Peptide receptor radionuclide therapy in the management of gastrointestinal neuroendocrine tumors: efficacy profile, safety, and quality of life

Optimising Radioligand Therapy for Patients with Gastro-Entero-Pancreatic Neuroendocrine Tumours: Expert Opinion from an Italian Multidisciplinary Group

Radioligand therapy (RLT) with lutetium (177Lu) oxodotreotide is an approved therapy in combination with somatostatin analogues (SSAs) for patients with advanced, well-differentiated G1-G2, gastro-entero-pancreatic neuroendocrine tumours (GEP-NETs) that progress on SSAs. We conducted a series of round table meetings throughout Italy to identify issues related to RLT delivery to patients with GEP-NETs. Four key issues were identified: (1) the proper definition of tumour progression prior to RLT initiation; (2) the impact of RLT in patients with bone metastases and/or high hepatic tumour burden; (3) the optimal follow-up protocol after RLT; and (4) organisational issues related to RLT use and managerial implications. This article reviews the literature relating to the aforementioned issues and makes recommendations based on available evidence and Italian NET experts' opinions. In particular, the group recommends the development of a diagnostic-therapeutic care pathway (DTCP) for patients undergoing RLT which provides systematic guidance but can still be individualised for each patient's clinical and psychosocial needs. A DTCP may clarify the diagnostic, therapeutic and post-treatment monitoring process, and improve communication and the coordination of care between hub and spoke centres. The DTCP may also contribute to changes in the care process related to the 2013/59/EURATOM Directive and to the definition of costs when planning for future or updated reimbursement of RLT in Italy.

Comparative evaluation of radionuclide therapy using 90Y and 177Lu

OBJECTIVE

Both ⁹⁰Y and ¹⁷⁷Lu are attractive β-emitters for radionuclide therapy and have been used in clinical practice. Nevertheless, comparative evaluation between ⁹⁰Y- and ¹⁷⁷Lu-labeled molecules has not been fully conducted. Thus, in this study, the features of ⁹⁰Y and ¹⁷⁷Lu for radionuclide therapy were assessed in tumor-bearing mice.

METHODS

Two tumor cell lines with different growth rates were used. Biodistribution studies of ¹⁷⁷Lu-labeled antibodies (¹⁷⁷Lu-Abs) were conducted in each tumor-bearing mouse model. Subsequently, the therapeutic effect of ⁹⁰Y- and ¹⁷⁷Lu-Ab were assessed in tumor-bearing mice. The absorbed radiation dose for the tumor was estimated using the Monte Carlo simulation.

RESULTS

¹⁷⁷Lu-Abs demonstrated high tumor accumulation in both tumor-xerograph. In the fast-growing tumor model, ⁹⁰Y-Ab showed a better therapeutic effect than ¹⁷⁷Lu-Ab, reflecting a higher absorbed radiation dose of ⁹⁰Y-Ab than that of ¹⁷⁷Lu-Ab. In the slow-growing tumor model, both ⁹⁰Y- and ¹⁷⁷Lu-Ab showed an excellent therapeutic effect; however, ¹⁷⁷Lu-Ab had a longer efficacy period than ⁹⁰Y-Ab, which could be attributed to the longer half-life and better dose uniformity of ¹⁷⁷Lu than those of ⁹⁰Y.

CONCLUSIONS

To accomplish a maximum therapeutic effect, selecting ⁹⁰Y or ¹⁷⁷Lu, to depend on the growth rate of individual cancer, would be helpful.

