Phase II study of radiopeptide 177Lu-octreotate and capecitabine therapy of progressive disseminated neuroendocrine tumours

Advances in the Management of Medullary Thyroid Carcinoma: Focus on Peptide Receptor Radionuclide Therapy

Effective treatment options in advanced/progressive/metastatic medullary thyroid carcinoma (MTC) are currently limited. As in other neuroendocrine neoplasms (NENs), peptide receptor radionuclide therapy (PRRT) has been used as a therapeutic option in MTC. To date, however, there are no published reviews dealing with PRRT approaches. We performed an in-depth narrative review on the studies published in this field and collected information on registered clinical trials related to this topic. We identified 19 published studies, collectively involving more than 200 patients with MTC, and four registered clinical trials. Most cases of MTC were treated with PRRT with somatostatin analogues (SSAs) radiolabelled with 90 yttrium (90Y) and 177 lutetium (177Lu). These radiopharmaceuticals show efficacy in the treatment of patients with MTC, with a favourable radiological response (stable disease, partial response or complete response) in more than 60% of cases, coupled with low toxicity. As MTC specifically also expresses cholecystokinin receptors (CCK2Rs), PRRT with this target has also been tried, and some randomised trials are ongoing. Overall, PRRT seems to have an effective role and might be considered in the therapeutic strategy of advanced/progressive/metastatic MTC.

Medical Treatment of Gastrointestinal Neuroendocrine Neoplasms

Neuroendocrine neoplasms (NENs) are rare tumours that arise mainly in the gastrointestinal or pulmonary system. Most NENs are well-differentiated and may obtain prolonged survival besides the presence of metastatic disease; however, a subset (poorly differentiated NENs) may display a truly aggressive behaviour exhibiting a poor prognosis. The recently developed classification systems along with advances in functional imaging have helped stratify patients to the administration of appropriate therapeutic options. Surgery is the mainstay of treatment of NENs, but in recent decades there has been a considerable evolution of medical treatments that are used for locally advanced or metastatic disease not amenable to surgical resection. Long acting somatostatin analogues are the main therapeutic modality for patients with functioning and well-differentiated low grade NENs exhibiting symptomatic control and mainly stabilisation of tumour growth. Other systemic treatments include chemotherapy, molecular targeted agents, interferon-α, peptide receptor radionuclide therapy (PRRT), and immunotherapy. In addition, new agents such as telotristat may be used for the control of symptoms of carcinoid syndrome. The choice and/or sequence of therapeutic agents should be individualized according to tumour origin and differentiation, disease burden, presence of clinical symptoms and patients' performance status in the context of a multidisciplinary approach. Recent advances in the molecular pathogenesis of NENs set the field for a more personalised treatment approach.

Enhancing the anti-tumour activity of 177Lu-DOTA-octreotate radionuclide therapy in somatostatin receptor-2 expressing tumour models by targeting PARP

Peptide receptor radionuclide therapy (PRRT) is an important treatment option for patients with somatostatin receptor-2 (SSTR2)-expressing neuroendocrine tumour (NET) though tumour regression occurs in only a minority of patients. Therefore, novel PRRT regimens with improved therapeutic activity are needed. Radiation induced DNA damage repair is an attractive therapeutic target to increase PRRT efficacy and consequently, we have characterised a panel of preclinical models for their SSTR2 expression, in vivo growth properties and response to 177Lu-DOTA-octreotate (LuTate) PRRT to identify models with features suitable for evaluating novel therapeutic combinations. In vitro studies using the SSTR2 expressing AR42J model demonstrate that the combination of LuTate and the small molecule Poly(ADP-ribose) polymerase-1 (PARP) inhibitor, talazoparib led to increased DNA double strand breaks, as assessed by γ-H2AX foci formation, as compared to LuTate alone. Furthermore, using the AR42J tumour model in vivo we demonstrate that the combination of LuTate and talazoparib significantly improved the anti-tumour efficacy of LuTate alone. These findings support the clinical evaluation of the combination of LuTate and PARP inhibition in SSTR2-expressing NET.

177Lu-PRRT in advanced gastrointestinal neuroendocrine tumors: 10-year follow-up of the IRST phase II prospective study

PURPOSE

In March 2014, we reported the activity and safety of ¹⁷⁷Lu-DOTA-octreotate peptide receptor radionuclide therapy (Lu-PRRT) at two different dosages (18.5 GBq and 27.5 GBq in 5 cycles) in patients with progressive metastatic gastrointestinal neuroendocrine tumors (GI-NETs). Disease control rate (DCR) and toxicity were addressed. Herein, we report the late toxicity, progression-free survival (PFS), and overall survival (OS) in the same cohort after a 10-year follow-up.

METHODS

We conducted an open-label, disease-oriented prospective phase II trial. From March 2008 to June 2011, 43 patients received 3.7 GBq or 5.5 GBq of Lu-PRRT every 6 to 8 weeks, each cycle repeated 5 times. All patients showed ⁶⁸Gallium-DOTA-peptide PET/Octreoscan® positivity (score 3-4 Rotterdam scale) in known lesions. Tumor burden was estimated radiologically. Time-to-event data (PFS and OS) were described using Kaplan-Meier curves and compared with the log-rank test.

RESULTS

Forty-three patients (28 males and 15 females) were evaluable and were monitored for a median period of 118 months (range 12.6-139.6). Median PFS in patients receiving 18.5 GBq was 59.8 months (95% confidence interval [95% CI] 14.3-79.6), identical to that of patients treated with 27.5 GBq (59.8 months, 95% CI 23.4-82.0). Median OS was 71.0 months (95% CI 46.1-107.3) in the group who received 18.5 GBq and 97.6 months (95% CI 64.3-not reached) in the group treated with 27.5 GBq (P = 0.22). Patients with progression limited to lymph nodes showed significantly longer median PFS and OS than those with hepatic lesions (P = 0.02 for PFS and P = 0.04 for OS). Age over 65 years at the time of PRRT was also significant for OS. Of note, no late hematological or renal toxicity was observed in either group.

CONCLUSIONS

The long-term follow-up of the IRST phase II study shows that Lu-PRRT is a safe and effective therapy for patients with advanced GI-NET, the most important prognostic factor being tumor burden, hepatic lesions, and age. We believe that Lu-PRRT should be offered to patients with early-stage disease.

Targeted Systemic Treatment of Neuroendocrine Tumors: Current Options and Future Perspectives

Neuroendocrine tumors (NETs) originate from the neuroendocrine cell system in the bronchial and gastrointestinal tract and can produce hormones leading to distinct clinical syndromes. Systemic treatment of patients with unresectable NETs aims to control symptoms related to hormonal overproduction and tumor growth. In the last decades prognosis has improved as a result of increased detection of early stage disease and the introduction of somatostatin analogs (SSAs) as well as several new therapeutic options. SSAs are the first-line medical treatment of NETs and can control hormonal production and tumor growth. The development of next-generation multireceptor targeted and radiolabelled somatostatin analogs, as well as target-directed therapies (as second-line treatment options) further improve progression-free survival in NET patients. To date, however, a significant prolongation of overall survival with systemic treatment in NET has not been convincingly demonstrated. Several new medical options and treatment combinations will become available in the upcoming years, and although preliminary results of preclinical and clinical trials are encouraging, large, preferrably randomized clinical studies are required to provide definitive evidence of their effect on survival and symptom control.

