such as quantitative evaluation of SUV of ⁶⁸Ga-DOTATATE PET/CT and ADC of DWI-MRI have not been compared so far. We found that early percentage changes in SUV tumor-to-organ ratios on first follow-up after TARE could predict longer HPFS in patients with NELM and were superior to ΔSUVmax/SUVmean alone or to ΔADC.

Abstract

The aim of this study was to evaluate the role of SUV and ADC in assessing early response in patients with NELM following TARE. Thirty-two patients with pre- and postinterventional MRI with DWI and ⁶⁸Ga-DOTATATE PET/CT were included. ADC and SUV of three target lesions and of tumor-free spleen and liver tissue were determined on baseline and first follow-up imaging, and tumor to spleen (T/S) and tumor to liver (T/L) ratios were calculated. Response was assessed by RECIST 1.1 and mRECIST on first follow-up, and long-term response was defined as hepatic progression-free survival (HPFS) over 6, 12, and <24 months. In responders, intralesional ADC values increased and SUV decreased significantly regardless of standard of reference for response assessment (mRECIST/RECIST/HPFS > 6/12/24 m). Using ROC analysis, ΔSUV T/S ratio (max/max) and ΔSUV T/L ratio (max/mean) were found to be the best and most robust metrics to correlate with longer HPFS and were superior to ΔADC. ΔT/S ratio (max/max) < 23% was identified as an optimal cut-off to discriminate patients with longer HPFS (30.2 m vs. 13.4 m; p = 0.0002). In conclusion, early percentage changes in SUV tumor-to-organ ratios on first follow-up seem to represent a prognostic marker for longer HPFS and may help in assessing therapeutic strategies.

Reassessment of the lung dose limits for radioembolization

Radioembolization, also known as selective internal radiation therapy (SIRT), is an established treatment for the management of patients with unresectable liver tumors. Advances in liver dosimetry and new knowledge about tumor dose-response relationships have helped promote the well-tolerated use of higher prescribed doses, consequently transitioning radioembolization from palliative to curative therapy. Lung dosimetry, unfortunately, has not seen the same advances in dose calculation methodology and renewed consensus in dose limits as normal liver and tumor dosimetry. Therefore, the efficacy of curative radioembolization may be compromised in patients where the current lung dose calculations unnecessarily limit the administered activity. The field is thus at a stage where a systematic review and update of lung dose limits is necessary to advance the clinical practice of radioembolization. This work summarizes the historical context and literature for origins of the current lung dose limits following radioembolization, that is, the 25-year-old, single institution, small patient cohort series that helped establish the lung shunt fraction and dose limits. Newer clinical evidence based on larger patient cohorts that challenges the historical data on lung dose limits are then discussed. We conclude by revisiting the rationale for current lung dose limits and by proposing a staged approach to advance the field of lung dosimetry and thus the practice of radioembolization as a whole.

International recommendations for personalised selective internal radiation therapy of primary and metastatic liver diseases with yttrium-90 resin microspheres

PURPOSE

A multidisciplinary expert panel convened to formulate state-of-the-art recommendations for optimisation of selective internal radiation therapy (SIRT) with yttrium-90 (90Y)-resin microspheres.

METHODS

A steering committee of 23 international experts representing all participating specialties formulated recommendations for SIRT with 90Y-resin microspheres activity prescription and post-treatment dosimetry, based on literature searches and the responses to a 61-question survey that was completed by 43 leading experts (including the steering committee members). The survey was validated by the steering committee and completed anonymously. In a face-to-face meeting, the results of the survey were presented and discussed. Recommendations were derived and level of agreement defined (strong agreement ≥ 80%, moderate agreement 50%-79%, no agreement ≤ 49%).

RESULTS

Forty-seven recommendations were established, including guidance such as a multidisciplinary team should define treatment strategy and therapeutic intent (strong agreement); 3D imaging with CT and an angiography with cone-beam-CT, if available, and 99mTc-MAA SPECT/CT are recommended for extrahepatic/intrahepatic deposition assessment, treatment field definition and calculation of the 90Y-resin microspheres activity needed (moderate/strong agreement). A personalised approach, using dosimetry (partition model and/or voxel-based) is recommended for activity prescription, when either whole liver or selective, non-ablative or ablative SIRT is planned (strong agreement). A mean absorbed dose to non-tumoural liver of 40 Gy or less is considered safe (strong agreement). A minimum mean target-absorbed dose to tumour of 100-120 Gy is recommended for hepatocellular carcinoma, liver metastatic colorectal cancer and cholangiocarcinoma (moderate/strong agreement). Post-SIRT imaging for treatment verification with 90Y-PET/CT is recommended (strong agreement). Post-SIRT dosimetry is also recommended (strong agreement).