Association between fibrosis markers and kidney function following peptide receptor radionuclide therapy in patients with neuroendocrine tumours

Peptide receptor radionuclide therapy (PRRT) is a treatment for neuroendocrine tumours (NET). Renal impairment is a known side effect due to kidney fibrosis. We investigated the association between novel specific fibrosis markers and kidney function following PRRT. We included 38 patients who had all finished PRRT. In serum and urine, we analysed levels of three different fibrosis markers, PRO-C6 (type VI collagen formation), PRO-C3 (type III collagen formation) and C3M (type III collagen degradation). We determined kidney function by the ⁵¹Cr-EDTA plasma clearance. We used Wilcoxon rank sum test and Spearman's rank correlation to evaluate the association between the fibrosis markers and kidney function. We included 38 NET patients, 25 small-intestinal NET, 6 pancreatic NET, 2 pulmonary NET and 5 other types of NET. Median age was 69 years (IQR: 61-73). Median time from last PRRT to inclusion was 8 months (IQR: 3-20). We found significantly increased levels of serum PRO-C6 (p = .007) and urinary PRO-C6 (p = .033) and significantly decreased levels of urinary C3M (p = .035) in patients with impaired kidney function. Further, we observed a negative association between serum PRO-C6 and kidney function (rho = -0.33, p = .04) and a positive association between urinary C3M and kidney function (rho = 0.37, p = .02). We showed an association between the three fibrosis markers, serum PRO-C6, urinary PRO-C6 and urinary C3M and kidney function. These markers may help to improve the understanding of potential pathological tissue turnover and potentially improve monitoring of kidney function after PRRT in NET patients.

OUP accepted manuscript

Background

The aim of this study was to provide a guidance for the management of neuroendocrine tumors (NETs) in clinical practice.

Material and Methods

Nominal group and Delphi techniques were used. A steering committee of 8 experts reviewed the current management of NETs, identified controversies and gaps, critically analyzed the available evidence, and formulated several guiding statements for clinicians. Subsequently, a panel of 26 experts, was selected to test agreement with the statements through 2 Delphi rounds. Items were scored on a 4-point Likert scale from 1 = totally agree to 4 = totally disagree. The agreement was considered if ≥75% of answers pertained to Categories 1 and 2 (consensus with the agreement) or Categories 3 and 4 (consensus with the disagreement).

Results

Overall, 132 statements were proposed, which incorporated the following areas: (1) overarching principles; (2) progression and treatment response criteria; (3) advanced gastro-enteric NETs; (4) advanced pancreatic NETs; (5) advanced NETs in other locations; (6) re-treatment with radioligand therapy (RLT); (7) neoadjuvant therapy. After 2 Delphi rounds, only 4 statements lacked a clear consensus. RLT was not only recommended in the sequencing of different NETs but also as neoadjuvant treatment, while several indications for retreatment with RLT were also established.

Conclusion

This document sought to pull together the experts’ attitudes when dealing with different clinical scenarios of patients suffering from NETs, with RLT having a specific role where evidence-based data are limited.

Efficacy and safety of high-dose lanreotide autogel in patients with progressive pancreatic or midgut neuroendocrine tumours: CLARINET FORTE phase 2 study results

INTRODUCTION

This prospective, single-arm, phase 2 study assessed the efficacy and safety of lanreotide autogel (LAN) administered at a reduced dosing interval in patients with progressive neuroendocrine tumours (NETs) after LAN standard regimen.

METHODS

Patients had metastatic or locally advanced, grade 1 or 2 midgut NETs or pancreatic NETs (panNETs) and centrally assessed disease progression on LAN 120 mg every 28 days. They were treated with LAN 120 mg every 14 days for up to 96 weeks (midgut cohort) or 48 weeks (panNET cohort). The primary end-point was centrally assessed progression-free survival (PFS). PFS by Ki-67 categories was analysed post hoc. Secondary end-points included quality of life (QoL) and safety.

RESULTS

Ninety-nine patients were enrolled (midgut, N = 51; panNET, N = 48). Median (95% CI) PFS was 8.3 (5.6-11.1) and 5.6 (5.5-8.3) months, respectively. In patients with Ki-67 ≤ 10%, median (95% CI) PFS was 8.6 (5.6-13.8) and 8.0 (5.6-8.3) months in the midgut and panNET cohorts, respectively. Patients' QoL did not deteriorate during the study. There were no treatment-related serious adverse events and only two withdrawals for treatment-related adverse events (both in the panNET cohort).