Systemic treatment for lung carcinoids: from bench to bedside

In the huge spectrum of lung neuroendocrine neoplasms, typical and atypical carcinoids should be considered as a separate biological entity from poorly differentiated forms, harboring peculiar molecular alterations. Despite their indolent behavior, lung carcinoids correlate with a worse survival. To date, only limited therapeutic options are available and novel drugs are strongly needed. In this work, we extensively reviewed scientific literature exploring available therapeutic options, new molecular targets and future perspectives in the management of well differentiated neoplasms of bronchopulmonary tree. Systemic therapy represents the main option in advanced and unresectable disease; accepted choices are somatostatin analogs, peptide receptor radionuclide therapy, everolimus and chemotherapy. To date, an univocal treatment strategy has not been identified yet, thus tailored therapeutic algorithms should consider treatment efficacy as well as safety profiles. Several molecular alterations found in carcinoid tumors might act as molecular targets leading to development of new therapeutic options. Further studies are necessary to identify new potential “druggable” molecular targets in the selected subset of low-grade lung carcinoids. Furthermore, evaluating the available therapies in more homogeneous population might improve their efficacy through a perfect tailoring of treatment options.

Local treatment of liver metastases by administration of 177Lu-octreotate via isolated hepatic perfusion - A preclinical simulation of a novel treatment strategy

INTRODUCTION

Systemic ¹⁷⁷Lu-octreotate treatment for metastatic neuroendocrine tumours is restricted by organs at risk. By administering ¹⁷⁷Lu-octreotate during isolated hepatic perfusion (IHP), the uptake in organs at risk might be strongly reduced. The aim of this study was to investigate the feasibility to use the combination of IHP and radionuclide therapy.

METHODS

To simulate IHP, the liver of a pig was prepared for ex vivo perfusion. Blood containing 490 MBq ¹⁷⁷Lu-octreotate was circulated through the liver for 60 min, after which the liver was rinsed. After IHP, the liver was examined by SPECT/CT. Lastly, an intraoperative gamma detector (IGD) was used to determine ¹⁷⁷Lu activity concentration in the liver and results were compared with the activity concentration in corresponding liver biopsies.

RESULTS

Detector measurements over the liver during the IHP showed a fast increase with a maximum after approximately 10-15 min. After IHP, about 75% of the ¹⁷⁷Lu in the liver could be washed out. The SPECT/CT images revealed a relatively inhomogeneous distribution. Nevertheless, the IGD values of ¹⁷⁷Lu activity concentration showed acceptable agreement with the biopsy values.

CONCLUSIONS

Our results in pig show that it could be feasible to treat patients with liver metastases from NETs with ¹⁷⁷Lu-octreotate via IHP ¹⁷⁷. However, an inhomogeneous distribution of ¹⁷⁷Lu-octreotate in normal liver tissue is expected, and in order to determine the activity concentration with satisfactory accuracy using an IGD, measurements need to be performed at several positions over the liver.

Therapy With 177Lu-DOTATATE: Clinical Implementation and Impact on Care of Patients With Neuroendocrine Tumors

OBJECTIVE. The purpose of this article is to enhance knowledge of the clinical implementation of peptide receptor radionuclide therapy (PRRT) and its impact on care of patients with neuroendocrine tumors. CONCLUSION. Most well differentiated and some moderately and poorly differentiated neuroendocrine tumors express large numbers of somatostatin receptors on their cell surfaces. PRRT targets these cells with ¹⁷⁷Lu-DOTATATE, which is a medium-energy beta emitter. Since this agent received U.S. Food and Drug Administration approval in 2018, tremendous effort has been exerted at institutions throughout the United States toward proper implementation of this promising therapy. This review summarizes clinical implementation of PRRT and its impact on patient care.

Everolimus, lutetium-177 DOTATATE and sunitinib for advanced, unresectable or metastatic neuroendocrine tumours with disease progression: a systematic review and cost-effectiveness analysis

BACKGROUND

Neuroendocrine tumours (NETs) are a group of heterogeneous cancers that develop in cells in the diffuse neuroendocrine system.

OBJECTIVES

To estimate the clinical effectiveness of three interventions [everolimus (Afinitor^®; Novartis International AG, Basel, Switzerland), lutetium-177 DOTATATE (177Lu-DOTATATE) (Lutathera^®; Imaging Equipment Ltd, Radstock, UK) and sunitinib (Sutent^®; Pfizer Inc., New York, NY, USA)] for treating unresectable or metastatic NETs with disease progression and establish the cost-effectiveness of these interventions.

DATA SOURCES

The following databases were searched from inception to May 2016: MEDLINE, MEDLINE In-Process & Other Non-Indexed Citations, MEDLINE Daily, Epub Ahead of Print, EMBASE, Cochrane Central Register of Controlled Trials and Web of Science.

REVIEW METHODS

We systematically reviewed the clinical effectiveness and cost-effectiveness literature on everolimus, 177Lu-DOTATATE and sunitinib for treating advanced, unresectable or metastatic progressive NETs. The following NET locations were considered separately: pancreas, gastrointestinal (GI) tract and lung, and GI tract (midgut only). We wrote a survival partition cohort-based economic evaluation in Microsoft Excel^® 2013 (Microsoft Corporation, Redmond, WA, USA) from the UK NHS and Personal Social Services perspective. This comprised three health states: (1) progression-free survival (PFS), (2) progressed disease and (3) death.

RESULTS

Three randomised controlled trials (RCTs), RADIANT-3 [RAD001 in Advanced Neuroendocrine Tumors, Third Trial; pancreatic NETs (pNETs): everolimus vs. best supportive care (BSC)], A6181111 (pNETs: sunitinib vs. BSC) and RADIANT-4 (RAD001 in Advanced Neuroendocrine Tumors, Fourth Trial; GI and lung NETs: everolimus vs. BSC), met the inclusion criteria for the clinical effectiveness systematic review. The risk of bias was low. Although the NETTER-1 (Neuroendocrine Tumors Therapy) RCT, of 177Lu-DOTATATE plus 30 mg of octreotide (Sandostatin^®, Novartis) compared with 60 mg of octreotide, was excluded from the review, we nonetheless present the results of this trial, as it informs our estimate of the cost-effectiveness of 177Lu-DOTATATE. The pNETs trials consistently found that the interventions improved PFS and overall survival (OS) compared with BSC. Our indirect comparison found no significant difference in PFS between everolimus and sunitinib. Estimates of OS gain were confounded because of high rates of treatment switching. After adjustment, our indirect comparison suggested a lower, but non-significant, hazard of death for sunitinib compared with everolimus. In GI and lung NETs, everolimus significantly improved PFS compared with BSC and showed a non-significant trend towards improved OS compared with BSC. Adverse events were more commonly reported following treatment with targeted interventions than after treatment with BSC. In the base case for pNETs, assuming list prices, we estimated incremental cost-effectiveness ratios (ICERs) for everolimus compared with BSC of £45,493 per quality-adjusted life-year (QALY) and for sunitinib compared with BSC of £20,717 per QALY. These ICERs increased substantially without the adjustment for treatment switching. For GI and lung NETs, we estimated an ICER for everolimus compared with BSC of £44,557 per QALY. For GI (midgut) NETs, the ICERs were £199,233 per QALY for everolimus compared with BSC and £62,158 per QALY for a scenario analysis comparing 177Lu-DOTATATE with BSC. We judge that no treatment meets the National Institute for Health and Care Excellence's (NICE) end-of-life criteria, although we cannot rule out that sunitinib in the A6181111 trial does.