CONCLUSION

Practitioners are encouraged to work towards adoption of these recommendations.

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.

A Comparison of Liver-Directed Therapy and Systemic Therapy for the Treatment of Liver Metastases in Patients with Gastrointestinal Neuroendocrine Tumors: Analysis of the California Cancer Registry

PURPOSE

To compare the outcomes of patients with gastrointestinal neuroendocrine tumor liver metastases treated with liver-directed therapy (LDT) to those treated with systemic therapy (ST) in a statewide cancer database.

MATERIALS AND METHODS

A retrospective study was performed of patients with metastatic gastrointestinal tract neuroendocrine tumors treated with either LDT or ST alone between the years 2000-2012 in the California Cancer Registry. Overall survival and disease-specific survival were assessed using multivariable Cox proportional hazards analysis and propensity score matching.

RESULTS

A total of 154 patients (ST, n = 87 and LDT, n = 67) were studied. The median overall survival and disease-specific survival for patients that received ST was 29 and 35 months versus 51 and >60 months for patients that received LDT. On multivariate analysis, LDT and the resection of the primary tumor were associated with improved survival (hazard ratio [HR] 0.52, P = .002; HR 0.43, P = .001). Non-white race, Medicaid/uninsured status, and the presence of lung metastases were associated with poor survival (HR 1.76, P = .014; HR 2.29, P = .009; and HR 1.79, P = .031). Propensity score matching demonstrated an improvement in disease-specific survival for LDT compared to ST (HR 0.53, P = .036). The improvement in overall survival on propensity score matching did not achieve statistical significance (HR 0.70, P = .199).

CONCLUSIONS

LDT is associated with improved overall and disease-specific survival as compared to ST in patients with gastrointestinal neuroendocrine tumor liver metastases. Further investigation is needed to determine whether combination or sequential treatment can improve outcomes in this population.

Lung shunt and lung dose calculation methods for radioembolization treatment planning

Radioembolization, also known as selective internal radiation therapy (SIRT), is firmly established in the management of patients with unresectable liver cancers. Advances in normal and tumor liver dosimetry and new knowledge about tumor dose response relationships have helped promote the safe use of higher prescribed doses, consequently transitioning radioembolization from palliative to curative therapy. The lungs are considered a critical organ of risk for radioembolization treatment planning. Unfortunately, lung dosimetry has not achieved similar advances in dose calculation methodology as liver dosimetry. Current estimations of lung dose are dependent on a number of parameters associated with data acquisition and processing algorithms, leading to poor accuracy and precision. Therefore, the efficacy of curative radioembolization may be compromised in patients for whom the lung dose derived using currently available methods unnecessarily limits the desired administered activity to the liver. We present a systematic review of the various methods of determining the lung shunt fraction (LSF) and lung mean dose (LD). This review encompasses pretherapy estimations and post-therapy assessments of the LSF and LD using both 2D planar and 3D SPECT/CT based calculations. The advantages and limitations of each of these methods are deliberated with a focus on accuracy and practical considerations. We conclude the review by presenting a lexicon to precisely describe the methodology used for the estimation of LSF and LD; specifically, category, agent, modality, contour and algorithm, in order to aid in their interpretation and standardization in routine clinical practice.

Modern therapeutic approaches for the treatment of malignant liver tumours

Malignant liver tumours include a wide range of primary and secondary tumours. Although surgery remains the mainstay of curative treatment, modern therapies integrate a variety of neoadjuvant and adjuvant strategies and have achieved dramatic improvements in survival. Extensive tumour loads, which have traditionally been considered unresectable, are now amenable to curative treatment through systemic conversion chemotherapies followed by a variety of interventions such as augmentation of the healthy liver through portal vein occlusion, staged surgeries or ablation modalities. Liver transplantation is established in selected patients with hepatocellular carcinoma but is now emerging as a promising option in many other types of tumour such as perihilar cholangiocarcinomas, neuroendocrine or colorectal liver metastases. In this Review, we summarize the available therapies for the treatment of malignant liver tumours, with an emphasis on surgical and ablative approaches and how they align with other therapies such as modern anticancer drugs or radiotherapy. In addition, we describe three complex case studies of patients with malignant liver tumours. Finally, we discuss the outlook for future treatment, including personalized approaches based on molecular tumour subtyping, response to targeted drugs, novel biomarkers and precision surgery adapted to the specific tumour.