CONCLUSIONS

In patients with progressive NETs following standard-regimen LAN, reducing the dosing interval to every 14 days provided encouraging PFS, particularly in patients with a Ki-67 ≤ 10% (post hoc); no safety concerns and no deterioration in QoL were observed. Increasing LAN dosing frequency could therefore be considered before escalation to less well-tolerated therapies.

An Impressive Approach in Nuclear Medicine: Theranostics

Radiometal-based theranostics or theragnostics, first used in the early 2000s, is the combined application of diagnostic and therapeutic agents that target the same molecule, and represents a considerable advancement in nuclear medicine. One of the promising fields related to theranostics is radioligand therapy. For instance, the concepts of targeting the prostate-specific membrane antigen (PSMA) for imaging and therapy in prostate cancer, or somatostatin receptor targeted imaging and therapy in neuroendocrine tumors (NETs) are part of the field of theranostics. Combining targeted imaging and therapy can improve prognostication, therapeutic decision-making, and monitoring of the therapy.

Automated and robust organ segmentation for 3D-based internal dose calculation

PURPOSE

In this work, we address image segmentation in the scope of dosimetry using deep learning and make three main contributions: (a) to extend and optimize the architecture of an existing convolutional neural network (CNN) in order to obtain a fast, robust and accurate computed tomography (CT)-based organ segmentation method for kidneys and livers; (b) to train the CNN with an inhomogeneous set of CT scans and validate the CNN for daily dosimetry; and (c) to evaluate dosimetry results obtained using automated organ segmentation in comparison with manual segmentation done by two independent experts.

METHODS

We adapted a performant deep learning approach using CT-images to delineate organ boundaries with sufficiently high accuracy and adequate processing time. The segmented organs were consequently used as binary masks for further convolution with a point spread function to retrieve the activity values from quantitatively reconstructed SPECT images for "volumetric"/3D dosimetry. The resulting activities were used to perform dosimetry calculations with the kidneys as source organs.

RESULTS

The computational expense of the algorithm was sufficient for clinical daily routine, required minimum pre-processing and performed with acceptable accuracy a Dice coefficient of [Formula: see text] for liver segmentation and of [Formula: see text] for kidney segmentation, respectively. In addition, kidney self-absorbed doses calculated using automated segmentation differed by [Formula: see text] from dosimetry performed by two medical physicists in 8 patients.

CONCLUSION

The proposed approach may accelerate volumetric dosimetry of kidneys in molecular radiotherapy with 177Lu-labelled radiopharmaceuticals such as 177Lu-DOTATOC. However, even though a fully automated segmentation methodology based on CT images accelerates organ segmentation and performs with high accuracy, it does not remove the need for supervision and corrections by experts, mostly due to misalignments in the co-registration between SPECT and CT images. Trial registration EudraCT, 2016-001897-13. Registered 26.04.2016, www.clinicaltrialsregister.eu/ctr-search/search?query=2016-001897-13 .

Combination radionuclide therapy: A new paradigm

Targeted molecular radionuclide therapy (MRT) has shown its potential for the treatment of cancers of multiple origins. A combination therapy strategy employing two or more distinct therapeutic approaches in cancer management is aimed at circumventing tumor resistance by simultaneously targeting compensatory signaling pathways or bypassing survival selection mutations acquired in response to individual monotherapies. Combination radionuclide therapy (CRT) is a newer application of the concept, utilizing a combination of radiolabeled molecular targeting agents with chemotherapy and beam radiation therapy for enhanced therapeutic index. Encouraging results are reported with chemotherapeutic agents in combination with radiolabeled targeting molecules for cancer therapy. With increasing awareness of the various survival and stress response pathways activated after radionuclide therapy, different holistic combinations of MRT agents with radiosensitizers targeting such pathways have also been explored. MRT has also been studied in combination with beam radiotherapy modalities such as external beam radiation therapy and carbon ion radiation therapy to enhance the anti-tumor response. Nanotechnology aids in CRT by bringing together multiple monotherapies on a single nanostructure platform for treating cancers in a more precise or personalized way. CRT will be a key player in managing cancers if correctly tailored to the individual patient profile. The success of CRT lies in an in-depth understanding of the radiobiological principles and pathways activated in response.