LIMITATIONS

A RCT with included comparators was not identified for 177Lu-DOTATATE. The indirect treatment comparison that our economic analysis was based on was of a simple Bucher type, unadjusted for any differences in the baseline characteristics across the two trials.

CONCLUSIONS

Given NICE's current stated range of £20,000-30,000 per QALY for the cost-effectiveness threshold, based on list prices, only sunitinib might be considered good value for money in England and Wales.

FUTURE WORK

Further analysis of individual patient data from RADIANT-3 would allow assessment of the robustness of our findings. The data were not made available to us by the company sponsoring the trial.

STUDY REGISTRATION

This study is registered as PROSPERO CRD42016041303.

FUNDING

The National Institute for Health Research Health Technology Assessment programme.

Preclinical Investigation of 212Pb-DOTAMTATE for Peptide Receptor Radionuclide Therapy in a Neuroendocrine Tumor Model

Somatostatin analogues have been examined as a treatment for somatostatin receptor overexpressing tumors for years; specifically, octreotate (TATE) and octreotide (TOC). Several versions of these analogues coupled to beta or gamma nuclides are currently used as imaging agents, as treatments with peptide receptor radionuclide therapy (PRRT) for patients with neuroendocrine tumors or are being explored in preclinical and clinical settings. Our study describes the use of ²¹²Pb-DOTAMTATE, the octreotate analogue, in combination with ²¹²Pb, the parent of an alpha emitter. Preclinical studies demonstrated tumor targeting of ²¹²Pb-DOTAMTATE of >20% ID/g up to 24 hours post drug injection. The addition of kidney protection agents, including l-lysine and l-arginine decreases drug accumulation in the kidneys and the addition of ascorbic acid to the chelation mixture reduces oxidation of the drug product. ²¹²Pb-DOTAMTATE displays a favorable toxicity profile with single-dose injections of 20 μCi showing 100% survival and with nontoxic cumulative doses up to 45 μCi, when fractionated into three smaller doses of 15 μCi. In an initial efficacy study, a single 10 μCi injection of ²¹²Pb-DOTAMTATE extended the mean survival 2.4-fold. Efficacy was enhanced by giving three treatment cycles of ²¹²Pb-DOTAMTATE and reducing the time between injections to two weeks. Efficacy was optimized further by the addition of a chemo-sensitizing agent, 5-fluorouracil, given in combination with three cycles of 10 μCi ²¹²Pb-DOTAMTATE. These conditions led to 79% of the animals being tumor free at the end of the 31-week study suggesting that ²¹²Pb-DOTAMTATE alone or in combination with a chemotherapeutic may have positive clinical implications.

Peptide Receptor Radionuclide Therapy for Patients With Advanced Lung Carcinoids

Neuroendocrine neoplasms (NEN) are a family of malignancies of diverse origin, including the lung, gastrointestinal tract, and pancreas. Lung NEN include well differentiated neuroendocrine tumors (NET) classified as typical carcinoids or atypical carcinoids, and poorly differentiated neuroendocrine carcinomas classified as small-cell lung carcinoma or large-cell neuroendocrine carcinoma. According to a recent analysis of a large, population-based registry, approximately one-third of all patients with lung typical/atypical carcinoids have distant metastases at diagnosis, and median survival for these patients is 24 months. At present, only 1 therapy is approved by the US Food and Drug Administration (FDA) for patients with advanced lung typical/atypical carcinoids, everolimus, indicating a clear need for more treatment options in this patient population. Although not yet supported by results from randomized prospective trials, somatostatin analogues are considered an acceptable treatment option for patients with lung typical/atypical carcinoids expressing somatostatin receptors. Peptide receptor radionuclide therapy (PRRT) with ¹⁷⁷Lu-DOTATATE was recently approved by the FDA for the treatment of gastroenteropancreatic NET; however, the role of PRRT in patients with lung typical/atypical carcinoids remains unclear, because they were not included in the pivotal NETTER-1 (Neuroendocrine Tumors Therapy) trial. Herein we provide a comprehensive review of the available clinical evidence for efficacy and safety of PRRT in patients with lung typical/atypical carcinoids. On the basis of the preliminary evidence of efficacy and the consistent safety profile in this patient group, we propose that experienced multidisciplinary NET teams may consider PRRT alongside everolimus as an option for patients with advanced somatostatin receptor-positive lung typical/atypical carcinoids whose disease is progressing during first-line treatment with somatostatin analogues.

Management of Primary Lymph Nodal Gastrinoma With Liver Metastases Resulting in Zollinger-Ellison Syndrome

Primary lymph node gastrinoma has been defined as gastrin-producing tumor present in lymph nodes and predominantly found in well-defined anatomical region known as gastrinoma triangle. They are usually localized preoperatively with imaging, and their surgical resection results in long-term relief. The authors report a case of unresectable primary lymph nodal gastrinoma with liver metastases in a 14-year-old adolescent boy with proven histopathology detected on Ga-DOTANOC whole-body PET/CT scan followed by preoperative multiple Lu-DOTATATE cycles for cytoreduction. Subsequent surgical resection of residual mass resulted in complete response with a follow-up of around 4 years in this unusual case of Zollinger-Ellison syndrome.

Current best practice in the management of neuroendocrine tumors

Neuroendocrine neoplasms are rare tumors that display marked heterogeneity with varying natural history, biological behavior, response to therapy and prognosis. Their management is complex, particularly as a number of them may be associated with a secretory syndrome and involve a variety of options. A number of factors such as proliferation rate, degree of differentiation, functionality and extent of the disease are mostly utilized to tailor treatment accordingly, ideally in the context of a multidisciplinary team. In addition, a number of relevant scientific societies have published therapeutic guidelines in an attempt to direct and promote evidence-based treatment. Surgery remains the treatment of choice with an intention to cure while it may also be recommended in some cases of metastatic disease and difficult to control secretory syndromes. Long-acting somatostatin analogs constitute the main treatment for the majority of functioning tumors, whereas specific evolving agents such as telotristat may be used for the control of carcinoid syndrome and related sequelae. In patients with advanced disease not amenable to surgical resection, treatment options include locoregional therapies, long-acting somatostatin analogs, molecular targeted agents, radionuclides, chemotherapy and recently immunotherapy, alone or in combination. However, the ideal time of treatment initiation, sequence of administration of different therapies and identification of robust prognostic markers to select the most appropriate treatment for each individual patient still need to be defined.

Feasibility and accuracy of single time point imaging for renal dosimetry following 177Lu-DOTATATE ('Lutate') therapy

Background

This study aims to assess both feasibility and accuracy of renal dosimetry imaging protocols in patients receiving Lutate therapy for neuroendocrine tumours (NETs), when data acquisition over multiple days is not possible on all cycles.