Efficacy and safety of Yttrium-90 radioembolization in the treatment of neuroendocrine liver metastases. Long-term monitoring and impact on survival

INTRODUCTION AND OBJECTIVE

Neuroendocrine tumors (NETs) debut in 75% of cases with liver metastases (LMNETs), whose therapeutic approach includes surgical resection and liver transplantation, while liver radioembolization with 90 Y-microspheres (TARE) is reserved for non-operable patients usually due to high tumor burden. We present the accumulated experience of 10 years in TARE treatment of LMNETs in order to describe the safety and the effectiveness of the oncological response in terms of survival, as well as to detect the prognostic factors involved.

MATERIAL AND METHODS

Of 136 TARE procedures, performed between January 2006 and December 2016, 30 LMNETs (11.1%) were retrospectively analyzed. The study variables were: Tumor response, time to liver progression, survival at 3 and 5 years, overall mortality and mortality associated with TARE. The radiological response assessment was assessed using RECIST 1.1 and mRECIST criteria.

RESULTS

An average activity of 2.4 ± 1.3 GBq of 90 Y was administered. No patient presented postembolization syndrome or carcinoid syndrome. There were also no vascular complications associated with the procedure. According to RECIST 1.1 criteria at 6 months, 78.6% presented partial response and 21.4% stable disease, there was no progression or complete response (1 by mRECIST). Survival at 3 and 5 years was 73% in both cases.

CONCLUSION

TARE treatment with 90 Y-microspheres in LMNETs, applied within a multidisciplinary approach, is a safe procedure, with low morbidity, capable of achieving a high rate of radiological response and achieving lasting tumor responses.

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.

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.

Quantitative 166Ho-microspheres SPECT derived from a dual-isotope acquisition with 99mTc-colloid is clinically feasible

Purpose

Accurate dosimetry is essential in radioembolization. To this purpose, an automatic protocol for healthy liver dosimetry based on dual isotope (DI) SPECT imaging, combining holmium-166 (¹⁶⁶Ho)-microspheres, and technetium-99 m (^99mTc)-colloid was developed: ¹⁶⁶Ho-microspheres used as scout and therapeutic particles, and ^99mTc-colloid to identify the healthy liver. DI SPECT allows for an automatic and accurate estimation of absorbed doses, introducing true personalized dosimetry. However, photon crosstalk between isotopes can compromise image quality. This study investigates the effect of ^99mTc downscatter on ¹⁶⁶Ho dosimetry, by comparing ¹⁶⁶Ho-SPECT reconstructions of patient scans acquired before (¹⁶⁶Ho-only) and after additional administration of ^99mTc-colloid (¹⁶⁶Ho-DI).

Methods

The ¹⁶⁶Ho-only and ¹⁶⁶Ho-DI scans were performed in short succession by injecting ^99mTc-colloid on the scanner table. To compensate for ^99mTc downscatter, its influence was accounted for in the DI image reconstruction using energy window-based scatter correction methods. The qualitative assessment was performed by independent blinded comparison by two nuclear medicine physicians assessing 65 pairs of SPECT/CT. Inter-observer agreement was tested by Cohen’s kappa coefficient. For the quantitative analysis, two volumes of interest within the liver, VOI_TUMOR, and VOI_HEALTHY were manually delineated on the ¹⁶⁶Ho-only reconstruction and transferred to the co-registered ¹⁶⁶Ho-DI reconstruction. Absorbed dose within the resulting VOIs, and in the lungs (VOI_LUNGS), was calculated based on the administered therapeutic activity.