Update on Histological Reporting Changes in Neuroendocrine Neoplasms

PURPOSE OF REVIEW

Classification and nomenclature of neuroendocrine neoplasms (NEN) have frequently changed over the last years. These changes reflect both increasing knowledge and international standardisation.

RECENT FINDINGS

The most recent changes in the Gastro-Entero-Pancreatic system induced the concept of well-differentiated NET with high proliferation rate (NET G3), explaining partially the heterogeneity of G3 NEN. Even if the nomenclature in pulmonary NEN is still different, the terms 'carcinoid' and 'atypical carcinoid' are widely overlapping with NET G1 and NET G2. Molecular data shows an additional heterogeneity both in well-differentiated NET and poorly differentiated NEC. However, no studies are available demonstrating clinical usefulness yet. The heterogeneity of NEN regarding the organ of origin, differentiation and molecular subtypes make development of personalised therapy a challenge needing more international and interdisciplinary collaborations and clinical trials allowing stratification according to biological subgroups.

Clinical efficacy of first and second series of peptide receptor radionuclide therapy in patients with neuroendocrine neoplasm: a cohort study

OBJECTIVES

Peptide receptor radionuclide therapy (PRRT) is an established treatment for metastatic neuroendocrine neoplasms (NEN). However, only limited data exists for the effect of multiple series of PRRT. The aim of this study was to investigate PFS and OS inNEN patients treated with multiple series of PRRT conforming to the ENETS treatment protocol.

METHODS

We included all patients with gastrointestinal (GI), pancreatic and bronchopulmonary (BP) NEN treated with PRRT from 2008 to 2018. We used Kaplan-Meier estimation to evaluate PFS and OS with subgroup analysis of primary tumor, Ki67-index, type of radioisotope and number of PRRT series.

RESULTS

133 patients (female/male 61/72) were included, median age 70 (interquartile range 64-76) years. GI-NEN comprised 62%, pancreatic 23% and BP 11%. Median Ki67-index was 5%. After first PRRTG1- and G2-tumors had PFS of 25 and 22 months, compared to 11 months in G3-NENs (p < .05) and PFS was longer in G1/G2 GI-NENs than BP-NEN (30vs. 12 months, p < .05). After retreatment with a second series of PRRT, the overall PFS (G1-G3) was 19 months, with G1- and G2-tumors having the highest PFS of 19 and 22 months, respectively. Overall, the GI and BP tumors had an OS of 54 and 51 months.

CONCLUSIONS

PRRT is an effective therapy with long-term PFS and OS, especially in G1 and G2 NENs, and with better prognosis in GI-NEN compared with BP-NENs. OS and PFS was shorter after the second series of PRRT compared with the first, however results were still encouraging.

Radiopharmaceuticals for Neuroendocrine Tumors

Neuroendocrine tumors (NETs) are a heterogeneous group of tumors that originate in endocrine tissues throughout the body. Peptide receptor radionuclide therapy (PRRT) has emerged as a promising therapeutic option for patients with locally advanced and/or metastatic disease refractory to standard of care treatment. The landmark international phase III NETTER-1 trial led to the approval of ¹⁷⁷Lu-DOTATATE (Lutathera) in the treatment of somatostatin receptor-positive gastroenteropancreatic NETs. Similarly, data from the multicenter, phase II Study IB12B led to the approval of meta-[¹³¹I]Iodo-Benzyl-Guanidine (^I31I-MIBG) for treatment of iobenguane scan-positive, unresectable, locally advanced or metastatic pheochromocytoma or paraganglioma. With the clinical approval of these novel radiopharmaceuticals for managing select patients with NETs, additional studies are needed to refine patient selection, predict and assess therapy response, and optimize radiopharmaceutical delivery and clinical outcomes.