Method

Patients who had received a full 4 cycles of Lutate therapy with complete imaging at each cycle were included. Imaging consisted of quantitative SPECT/CT of the kidneys at 4, 24 and 96–120 h post injection. Renal absorbed dose was calculated for each data set, and in addition, five alternative methods were explored for comparison. Method 1: a patient average clearance time (t_1/2 average) derived from the first half of contributing patient data was used to estimate absorbed dose for subsequent patients based on 4 h imaging alone; method 2: t_1/2 average was applied to subsequent patients on 24 h imaging alone; method 3: a patient-specific clearance rate (t_1/2 patient) was determined from complete image data of cycle 1 and applied subsequently to remaining cycles using 4 h image data alone; method 4: t_1/2 patient was applied to 24 h imaging alone in subsequent cycles; method 5: the 120 h data was estimated on subsequent cycles based on the cycle 1 fraction of injected activity (%IA) at 24 and 120 h.

Results

Twenty treatments from 18 patients, resulting in 80 cycles of therapy, were analysed. The measured average renal absorbed dose per cycle of treatment was 0.38 ± 0.19 Gy/GBq when derived from full imaging data. The use of t_1/2 average applied to a single time point led to large deviations of dose estimates from true values (on average 59% and 30%, when using 4 h data and 24 h data, respectively). The use of complete image data on cycle 1 and the derivation of t_1/2 patient led to improved dose estimates, with an average deviation from true values of 13% and 2% when using 4 h data only and 24 h data only, respectively. The use of a 120 h %IA derived from cycle 1 led to an average deviation from true dose estimates of 14%.

Conclusion

In instances where demands on both patients and facilities make multiple time point data acquisition impractical, renal dosimetry is best derived through complete imaging at cycle 1 only followed by a single 24 h imaging time point on subsequent cycles, assuming no significant changes in renal function during the time course of therapy.

Theranostics in neuroendocrine tumours: somatostatin receptor imaging and therapy

Theranostics and its principles: pre-treatment selection of patients who are most likely to benefit from treatment by the use of a related, specific diagnostic test are integral to the treatment of patients with neuroendocrine tumours (NETs). This is due to NETs' important, but variable, somatostatin receptor (SSTR) expression, their heterogeneity and variation in site of primary and rate of progression. Only patients whose tumours have sufficient expression of SSTRs will benefit from SSTR-based radionuclide therapy and demonstrating this expression prior to therapy is essential. This article provides a relevant overview of NETs and the multiple facets of SSTR based theranostics, including imaging and therapy radionuclides; clinical efficacy and toxicity; patient selection and treatment and finally emerging radiopharmaceuticals and newer clinical applications.

Peptide Receptor Radiotherapy Comes of Age

Peptide receptor radionuclide therapy is a form of systemic radiotherapy shown to be effective in treating neuroendocrine tumors expressing somatostatin receptors. The NETTER-1 trial was the first randomized phase III clinical trial evaluating a radiolabeled somatostatin analog, and demonstrated significant improvement in progression-free survival among patients with midgut neuroendocrine tumors treated with ¹⁷⁷Lu-DOTATATE versus high-dose octreotide. This article discusses the evolution of peptide receptor radionuclide therapy, side effects, and potential future treatment approaches.

Correlation of dose with toxicity and tumour response to 90Y- and 177Lu-PRRT provides the basis for optimization through individualized treatment planning

PURPOSE

Peptide receptor radionuclide therapy (PRRT) with ⁹⁰Y-labelled and ¹⁷⁷Lu-labelled peptides is an effective strategy for the treatment of metastatic/nonresectable neuroendocrine tumours (NETs). Dosimetry provides important information useful for optimizing PRRT with individualized regimens to reduce toxicity and increase tumour responses. However, this strategy is not applied in routine clinical practice, despite the fact that several dosimetric studies have demonstrated significant dose-effect correlations for normal organ toxicity and tumour response that can better guide therapy planning. The present study reviews the key relationships and the radiobiological models available in the literature with the aim of providing evidence that optimization of PRRT is feasible through the implementation of dosimetry.

METHODS

The MEDLINE database was searched combining specific keywords. Original studies published in the English language reporting dose-effect outcomes in patients treated with PRRT were chosen.

RESULTS

Nine of 126 studies were selected from PubMed, and a further five were added manually, reporting on 590 patients. The studies were analysed and are discussed in terms of weak and strong elements of correlations.

CONCLUSION

Several studies provided evidence of clinical benefit from the implementation of dosimetry in PRRT, indicating the potential contribution of this approach to reducing severe toxicity and/or reducing undertreatment that commonly occurs. Prospective trials, possibly multicentre, with larger numbers of patients undergoing quantitative dosimetry and with standardized methodologies should be carried out to definitively provide robust predictive paradigms to establish effective tailored PRRT.

Large set data mining reveals overexpressed GPCRs in prostate and breast cancer: potential for active targeting with engineered anti-cancer nanomedicines

Over 800 G-protein-coupled receptors (GPCRs) are encoded by the human genome and many are overexpressed in tumors. GPCRs are triggered by ligand molecules outside the cell and activate internal signal transduction pathways driving cellular responses. The receptor signals are desensitized by receptor internalization and this mechanism can be exploited for the specific delivery of ligand-linked drug molecules directly into cells. Detailed expression analysis in cancer tissue can inform the design of GPCR-ligand decorated drug carriers for active tumor cell targeting. The active targeting process utilizes ligand receptor interactions leading to binding and in most cases internalization of the ligand-attached drug carrier resulting in effective targeting of cancer cells. In this report public microarray data from the Gene Expression Omnibus (GEO) repository was used to identify overexpressed GPCRs in prostate and breast cancer tissues. The analyzed data confirmed previously known cancer receptor associations and identified novel candidates for potential active targeting. Prioritization of the identified targeting receptors is also presented based on high expression levels and frequencies in cancer samples but low expression in healthy tissue. Finally, some selected examples were used in ligand docking studies to assess the feasibility for chemical conjugation to drug nanocarriers without interference of receptor binding and activation. The presented data demonstrate a large untapped potential to improve efficacy and safety of current and future anti-cancer compounds through active targeting of GPCRs on cancer cells.

Advanced neuroendocrine tumours of the small intestine and pancreas: clinical developments, controversies, and future strategies

In this Review, we discuss clinical developments and controversies in the treatment of neuroendocrine tumours (NETs) that are relevant for clinicians and clinical researchers. We describe advances in genetics, blood-based biomarkers, functional imaging, and systemic therapy of advanced NETs and discuss results of recent phase 3 studies, systemic treatment of advanced disease with peptide receptor radionuclide therapy, biotherapy, chemotherapy, and molecularly targeted therapy, and the potential role of immunotherapy in the treatment of NETs. Suggested treatment algorithms for NETs of ileal or jejunal origin and of pancreatic origin are presented.

Concomitant 177Lu-DOTATATE and Capecitabine Therapy in Patients With Advanced Neuroendocrine Tumors: A Long-term-Outcome, Toxicity, Survival, and Quality-of-Life Study

PURPOSE

The purpose of this study was to evaluate the outcome, toxicity, survival, and quality of life in patients with advanced neuroendocrine tumors.

METHODS

One hundred sixty-seven patients were enrolled in the study. All patients underwent baseline Ga-DOTANOC PET/CT scans. Lu-DOTATATE therapy was administered quarterly along with oral capecitabine therapy in group 1 patients (n = 88), whereas group 2 patients (n = 79) were treated only with Lu-DOTATATE. Hematologic, kidney function, liver function tests and chromogranin A levels were recorded before and after therapy at 2-week, 4-week, and 3-month intervals. Biochemical and morphological responses were assessed with the trend in chromogranin A levels and Response Evaluation Criteria in Solid Tumors 1.1 criteria, respectively.