Results

The qualitative assessment showed no distinct clinical preference for either ¹⁶⁶Ho-only or ¹⁶⁶Ho-DI SPECT (kappa = 0.093). Quantitative analysis indicated that the mean absorbed dose difference between ¹⁶⁶Ho-DI and ¹⁶⁶Ho-only was − 2.00 ± 2.84 Gy (median 27 Gy; p value < 0.00001), − 5.27 ± 8.99 Gy (median 116 Gy; p value = 0.00035), and 0.80 ± 1.08 Gy (median 3 Gy; p value < 0.00001) for VOI_HEALTHY, VOI_TUMOR, and VOI_LUNGS, respectively. The corresponding Pearson’s correlation coefficient between ¹⁶⁶Ho-only and ¹⁶⁶Ho-DI for absorbed dose was 0.97, 0.99, and 0.82, respectively.

Conclusion

The DI protocol enables automatic dosimetry with undiminished image quality and accuracy.

Clinical trials

The clinical study mentioned is registered with Clinicaltrials.gov (NCT02067988) on 20 February 2014.

Radioembolization for neuroendocrine liver metastases is safe and effective prior to major hepatic resection

Background

Radioembolization (RE) is well established in the treatment of neuroendocrine liver metastases. However surgery is rarely performed after RE, although liver resection is the gold standard in the treatment of localized neuroendocrine liver metastases. Therefore, aim of the present study was to evaluate the safety and feasibility of liver resection after RE in a homogenous cohort.

Methods

From a prospective surgical (n=494) and nuclear medical (n=138) database patients with NELM who underwent liver resection and/or RE were evaluated. Between September 2011 and December 2017 eight patients could be identified who underwent liver resection after RE (mean therapeutic activity of 1,746 Mbq). Overall and progression free survival were evaluated as well as epidemiological and perioperative factors. The surgical specimens were analyzed for necrosis, fibrosis, inflammation, and steatosis.

Results

The mean hepatic tumor load of patients, who had liver surgery after RE, was 31.4% with a mean Ki-67 proliferation index of 5.9%. The majority of these patients (7/8) received whole liver RE prior to liver resection, which did not increase morbidity and mortality compared to a surgical collective. Indications for RE were oncological (6/8) or carcinoid syndrome associated reasons (2/8). Mean overall survival was 25.1 months after RE and subsequent surgery. Tumor necrosis in radioembolized lesions was 29.4% without evidence of fibrosis and inflammation in hepatic tissue.

Conclusions

This is the first study analyzing the multimodal therapeutic approach of liver resection following whole liver RE. This treatment algorithm is safe, does not lead to an increased morbidity and is associated with a favorable oncological outcome. Nonetheless, patient selection remains a key issue.

Transarterial Radioembolization for Hepatocellular Carcinoma and Hepatic Metastases: Clinical Aspects and Dosimetry Models

Transarterial radioembolization (TARE) with Yttrium-90 (⁹⁰Y) microspheres is a liver-directed therapy for primary and metastatic disease. This manuscript provides a review of the clinical literature on TARE indications and efficacy with overviews of patient-selection and toxicity. Current dosimetry models used in practice are safe, relatively simple, and easy for clinicians to use. Planning currently relies on the imperfect surrogate, ^99mTc macroaggregated albumin. Post-therapy quantitative imaging (⁹⁰Y SPECT/CT or ⁹⁰Y PET/CT) of microspheres can be used to calculate the macroscopic in vivo absorbed dose distribution. Similar to the evolution of other brachytherapy dose calculations, TARE is moving toward more patient-specific dosimetry that includes calculating and reporting nonuniform dose distributions throughout tumors and normal uninvolved liver.

Interventional Liver-Directed Therapy for Neuroendocrine Metastases: Current Status and Future Directions

OPINION STATEMENT

Liver-directed therapy should be considered for patients with unresectable liver metastases from neuroendocrine tumor if symptomatic or progressing despite medical management. Our experience and current literature shows that the bland embolization, chemoembolization, and radioembolization are very effective in controlling symptoms and disease burden in the liver, and that these embolization modalities are similar in terms of efficacy and radiologic response. Their safety profiles differ, however, with recent studies suggesting an increase in biliary toxicity with drug-eluting bead chemoembolization over conventional chemoembolization, and a risk of long-term hepatotoxicity with radioembolization. For this reason, we tailor the type of embolotherapy to each patient according to their clinical status, symptoms, degree of tumor burden, histologic grade, and life expectancy. We do not recommend a "one-size-fits-all" approach. Our general strategy is to use bland embolization as first-line embolotherapy, and radioembolization for patients with high-grade tumors or who have failed other embolotherapy.