Comparative safety review of the current therapies for gastroenteropancreatic neuroendocrine tumors

Introduction: Neuroendocrine neoplasms (NENs) comprise a heterogeneous group of neoplasms, whose management requires complex and individualized clinical decisions. Over the last decades the advent of novel medications and advanced diagnostic and therapeutic modalities, alongside our deeper understanding of the disease, revolutionized the landscape of their management, significantly improving both prognosis and quality of life of patients.Area covered: Treatment-related adverse events and safety concerns as demonstrated in clinical trials, as well as in real-world clinical practice.Expert opinion: The only true curative option for NENs remains surgery, whereas high-grade advanced neuroendocrine carcinomas should be primarily managed with platinum-based chemotherapy. For the remaining cases, that comprise the vast majority, the current armamentarium includes somatostatin analogs, interferon, telotristat ethyl, molecular targeted therapies, chemotherapy, peptide receptor radionuclide therapy, and locoregional treatment. The use of the aforementioned therapeutic options is associated with several and not uncommonly severe treatment-related adverse events. However, the benefits offered inclusive of improved prognosis, amelioration of symptoms, and better quality of life amidst others, by far outweighs any adverse event.

Initial clinical evaluation of indigenous 90Y-DOTATATE in sequential duo-PRRT approach (177Lu-DOTATATE and 90Y-DOTATATE) in neuroendocrine tumors with large bulky disease: Observation on tolerability, 90Y-DOTATATE post- PRRT imaging characteristics (bremsstrahlung and PETCT) and early adverse effects