RESULTS

There was no significant difference in the hemoglobin levels after Lu-DOTATATE therapy (P = 0.4892). In most patients, there was a decrease in the platelet levels; however, all the patients had platelet counts greater than 100,000/μL with no platelet toxicity. There was no toxicity related to leukocytes. Two patients showed renal insufficiencies. No hepatotoxicity was observed in any of the patients. According to Response Evaluation Criteria in Solid Tumors 1.1 criteria, in group 1 patients, the response was partial response in 34% of the patients, stable disease in 50.2%, and progressive disease in 6.8% versus partial response in 6.3%, stable disease in 60.9%, and progressive disease in 26.5% among group 2 patients. The median overall survival (OS) and progression-free survival (PFS) was not reached in group 1 patients. The median OS and PFS in group 2 patients were 48 months. Ki-67 tumor proliferation index was significantly associated with increased risk of disease progression.

CONCLUSIONS

Addition of capecitabine therapy with Lu-DOTATATE therapy lengthens the OS and PFS. Patients with aggressive disease may benefit from this synergetic therapeutic approach.

Recent advances in theranostics and challenges for the future

Theranostic nuclear oncology is on the cusp of adoption into routine clinical management of neuroendocrine tumours (NETs) following publication of the Phase 3 randomised controlled trial, NETTER-1. For the first time, level 1b evidence of efficacy and safety of 68-gallium/177-lutetium-DOTA-octreotate peptide receptor radionuclide therapy, of mid-gut neuroendocrine tumours was established. Multicentre Phase 2 studies of 68-gallium/177-lutetium-prostate specific membrane antigen theranostic approaches to management of end-stage metastatic castrate-resistant prostate cancer, are also very encouraging. However, the retrospective uncontrolled data currently available are inadmissible for formal regulatory agency evaluation. The challenge is to engage with oncologists and urologists, and to collaborate with the pharmaceutical industry, to design and perform the controlled clinical trials required for regulatory approval, and eventual reimbursement for theranostic nuclear oncology procedures. Strategies to facilitate timely establishment of an evidence base are considered in this review of theranostic advances over the past year. The prime objective is the provision of novel, effective, safe, personalised, tumour-targeted molecular theranostic management of metastatic castrate-resistant prostate cancer, and other cancers, such as non-Hodgkin lymphoma, which express the appropriate molecular receptor tumour targets. It would also be desirable to offer theranostic treatments at an earlier stage of malignant disease when the benefit is likely to be greater. The ultimate goal of theranostic nuclear oncology is to prolong survival and to improve quality of life for cancer patients worldwide. This may only be achieved through close collaboration between oncologists, nuclear physicians, radiologists, dosimetric physicists, Pharma, and, above all, with the patients themselves, in ways which are explored in this review.

Peptide Receptor Radionuclide Therapy and the Treatment of Gastroentero-pancreatic Neuroendocrine Tumors: Current Findings and Future Perspectives

Purpose and Methods

Patients with inoperable and metastasized neuroendocrine tumors (NETs), particularly those with grades 1 and 2, usually receive treatment with somatostatin analogues (SSAs). Peptide receptor radionuclide therapy (PRRT) has gained momentum over the past two decades in patients who progress on SSAs. 177Lu-DOTATATE is currently the most widely used radiopeptide for PRRT. We reviewed the recent evidence on PRRT and the treatment of gastroentero-pancreatic neuroendocrine tumors (GEP-NETs).

Results

¹⁷⁷Lu-DOTATATE can be used as neoadjuvant treatment in patients with inoperable GEP-NETs, who might be candidate for surgery after treatment and as adjuvant therapy after surgical intervention. Combination treatments of PRRT with chemotherapy or targeted agents as well as combinations of radionuclides in patients with NETs have been explored over the last few years. The majority of patients with NETs experience partial response or have disease stabilization, a small percentage has complete response, while some 30% of patients, however, will have disease progression. The safety and efficacy of retreatment with extra cycles of PRRT as salvage therapy have been evaluated in small retrospective series.

Conclusion

Overall, there is evidence that disease control and quality of life improve significantly after 117Lu PRRT therapy. Clinical trials on this therapy are scarce, and there is a need for further studies to establish proper management guidelines.

Review of Gallium-68 PSMA PET/CT Imaging in the Management of Prostate Cancer

Over 90% of prostate cancers over-express prostate specific membrane antigen (PSMA) and these tumor cells may be accurately targeted for diagnosis by 68Ga-PSMA-positron emission tomography/computed tomography (68Ga-PSMA-PET/CT) imaging. This novel molecular imaging modality appears clinically to have superseded CT, and appears superior to MR imaging, for the detection of metastatic disease. 68Ga-PSMA PET/CT has the ability to reliably stage prostate cancer at presentation and can help inform an optimal treatment approach. Novel diagnostic applications of 68Ga-PSMA PET/CT include guiding biopsy to improve sampling accuracy, and guiding surgery and radiotherapy. In addition to facilitating the management of metastatic castrate resistant prostate cancer (mCRPC), 68Ga-PSMA can select patients who may benefit from targeted systemic radionuclide therapy. 68Ga-PSMA is the diagnostic positron-emitting theranostic pair with the beta emitter Lutetium-177 PSMA (177Lu-PSMA) and alpha-emitter Actinium-225 PSMA (225Ac-PSMA) which can both be used to treat PSMA-avid metastases of prostate cancer in the molecular tumor-targeted approach of theranostic nuclear oncology.

Peptide Receptor Radionuclide Therapy With 177Lu-Octreotate in Patients With Somatostatin Receptor Expressing Neuroendocrine Tumors: Six Years' Assessment

OBJECTIVES

Peptide receptor radionuclide therapy (PRRT) with radiolabeled somatostatin analogues is a promising treatment for patients with inoperable, well to moderately differentiated metastatic neuroendocrine tumors (NETs). In continuation of our novel study with the radionuclide lutetium Lu, we now present further results of Lu DOTATATE therapy in managing NETs and other somatostatin receptor-expressing tumors in a larger and more diverse patient group.

PATIENTS AND METHODS

One hundred forty-four consecutive patients (85 men and 59 women; age range, 11-87 years; mean age, 58.5 years) with histologically confirmed NET were enrolled. One hundred forty-three patients received at least 1 cycle of treatment. Among them, 132 were deemed evaluable by having at least 1 cycle of treatment and a posttreatment MRI or CT scan for assessment based on modified Response Evaluation Criteria in Solid Tumors. Response to therapy was evaluated in terms of progression-free survival, overall survival, as well as radiologic, biochemical, and clinical responses. Further, analysis of symptoms was reviewed during therapy and also in subsequent follow-ups for safety evaluation. Renal, gastrointestinal (GI), hepatic, and hematological adverse events were evaluated using National Cancer Institute common toxicities criteria V4.03, through full blood panels, as well as consultation with patients for any symptoms and/or adverse events.