Additional holmium-166 radioembolisation after lutetium-177-dotatate in patients with neuroendocrine tumour liver metastases (HEPAR PLuS): a single-centre, single-arm, open-label, phase 2 study

BACKGROUND

In patients with metastatic neuroendocrine neoplasms, the liver is the most commonly affected organ and a crucial factor for prognosis and survival. Peptide receptor radionuclide therapy can prolong progression-free survival in these patients. Additional treatment of liver disease might further improve outcomes. We aimed to investigate the safety and efficacy of additional holmium-166 (¹⁶⁶Ho) radioembolisation after peptide receptor radionuclide therapy in patients with metastatic liver neuroendocrine neoplasms.

METHODS

The Holmium Embolization Particles for Arterial Radiotherapy Plus ¹⁷⁷Lu-Dotatate in Salvage Neuroendocrine Tumour Patients (HEPAR PLuS) study was a single-centre, phase 2 study done at the University Medical Center Utrecht (Utrecht, Netherlands). Patients, aged at least 18 years, with histologically proven grade 1 or 2 neuroendocrine neoplasms of all origins, an Eastern Cooperative Oncology Group performance status of 0-2, and three or more measurable liver metastases according to Response Evaluation Criteria In Solid Tumors (RECIST) version 1.1 criteria received ¹⁶⁶Ho-radioembolisation within 20 weeks after four cycles of peptide receptor radionuclide therapy (lutetium-177-dotatate [¹⁷⁷Lu-dotatate]). The primary endpoint was objective liver tumour response in the treated liver volume, defined as complete response (disappearance of all lesions) or partial response (≥30% decrease in the sum of the longest diameters of the target lesions, compared with baseline measurements), according to RECIST 1.1, analysed per protocol at 3 months. Safety was assessed in all patients who received treatment. This study is registered with ClinicalTrials.gov, NCT02067988. Recruitment is completed and long-term follow-up is ongoing.

FINDINGS

From Oct 15, 2014, to Sept 12, 2018, 34 patients were assessed for eligibility. 31 patients received treatment and 30 (97%) patients were available for primary endpoint assessment and completed 6 months of follow-up. Three (9%) patients were excluded at screening and one (3%) patient was treated and died before the primary endpoint and was replaced. According to the per-protocol analysis 13 (43%; 95% CI 26-63) of 30 patients achieved an objective response in the treated volume. The most frequently reported Common Terminology Criteria for Adverse Events (CTCAE) grade 3-4 clinical and laboratory toxicities within 6 months included abdominal pain (three [10%] of 31 patients), increased γ-glutamyl transpeptidase (16 [54%]), and lymphocytopenia (seven [23%]). One (3%) fatal treatment-related serious adverse event occurred (radioembolisation-induced liver disease). Two (6%) patients had serious adverse events deemed to be unrelated to treatment (gastric ulcer and perforated cholecystitis).

INTERPRETATION

¹⁶⁶Ho-radioembolisation, as an adjunct to peptide receptor radionuclide therapy in patients with neuroendocrine neoplasm liver metastases, is safe and efficacious. Radioembolisation can be considered in patients with bulky liver disease, including after peptide receptor radionuclide therapy. A future randomised, controlled study should investigate the added benefit of this treatment on progression-free survival.

FUNDING

None.

Intra-arterial versus standard intravenous administration of lutetium-177-DOTA-octreotate in patients with NET liver metastases: study protocol for a multicenter, randomized controlled trial (LUTIA trial)

BACKGROUND

Lutetium-177-DOTA-octreotate (¹⁷⁷Lu-DOTATATE) significantly increases survival and response rates in patients with grade I and grade II neuroendocrine tumors (NETs). However, survival and response rates are significantly lower in patients with bulky liver metastases. Increasing the tumor-absorbed dose in liver metastases may improve response to ¹⁷⁷Lu-DOTATATE. The LUTIA (Lutetium Intra-Arterial) study aims to increase the tumor-absorbed dose in liver metastases by intra-arterial (IA) administration of ¹⁷⁷Lu-DOTATATE, compared to conventional intravenous (IV) administration.