¹⁷⁷Lu-DOTATATE peptide receptor radionuclide therapy (PRRT) alone has lesser potential in the clinical setting of neuroendocrine tumor (NET) with large bulky disease and nonhomogeneous somatostatin receptors (SSTR) distribution, owing to lower energy (Eβmax 0.497 MeV) and a shorter particle penetration range (maximum 2–4 mm) of ¹⁷⁷Lu. In large bulky NETs, ⁹⁰Yttrium (⁹⁰Y) has the theoretical advantages because of a longer beta particle penetration range (a maximum soft tissue penetration of 11 mm). Therefore, a combination of ¹⁷⁷Lu and ⁹⁰Y is a theoretically sound concept that can result in better response in metastatic NET with large-bulky lesion and non-homogeneous SSTR distribution. The aim of the study was to determine the feasibility of combining ⁹⁰Y-DOTATATE with ¹⁷⁷Lu-DOTATATE PRRT as sequential duo-PRRT in metastatic NET with (≥5 cm) including the post ⁹⁰Y-DOTATATE-PRRT imaging and also to determine early toxicity of the duo-PRRT approach. A total of 9 patients received combination of ¹⁷⁷Lu-DOTATATE with ⁹⁰Y-DOTATATE (indigenously prepared and approved) through sequential duo-PRRT approach. These 9 NET patients were included and analyzed in this study. All 9 patients had undergone post-PRRT ⁹⁰Y-DOTATATE imaging, including a whole-body planar bremsstrahlung imaging followed by regional single-photon emission computed tomography (SPECT)-computed tomography (CT) imaging and also a regional positron emission tomography–computed tomography imaging. Grading of ⁹⁰Y-DOTATATE and ¹⁷⁷Lu-DOTATATE uptake was done on post-PRRT imaging by both modalities. The size of the lesions ranged from 5.5 cm to 16 cm with average size of 10 cm before sequential duo-PRRT was decided. Sequential duo-PRRT was administered because of stable, unresponsive disease following ¹⁷⁷Lu-DOTATATE in 5 patients (55.6%), progressive disease after ¹⁷⁷Lu-DOTATATE in 2 patients (22.2%), and with neoadjuvant intent in 2 patients (22.2%). The total cumulative dose of ¹⁷⁷Lu-DOTATATE before duo-pRRT ranged from 11.84 GBq to 37 GBq per patient and average administered dose of 27.21 GBq per patient in this study. Out of 9 patients, 8 patients received single cycle of ⁹⁰Y-DOTATATE (ranging from 2.66 GBq to 3.4 GBq per patient with average administered dose of 3.12 GBq per patient). One patient received two cycles of ⁹⁰Y-DOTATATE (total dose of 6.2 GBq). Out of 9 patients, 8 patients showed excellent tracer concentration in lesions on post-PRRT ⁹⁰Y-DOTATATE imaging and the remaining 1 patient showed fairly adequate ⁹⁰Y-DOTATATE tracer uptake in lesion on visual analysis. There was matched ⁹⁰Y-DOTATATE uptake with ⁶⁸Ga-DOTATATE and also with ¹⁷⁷LuDOTATATE in all 9 patients. The sequential duo-PRRT was well tolerated by all patients. Two patients (22.2%) developed mild nausea, one patient (11.1%) developed transient mild-grade hemoglobin toxicity, and one patient (11.1%) developed mild-grade gastrointestinal symptoms (loose motion and abdominal pain). No nephrotoxicity, hepatotoxicity, and other hematological toxicity was observed. The combination of the indigenous ⁹⁰Y-DOTATATE with ¹⁷⁷Lu-DOTATATE PRRT in NET as sequential duo-PRRT was well tolerated, feasible and safe in stable, unresponsive/progressive disease following single isotope ¹⁷⁷Lu-DOTATATE therapy and also in neoadjuvant PRRT setting with large bulky lesion (≥≥5cm). Post-PRRT ⁹⁰Y-DOTATATE imaging showed excellent ⁹⁰Y-DOTATATE uptake in nearly all NET patients. Mild-grade early adverse effects were easily manageable and controllable in this sequential duo-PRRT approach.

Preclinical PET Imaging of NTSR-1-Positive Tumors with 64Cu- and 68Ga-DOTA-Neurotensin Analogs and Therapy with an 225Ac-DOTA-Neurotensin Analog

Background: The aim of the study was to perform PET imaging and radiotherapy with a novel neurotensin derivative for neurotensin receptor 1 (NTSR-1)-positive tumors in an animal model. Materials and Methods: A di-DOTA analog of NT(6-13) with three unnatural amino acids was synthesized and radiolabeled with either ⁶⁴Cu or ⁶⁸Ga and tested for serum stability and tumor imaging in mice bearing NTSR-1-positive PC3, and HT29 xenografts. A dose-response therapy study was performed with 18.5, 37, and 74 kBq of ²²⁵Ac-di-DOTA-α,ɛ-Lys-NT(6-13). Results: ⁶⁸Ga-di-DOTA-α,ɛ-Lys-NT(6-13) was >99% stable in serum for 48 h, had an IC₅₀ of 5 nM using ¹²⁵I labeled NT(8-13) for binding to HT-29 cells, and high uptake in tumor models expressing NTSR-1. ⁶⁸Ga-di-DOTA-α,ɛ-Lys-NT(6-13) had an average %ID/g (n = 4) at 2 h of 4.0 for tumor, 0.5 for blood, 12.0 for kidney, and <1 for other tissues, resulting in a favorable T/B of 8. Mean survivals of tumor-bearing mice treated with 18.5 or 37 kBq of ²²⁵Ac-di-DOTA-α,ɛ-Lys-NT(6-13) were 81 and 93 d, respectively, versus 53 d for controls. Whole-body toxicity was seen for the 74 kBq dose. Conclusions: Based on the results of the animal model, di-DOTA-α,ɛ-Lys-NT(6-13) is a useful imaging agent for NTSR-1-positive tumors when radiolabeled with ⁶⁸Ga, and when radiolabeled with ²²⁵Ac, a potent therapeutic agent.