RESULTS

As of July 2016, median progression-free survival was about to be reached. Of 28 patients who have completed Lu DOTATATE therapy (completion of 4 or more cycles of treatment and all designated follow-ups), no patient showed complete response (CR), 8 patients (28.57%) showed partial response (PR), 16 patients (57.14%) showed stable disease (SD), and progressive disease (PD) was observed in 4 patients (14.28%). The objective response rate (CR + PR) of this group was 28.57% (n = 8) with a cumulative disease control (CR + PR + SD) of 85.71% (n = 24).Among 132 evaluable patients, assessment of treatment response using modified Response Evaluation Criteria in Solid Tumors criteria revealed CR in none of the patients, PR in 12 patients (9.09%), SD in 66 patients (50%), whereas PD, which included patients who passed away, was observed in 54 patients (40.90%), yielding an objective response rate of 9.09% (n = 12) and a cumulative disease control rate of 59.09% (n = 78).Symptoms including abdominal pain, diarrhea, flushing, and fatigue improved in over 50% of the patients, whereas weight loss improved in 28.26% of the patients. No grade 3 or grade 4 renal toxicities were found, though eleven grade 3 and five grade 4 hematological as well as three grade 3 hepatotoxicities were reported. Grade 3 hematotoxicity lasted an average of 2.7 months, and grade 4 lasted for only 0.9 months, whereas grade 3 hepatotoxicity lasted an average of 3.1 months.

CONCLUSIONS

Lu-octreotate peptide receptor radionuclide therapy has shown promising potential as a safe and effective targeted therapy in inoperable, well to moderately differentiated metastatic neuroendocrine cancers. The results of the multicenter randomized clinical trial conducted in United States and Europe are concordant with current study.

Theranostics of Neuroendocrine Tumors

Somatostatin receptor positron emission tomography/computed tomography using ⁶⁸Ga-labeled somatostatin analogs is the mainstay for the evaluation of receptor status in neuroendocrine tumors (NETs). This translates towards better therapy options, with increasing evidence of peptide receptor radionuclide therapy (PRRT) as the treatment of choice for advanced or progressive NETs. There are benefits in progression-free and overall survival as well as a significant improvement in clinical condition. In patients with progressive NETs, fractionated, personalized PRRT results in good therapeutic responses with no significant severe hematological and/or renal toxicity, thus improving quality of life.

Targeted Therapy for Medullary Thyroid Cancer: A Review

Medullary thyroid cancers (MTCs) constitute between 2 and 5% of all thyroid cancers. The 10-year overall survival (OS) rate of patients with localized disease is around 95% while that of patients with regional stage disease is about 75%. Only 20% of patients with distant metastases at diagnosis survive 10 years which is significantly lower than for differentiated thyroid cancers. Cases with regional metastases at presentation have high recurrence rates. Adjuvant external radiation confers local control but not improved OS. The management of residual, recurrent, or metastatic disease till a few years ago was re-surgery with local measures such as radiation. Chemotherapy was used with marginal benefit. The development of targeted therapy has brought in a major advantage in management of such patients. Two drugs—vandetanib and cabozantinib—have been approved for use in progressive or metastatic MTC. In addition, several drugs acting on other steps of the molecular pathway are being investigated with promising results. Targeted radionuclide therapy also provides an effective treatment option with good quality of life. This review covers the rationale of targeted therapy for MTC, present treatment options, drugs and methods under investigation, as well as an outline of the adverse effects and their management.

Molecular radiotheranostics for neuroendocrine tumours

This article discusses the important role of nuclear medicine imaging and therapy in the management of neuroendocrine tumours (NETs). Somatostatin receptor scintigraphy has a high impact on patient management versus conventional imaging. Molecular radiotherapy is an important part of the management of patients with NETs. Selection of patients for molecular radiotherapy in NETs is based on uptake on their radionuclide imaging study. The imaging agent has the same mechanism of uptake as the therapeutic agent. Thus, the imaging study preselects patients that are likely to concentrate radiation within their tumours.

Radionuclide Therapy for Neuroendocrine Tumors

Peptide receptor radionuclide therapy (PRRT) is a form of systemic radiotherapy that allows targeted delivery of radionuclides to tumor cells expressing high levels of somatostatin receptors. The two radiopeptides most commonly used for PRRT, ⁹⁰Y-DOTATOC and ¹⁷⁷Lu-DOTATATE, have been successfully employed for more than a decade for the treatment of advanced neuroendocrine tumors (NETs). Recently, the phase III, randomized NETTER-1 trial has compared ¹⁷⁷Lu-DOTATATE versus high-dose octreotide LAR in patients with progressive, metastatic midgut NETs, demonstrating exceptional tolerability and efficacy. This review summarizes recent developments in the field of radionuclide therapy for gastroenteropancreatic and lung NETs and considers possible strategies to further enhance its clinical efficacy.

Targeted radionuclide therapy in combined-modality regimens

Targeted radionuclide therapy (TRT) is a branch of cancer medicine concerned with the use of radioisotopes, radiolabelled molecules, nanoparticles, or microparticles that either naturally accumulate in or are designed to target tumours. TRT combines the specificity of molecular and sometimes physical targeting with the potent cytotoxicity of ionising radiation. Targeting vectors for TRT include antibodies, antibody fragments, proteins, peptides, and small molecules. The diversity of available carrier molecules, together with the large panel of suitable radioisotopes with unique physicochemical properties, allows vector-radionuclide pairings to be matched to the molecular, pathological, and physical characteristics of a tumour. Some pairings are designed for dual therapeutic and diagnostic applications. Use of TRT is increasing with the adoption into practice of radium-223 dichloride for the treatment of bone metastases and with the ongoing clinical development of, among others, 177Lu-dodecanetetraacetic acid tyrosine-3-octreotate (DOTATATE) for the treatment of neuroendocrine tumours and 90Y-microspheres for the treatment of hepatic tumours. The increasing use of TRT raises the question of how best to integrate TRT into multimodality protocols. Achievements in this area and the future prospects of TRT are evaluated in this Review.