METHODS

A multicenter, within-patient randomized controlled trial (RCT) in 26 patients with progressive, liver-dominant, unresectable grade I or grade II NET will be conducted. Patients with bilobar bulky disease will be randomly allocated to receive IA treatment into either the left or the right hepatic artery. Using this approach, one liver lobe will be treated intra-arterially (first-pass effect), while the contralateral lobe will receive an intravenous treatment as a second-pass effect. The primary endpoint of this study is the difference in tumor-to-non-tumor ratio of ¹⁷⁷Lu-DOTATATE uptake between the two liver lobes on post-treatment SPECT/CT (IA versus IV). Secondary endpoints include absorbed dose in both liver lobes, tumor response, dose-response relationship, toxicity, uptake in extrahepatic lesions, and renal uptake.

DISCUSSION

This multicenter, within-patient RCT will investigate whether IA administration of ¹⁷⁷Lu-DOTATATE results in a higher activity concentration in liver metastases compared to IV administration.

TRIAL REGISTRATION

ClinicalTrials.gov, NCT03590119. Registered on 17 July 2018.

Transarterial Chemoembolization vs Radioembolization for Neuroendocrine Liver Metastases: A Multi-Institutional Analysis

BACKGROUND

Liver-directed hepatic arterial therapies are associated with improved survival and effective symptom control for patients with unresectable neuroendocrine liver metastases (NELM). Whether transarterial chemoembolization (TACE) or transarterial radioembolization (TARE) with yttrium-90 (y-90) are associated with improved short- or long-term outcomes is unknown.

STUDY DESIGN

A retrospective review was performed of all patients with NELM undergoing transarterial therapies, from 2000 to 2018, at 2 academic medical centers. Postoperative morbidity, radiographic response according to response evaluation criteria in solid tumors (RECIST) criteria, and long-term outcomes were compared between patients who underwent TACE vs TARE.

RESULTS

Among 248 patients with NELM, 197 (79%) received TACE and 51 (21%) received TARE. While patients who underwent TACE were more likely to have carcinoid syndrome, larger tumors, and higher chromogranin A levels, there was no difference in tumor differentiation, primary site, bilobar disease, or synchronous presentation. Nearly all TARE treatments (92%) were performed as outpatient procedures, while 99% of TACE patients spent at least 1 night in the hospital. There were no differences in overall morbidity (TARE 13.7% vs TACE 22.6%, p = 0.17), grade III/IV complication (5.9% vs 9.2%, p = 0.58), or 90-day mortality. The disease control rate (DCR) on first post-treatment imaging (RECIST partial/complete response or stable disease) was greater for TACE compared with TARE (96% vs 83%, p < 0.01). However, there was no difference in median overall survival (OS, 35.9 months vs 50.1 months, p = 0.3) or progression-free survival (PFS, 15.9 months vs 19.9 months, p = 0.37).

CONCLUSIONS

In this retrospective multi-institutional analysis, both TACE and TARE with Y-90 were safe and effective liver-directed therapies for unresectable NELM. Although TARE was associated with a shorter length of hospital stay, TACE demonstrated improved short-term DCR, and both resulted in comparable long term outcomes.

Neuroendocrine Neoplasms of the Small Bowel and Pancreas

The traditionally promulgated perspectives of neuroendocrine neoplasms (NEN) as rare, indolent tumours are blunt and have been outdated for the last 2 decades. Clear increments in their incidence over the past decades render them increasingly clinically relevant, and at initial diagnosis many present with nodal and/or distant metastases (notably hepatic). The molecular pathogenesis of these tumours is increasingly yet incompletely understood. Those arising from the small bowel (SB) or pancreas typically occur sporadically; the latter may occur within the context of hereditary tumour predisposition syndromes. NENs can also be associated with endocrinopathy of hormonal hypersecretion. Tangible advances in the development of novel biomarkers, functional imaging modalities and therapy are especially applicable to this sub-set of tumours. The management of SB and pancreatic neuroendocrine tumours (NET) may be challenging, and often comprises a multidisciplinary approach wherein surgical, medical, interventional radiological and radiotherapeutic modalities are implemented. This review provides a comprehensive overview of the epidemiology, pathophysiology, diagnosis and treatment of SB and pancreatic NETs. Moreover, we provide an outlook of the future in these tumour types which will include the development of precision oncology frameworks for individualised therapy, multi-analyte predictive biomarkers, artificial intelligence-derived clinical decision support tools and elucidation of the role of the microbiome in NEN development and clinical behaviour.