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.

The efficacy of 177Lu-DOTATATE peptide receptor radionuclide therapy (PRRT) in patients with metastatic neuroendocrine tumours: a systematic review and meta-analysis

PURPOSE

To evaluate the efficacy of ¹⁷⁷Lu-DOTA0-Tyr3-octreotate (¹⁷⁷Lu-DOTATATE) radionuclide therapy in patients with inoperable or metastatic neuroendocrine tumours (NETs), (PROSPERO ID CRD42019130755).

METHODS

All published clinical studies of NETs treated with ¹⁷⁷Lu-DOTATATE were identified based on systematic searches in the PubMed, EMBASE, Cochrane Library, Web of Science and ClinicalTrials.gov databases up to January 2019. Among these studies, only the reports evaluated with the "Response Evaluation Criteria in Solid Tumours (RECIST)" or "Southwest Oncology Group (SWOG)" criteria or both were included. We analysed the disease response rate (DRR) and disease control rate (DCR) of each group to evaluate the efficacy of ¹⁷⁷Lu-DOTATATE.

RESULTS

Fifteen studies were selected from 715 references. The pooled effect in the RECIST group (13 studies) was 27.58% (95% confidence interval (CI) 21.03-35.27%) for the DRR and 79.14% (95% CI 75.83-82.1%) for the DCR. In the SWOG criteria group (7 studies), the pooled effect was 20.59% (95% CI 10.89-35.51%) for the DRR and 78.28% (95% CI 74.39-81.72%) for the DCR. Therefore, the RECIST and SWOG groups showed similar DRRs and DCRs after¹⁷⁷Lu-DOTATATE treatment, indicating that ¹⁷⁷Lu-DOTATATE treatment has excellent efficacy with a control rate of approximately 78-79%. Moreover, adverse effects of ¹⁷⁷Lu-DOTATATE were minimal, including fatigue, nausea, vomiting and hormonal disorders.

CONCLUSIONS

For patients with inoperable or metastatic NETs, ¹⁷⁷Lu-DOTATATE is an effective treatment with minimal side effects.

Survival comparison between primary hepatic neuroendocrine neoplasms and primary pancreatic neuroendocrine neoplasms and the analysis on prognosis-related factors

BACKGROUND

Primary hepatic neuroendocrine neoplasms (PHNENs) are extremely rare and few articles have compared the prognosis of PHNENs with other neuroendocrine neoplasms (NENs). This study aimed to investigate the different prognosis between PHNENs and pancreatic NEN (PanNENs) and evaluate the relevant prognosis-related factors.

METHODS

From January 2012 to October 2016, a total of 44 NENs patients were enrolled and divided into two groups according to the primary tumor location which were named group PHNENs (liver; n = 12) and group PanNENs (pancreas; n = 32). Demographic, clinical characteristics and survival data were compared between the two groups with Kaplan-Meier method and log-rank tests. Prognostic factors were analyzed using the Cox regression model.

RESULTS

The overall survival of group PHNENs and group PanNENs were 25.4 ± 6.7 months and 39.8 ± 3.7 months, respectively (P = 0.037). The cumulative survival of group PanNENs was significantly higher than that of group PHNENs (P = 0.029). Univariate analysis revealed that sex, albumin, total bilirubin, total bile acid, aspartate aminotransferase, alkaline phosphatase, α-fetoprotein and carbohydrate antigen 19-9, histological types, treatments and primary tumor site were the prognostic factors. Further multivariate analysis indicated that albumin (P = 0.008), histological types NEC (P = 0.035) and treatments (P = 0.005) were the independent prognostic factors. Based on the histological types, the cumulative survival of patients with well-differentiated neuroendocrine tumor was significant higher than that of patients with poorly differentiated neuroendocrine carcinoma in group PHNENs (P = 0.022), but not in group PanNENs (P > 0.05). According to the different treatments, patients who received surgery had significantly higher cumulative survival than those with conservative treatment in both groups (P < 0.05).