Renal Function Assessment During Peptide Receptor Radionuclide Therapy

Theranostics labeled with Y-90 or Lu-177 are highly efficient therapeutic approaches for the systemic treatment of various cancers including neuroendocrine tumors and prostate cancer. Peptide receptor radionuclide therapy (PRRT) has been used for many years for metastatic or inoperable neuroendocrine tumors. However, renal and hematopoietic toxicities are the major limitations for this therapeutic approach. Kidneys have been considered as the "critical organ" because of the predominant glomerular filtration, tubular reabsorption by the proximal tubules, and interstitial retention of the tracers. Severe nephrotoxity, which has been classified as grade 4-5 based on the "Common Terminology Criteria on Adverse Events," was reported in the range from 0%-14%. There are several risk factors for renal toxicity; patient-related risk factors include older age, preexisting renal disease, hypertension, diabetes mellitus, previous nephrotoxic chemotherapy, metastatic lesions close to renal parenchyma, and single kidney. There are also treatment-related issues, such as choice of radionuclide, cumulative radiation dose to kidneys, renal radiation dose per cycle, activity administered, number of cycles, and time interval between cycles. In the literature, nephrotoxicity caused by PRRT was documented using different criteria and renal function tests, from serum creatinine level to more accurate and sophisticated methods. Generally, serum creatinine level was used as a measure of kidney function. Glomerular filtration rate (GFR) estimation based on serum creatinine was preferred by several authors. Most commonly used formulas for estimation of GFR are "Modifications of Diet in Renal Disease" (MDRD) equation and "Cockcroft-Gault" formulas. However, more precise methods than creatinine or creatinine clearance are recommended to assess renal function, such as GFR measurements using Tc-99m-diethylenetriaminepentaacetic acid (DTPA), Cr-51-ethylenediaminetetraacetic acid (EDTA), or measurement of Tc-99m-MAG3 clearance, particularly in patients with preexisting risk factors for long-term nephrotoxicity. Proximal tubular reabsorption and interstitial retention of tracers result in excessive renal irradiation. Coinfusion of positively charged amino acids, such as l-lysine and l-arginine, is recommended to decrease the renal retention of the tracers by inhibiting the proximal tubular reabsorption. Furthermore, nephrotoxicity may be reduced by dose fractionation. Patient-specific dosimetric studies showed that renal biological effective dose of <0Gy was safe for patients without any risk factors. A renal threshold value <28Gy was recommended for patients with risk factors. Despite kidney protection, renal function impairment can occur after PRRT, especially in patients with risk factors and high single or cumulative renal absorbed dose. Therefore, patient-specific dosimetry may be helpful in minimizing the renal absorbed dose while maximizing the tumor dose. In addition, close and accurate renal function monitoring using more precise methods, rather than plasma creatinine levels, is essential to diagnose the early renal functional changes and to follow-up the renal function during the treatment.

New therapeutic approaches to metastatic gastroenteropancreatic neuroendocrine tumors: A glimpse into the future

Neuroendocrine (NE) gastroenteropancreatic tumors are a heterogeneous group of neoplasias arising from neuroendocrine cells of the embryological gut. Their incidence have increased significantly over the past 3 decades probably due to the improvements in imaging and diagnosis. The recent advances in molecular biology have translated into an expansion of therapeutic approaches to these patients. Somatostatin analogs, which initially were approved for control of hormonal syndromes, have recently been proven to inhibit tumor growth. Several new drugs such as antiangiogenics and others targeting mammalian target of rapamycin pathways have been approved to treat progressive pancreatic neuroendocrine tumors (NETs) although their role in non-pancreatic is still controversial. The treatment of NETs requires a coordinated multidisciplinary approach. The management of localized NETs primarily involves surgical resection followed by surveillance. However, the treatment of unresectable and/or metastatic disease may involve a combination of surgical resection, systemic therapy, and liver-directed therapies with the goal of alleviating symptoms of peptide release and controlling tumor growth. This article will review the current therapeutic strategies for metastatic gastroenteropancreatic NETs and will take a glimpse into the future approaches.

Evaluation of two intraoperative gamma detectors for assessment of 177Lu activity concentration in vivo

BACKGROUND

Patients with somatostatin receptor-expressing neuroendocrine tumours can be treated with intravenously administered ¹⁷⁷Lu-octreotate. Few patients are cured with the present protocol due to the current dose limitation of normal organs at risk, such as the kidneys. By locally administering ¹⁷⁷Lu-octreotate to the liver for the purpose of treating liver metastases, a substantially reduced absorbed dose to organs at risk could be achieved. The development of such a technique requires the capability of measuring the ¹⁷⁷Lu activity concentration in tissues in vivo. The aim of this study was to evaluate different performance parameters of two commercially available intraoperative gamma detectors in order to investigate whether intraoperative gamma detector measurements could be used to determine ¹⁷⁷Lu activity concentration in vivo.

RESULTS

Measurements were made using different sources containing ¹⁷⁷Lu. Response linearity, sensitivity, spatial resolution and its depth dependence, organ thickness dependence of the measured count rate and tumour detectability were assessed for two intraoperative gamma detectors. The two detectors (a scintillation and a semiconductor detector) showed differences in technical performance. For example, the sensitivity was higher for the scintillation detector, while the spatial resolution was better for the semiconductor detector. Regarding organ thickness dependence and tumour detectability, similar results were obtained for both detectors, and even relatively small simulated tumours of low tumour-to-background activity concentration ratios could be detected.

CONCLUSIONS

Acceptable results were obtained for both detectors, although the semiconductor detector proved more advantageous for our purpose. The measurements demonstrated factors that must be corrected for, such as organ thickness or dead-time effects. Altogether, intraoperative gamma detector measurements could be used to determine ¹⁷⁷Lu activity concentration in vivo.

Clinical and Preclinical Advances in Gastroenteropancreatic Neuroendocrine Tumor Therapy

The molecular events leading to gastroenteropancreatic neuroendocrine tumor (GEP-NET) formation are largely unknown. Over the past decades, systemic chemotherapies have been replaced by therapies directed at particular molecular targets such as the somatostatin receptors, mTOR complexes or proangiogenic molecules. These approaches have demonstrated some success in subtypes of this heterogeneous tumor group, but responses are still widely varied. This review highlights the clinical trials ongoing for neuroendocrine tumors (NETs) and includes emerging immunotherapy, which holds great promise for NETs based on successes in other tumor types. Current avenues of preclinical research, including Notch and PI3K/AKT, will lead to additional targeted therapies based on genome-wide studies that have cast a wide net in the search for driver mutations. Future preclinical and clinical investigations are required to identify those mutations predictive of therapeutic response or disease progression. Results of current clinical trials outlined here will better inform patient management with respect to agent selection, timing, duration and combination therapy in the treatment of NETs.

ENETS Consensus Guidelines for the Standards of Care in Neuroendocrine Neoplasia: Peptide Receptor Radionuclide Therapy with Radiolabeled Somatostatin Analogues

The purpose of these guidelines is to assist physicians caring for patients with neuroendocrine neoplasia in considering eligibility criteria for peptide receptor radionuclide therapy (PRRT) and in defining the minimum requirements for PRRT. It is not these guidelines' aim to give recommendations on the use of specific radiolabelled somatostatin analogues for PRRT as different analogues are being used, and their availability is governed by varying international regulations. However, a recent randomized controlled trial, NETTER-1, has provided evidence that may establish ¹⁷⁷Lu-DOTA-octreotate (LutaThera®) as the first widely approved agent. It also makes recommendations on what minimal patient, tumour, and treatment outcome characteristics should be reported for PRRT to facilitate robust comparisons between studies.

Radionuclides in oncology clinical practice – review of the literature

Radionuclide therapy is a promising type of targeted therapy for cancer and its use is becoming more common in several types of malignant tumors.

Radiolabeled Somatostatin Analogue Therapy Of Gastroenteropancreatic Cancer

Peptide receptor radionuclide therapy (PRRT) has been utilized for more than two decades and has been accepted as an effective therapeutic modality in the treatment of inoperable or metastatic gastroenteropancreatic neuroendocrine neoplasms (NENs) or neuroendocrine tumors (NETs). The two most commonly used radiopeptides for PRRT, (90)Y-octreotide and (177)Lu-octreotate, produce disease-control rates of 68%-94%, with progression-free survival rates that compare favorably with chemotherapy, somatostatin analogues, and newer targeted therapies. In addition, biochemical and symptomatic responses are commonly observed. In general, PRRT is well tolerated with only low to moderate toxicity in most individuals. In line with the need to place PRRT in the therapeutic sequence of gastroenteropancreatic NENs, a recently sponsored phase III randomized trial in small intestine NENs treated with (177)Lu-octreotate vs high-dose octreotide long-acting release demonstrated that (177)Lu-octreotate significantly improved progression-free survival. Other strategies that are presently being developed include combinations with targeted therapies or chemotherapy, intra-arterial PRRT, and salvage treatments. Sophisticated molecular tools need to be incorporated into the management strategy to more effectively define therapeutic efficacy and for an early identification of adverse events. The strategy of randomized controlled trials is a key issue to standardize the treatment and establish the position of PRRT in the therapeutic algorithm of NENs.