Optimization of the radiolabelling method for improved in vitro and in vivo stability of 90Y-albumin microspheres

Biologically stable ⁹⁰Y-labelled albumin microspheres (AMS) were developed by optimizing the process of their preparation. Three formulations of ⁹⁰Y-AMS were initially prepared with high radiolabelling yield but depending on the step when the radionuclide ⁹⁰Y and DTPA chelator were added, radiolabelled microspheres with different in vitro and in vivo stability were obtained. DTPA was proved as a useful chelating agent that tightly links radionuclide ⁹⁰Y to albumin. Also, AMS radiolabelled via DTPA during preparation and before microspheres stabilization, showed significant in vitro and in vivo stability ready for the potential use in selective internal radiation therapy.

Radioembolization with 90Y Resin Microspheres of Neuroendocrine Liver Metastases After Initial Peptide Receptor Radionuclide Therapy

Purpose

Peptide receptor radionuclide therapy (PRRT) and radioembolization are increasingly used in neuroendocrine neoplasms patients. However, concerns have been raised on cumulative hepatotoxicity. The aim of this sub-analysis was to investigate hepatotoxicity of yttrium-90 resin microspheres radioembolization in patients who were previously treated with PRRT.

Methods

Patients treated with radioembolization after systemic radionuclide treatment were retrospectively analysed. Imaging response according to response evaluation criteria in solid tumours (RECIST) v1.1 and clinical response after 3 months were collected. Clinical, biochemical and haematological toxicities according to common terminology criteria for adverse events (CTCAE) v4.03 were also collected. Specifics on prior PRRT, subsequent radioembolization treatments, treatments after radioembolization and overall survival (OS) were collected.

Results

Forty-four patients were included, who underwent a total of 58 radioembolization procedures, of which 55% whole liver treatments, at a median of 353 days after prior PRRT. According to RECIST 1.1, an objective response rate of 16% and disease control rate of 91% were found after 3 months. Clinical response was seen in 65% (15/23) of symptomatic patients after 3 months. Within 3 months, clinical toxicities occurred in 26%. Biochemical and haematological toxicities CTCAE grade 3–4 occurred in ≤ 10%, apart from lymphocytopenia (42%). Radioembolization-related complications occurred in 5% and fatal radioembolization-induced liver disease in 2% (one patient). A median OS of 3.5 years [95% confidence interval 1.8–5.1 years] after radioembolization for the entire study population was found.

Conclusion

Radioembolization after systemic radionuclide treatments is safe, and the occurrence of radioembolization-induced liver disease is rare.

Level of Evidence

4, case series.

Percutaneous Laser Ablation of Liver Metastases from Neuroendocrine Neoplasm. A Retrospective Study for Safety and Effectiveness

PURPOSE

To retrospectively assess safety and efficacy of laser ablation (LA) of multiple liver metastases (LM) from neuroendocrine neoplasms (NEN).

METHODS

Twenty-one patients with NEN and at least 3 LM ≤ 4 cm in diameter underwent ultrasonography-guided LA. Up to seven LM were ablated in a single session; if the number of LM exceeded seven, the remaining LM were ablated in further LA sessions with a time interval of 3-4 weeks. LA was performed according to the multifiber technique. The patients underwent contrast-enhanced CT 1 month after LA, and were subsequently monitored every 3 months for the first 2 years and then every 6 months.

RESULTS

In total, 189 LM were treated in 21 patients (mean 9 ± 8.2, median 6) in 41 LA sessions (range 1-5). The diameter of LM ranged from 5 to 35 mm (median 19 mm, mean 17.9 ± 6.4 mm). One grade 4 complication occurred (0.53%): a bowel perforation managed by surgery. Technical efficacy was 100%, primary efficacy rate 94.7%, and secondary efficacy rate 100%. Complete relief of hormone-related symptoms was obtained in all the 13 symptomatic patients. Median follow-up was 39 months (range 12-99). 1-, 2-, 3-, and 5-year survival rates were 95%, 86%, 66%, and 40%, respectively. Overall survival resulted higher for patients with Ki-67 expression ≤ 7% than for those with Ki-67 > 7% (p = 0.0347).

CONCLUSIONS

LA is a promising and safe technique to treat LM from NEN. A longer follow-up should provide definitive information on the long-term efficacy of this liver-directed therapy.

LEVEL OF EVIDENCE

Retrospective study, local non-random sample, level 3.