Long-term follow-up and role of FDG PET in advanced pancreatic neuroendocrine patients treated with 177Lu-D OTATATE

PURPOSE

Lu-DOTATATE (Lu-PRRT) is a valid therapeutic option in differentiated pancreatic neuroendocrine tumors (P-NETs). FDG PET seems to be an important prognostic factor in P-NETs. We evaluated the efficacy of Lu-PRRT and the role of FDG PET in 60 patients with advanced P-NETs.

METHODS

From March 2008 to June 2011, 60 consecutive patients with P-NETs were enrolled in the study. Follow-up lasted until March 2016. Eligible patients were treated with two different total cumulative activities (18.5 or 27.8 GBq in 5 cycles every 6-8 weeks), according to kidney and bone marrow parameters.

RESULTS

Twenty-eight patients received a mean full activity (FA) of 25.9 GBq and 32 a mean reduced activity (RA) of 18.5 GBq. The disease control rate (DCR), defined as the sum of CR+PR+SD was 85.7 % in the FA group and 78.1 % in the RA group. Median progression-free survival (mPFS) was 53.4 months in the FA group and 21.7 months in the RA group (P = 0.353). Median overall survival (mOS) was not reached (nr) in FA patients and was 63.8 months in the RA group (P = 0.007). Fifty-five patients underwent an FDG PET scan before Lu-PRRT, 32 (58 %) showing an increased FDG uptake in tumor sites. mPFS was 21.1 months in FDG PET-positive patients and 68.7 months in the FDG PET-negative group (P < 0.0002), regardless of the total activity administered.

CONCLUSION

Both FA and RA are active in patients undergoing Lu-PRRT. However, an FA of 27.8 GBq of Lu-PRRT prolongs PFS and OS compared to an RA of 18.5 GBq. Our results indicate that FDG PET is an independent prognostic factor in this patient setting.

Peptide Receptor Radionuclide Therapy in the Treatment of Neuroendocrine Tumors

Peptide receptor radionuclide therapy (PRRT) is a promising new treatment modality for inoperable or metastasized gastroenteropancreatic neuroendocrine tumors patients. Most studies report objective response rates in 15% to 35% of patients. Progression-free (PFS) and overall survival (OS) compare favorably with that for somatostatin analogues, chemotherapy, or newer, "targeted" therapies. Prospective, randomized data regarding the potential PFS and OS benefit of PRRT compared with standard therapies is anticipated.

Systematic review reveals lack of quality in reporting health-related quality of life in patients with gastroenteropancreatic neuroendocrine tumours

BACKGROUND

Gastroenteropancreatic neuroendocrine tumours (GEP-NET) are often slow-growing and patients may live for years with metastasised disease. Hence, along with increasing overall and progression-free survival, treatments aim at preserving patients' well-being and health-related quality of life (HRQoL). However, studies on systematic HRQoL assessment in patients with GEP-NET are scarce. Therefore, the purpose of the current review is to systematically evaluate the methodological quality of the identified studies.

METHODS

A targeted database search was performed in PubMed, EMBASE, and CENTRAL. Data extraction was conducted by two independent researchers according to predefined criteria. For study evaluation, the Minimum Standard Checklist for Evaluating HRQoL Outcomes in Cancer Clinical Trials and the CONSORT Patient-Reported Outcome extension were adapted.

RESULTS

The database search yielded 48 eligible studies. We found the awareness for the need of HRQoL measurement to be growing and application of cancer-specific instruments gaining acceptance. Overall, studies were too heterogeneous in terms of patient characteristics and treatment interventions to draw clear conclusions for clinical practice. More importantly, a range of methodological shortcomings has been identified which were mainly related to the assessment and statistical analysis, as well as the reporting and interpretation of HRQoL data.

CONCLUSION

Despite an increasing interest in HRQoL in GEP-NET patients, there is still a lack of knowledge on this issue. A transfer of HRQoL results into clinical practice is hindered not only by the scarceness of studies, but also by the often limited quality of HRQoL processing and reporting.

Nephroprotective effects of enalapril after [177Lu]-DOTATATE therapy using serial renal scintigraphies in a murine model of radiation-induced nephropathy

Background

Radiation-induced nephropathy is still dose limiting in radionuclide therapy of neuroendocrine tumors. We investigated the nephroprotective potential of the angiotensine converting enzyme inhibiting drug enalpril after [177Lu]-DOTATATE therapy in a murine model of radiation-induced nephropathy by renal scintigraphy.

At first, the appropriate therapy activity to induce nephropathy was identified. Baseline scintigraphy (n = 12) entailed 12-min dynamic acquisitions after injection of 25 MBq [99mTc]-MAG3, which was followed by radionuclide therapy at four escalating activities of [177Lu]-DOTATATE: group (Gp) 1: 10 MBq; Gp 2: 20 MBq; Gp 3: 40 MBq; Gp 4: 65 MBq. Follow-up [99mTc]-MAG3 scintigraphy was carried out at days 9, 23, 44, and 65. The treatment activity for the intervention arm was selected on the basis of histological examination and declining renal function. In the second part, daily administration by gavage of 10 mg/kg/d enalapril or water (control group) was initiated on the day of radionuclide therapy. Follow-up scintigraphy was carried out at days 9, 23, 44, 65, and 86. We also created a non-therapy control group to detect therapy-independent changes of renal function over time. For all scintigraphies, mean renogram curves were analyzed and the “fractional uptake rate” (FUR; %I.D./min ± SEM) of the tracer by the kidneys was calculated as an index of renal clearance.

Results

At day 65 of follow-up, no significant change in the FUR relative to baseline (11.0 ± 0.3) was evident in radionuclide therapy groups 1 (11.2 ± 0.5) and 2 (10.1 ± 0.6), but FUR was significantly reduced in groups 3 (8.93 ± 0.6, p < 0.05) and 4 (6.0 ± 0.8, p < 0.01); we chose 40 MBq [177Lu]-DOTATATE (Gp 3) for the intervention study. Here, at the last day of follow-up (day 86), FUR was unaltered in enalapril-treated mice (11.8 ± 0.5) relative to the baseline group (12.4 ± 0.3) and non-therapy group (11.9 ± 0.8), whereas FUR in the control group had undergone a significant decline (9.3 ± 0.5; p < 0.01). Histological examination revealed prevention of kidney damage by enalapril treatment.

Conclusions

Treatment with enalapril is effective for nephroprotection during radionuclide therapy with [177Lu]-DOTATATE in mice. Although these results are only limitedly transferable to human studies, enalapril might serve as a promising drug in the mitigation of nephropathy following treatment with [177Lu]-DOTATATE.

Electronic supplementary material

The online version of this article (doi:10.1186/s13550-016-0219-2) contains supplementary material, which is available to authorized users.