CONCLUSIONS

PHNENs have lower survival compared to PanNENs. Histological types and treatments affect the prognosis. Surgical resection still remains the first line of treatment for resectable lesions and can significantly improve the survival.

Management of Gastrointestinal Neuroendocrine Tumors

Neuroendocrine neoplasms (NENs) are derived from neuroendocrine cell system and can have benign or malignant characteristics. They are rare tumors, but have been increasing in incidence over the past 40 years. Patients with NENs may develop symptoms due to primary tumor invasion, metastasis, or from secretion of hormonally active tumor substances. Multiple imaging modalities are used for diagnosis and staging, including specialty scans such as ¹¹¹In pentetreotide (Octreoscan) and ⁶⁸Gallium-DOTATATE, along with endoscopy, endoscopic ultrasound, and biochemical marker testing. Treatment involves both surgical approach, for both primary and metastatic lesions, as well as medical management for symptom management and disease progression. This article will review the current clinical knowledge regarding the diagnosis, treatment, and prognosis of these fascinating neoplasms and the associated hormonal syndromes.

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.

Detection and targeting insulin growth factor receptor type 2 (IGF2R) in osteosarcoma PDX in mouse models and in canine osteosarcoma tumors

Osteosarcoma (OS) represents 3.4% of all childhood cancers with overall survival of 70% not improving in 30 years. The consistent surface overexpression of insulin-like growth factor-2 receptor (IGF2R) has been reported in commercial and patient-derived xenograft (PDX) OS cell lines. We aimed to assess efficacy and safety of treating PDX and commercial OS tumors in mice with radiolabeled antibody to IGF2R and to investigate IGF2R expression on canine OS tumors. IGF2R expression on human commercial lines 143B and SaOS2 and PDX lines OS-17, OS-33 and OS-31 was evaluated by FACS. The biodistribution and microSPECT/CT imaging with 111Indium-2G11 mAb was performed in 143B and OS-17 tumor-bearing SCID mice and followed by radioimmunotherapy (RIT) with 177Lutetium-2G11 and safety evaluation. IGF2R expression in randomly selected canine OS tumors was measured by immunohistochemistry. All OS cell lines expressed IGF2R. Biodistribution and microSPECT/CT revealed selective uptake of 2G11 mAb in 143B and OS-17 xenografts. RIT significantly slowed down the growth of OS-17 and 143B tumors without local and systemic toxicity. Canine OS tumors expressed IGF2R. This study demonstrates the feasibility of targeting IGF2R on OS in PDX and spontaneous canine tumors and sets the stage for further development of RIT of OS using comparative oncology.

Quality of life in patients with midgut NET following peptide receptor radionuclide therapy

OBJECTIVES

There is convincing evidence that peptide receptor radionuclide therapy (PRRT) using ¹⁷⁷Lu-DOTATATE compared to octreotide therapy has a positive effect on overall survival and progression-free survival in midgut neuroendocrine tumors (NET). The current study analyzed health-related quality of life (QoL) in patients undergoing PRRT with a special focus on differences in functional performance.

MATERIALS AND METHODS

In our study, 70 patients (39 men or 31 female) suffering from midgut NET were included, with a mean age of 64.2 years. Functional performance was assessed by the index of the Eastern Cooperative of Oncology Group (ECOG). Thirty-three patients (47%) showed ECOG 0, 31 patients (44%) ECOG 1, and six patients (9%) ECOG 2. Health-related QoL was assessed by the EORTC QLQ-C30 questionnaire filled in at baseline and 3 months after each PRRT cycle.

RESULTS

The median cumulative administered activity was 27.4 GBq. Global health status significantly improved compared to baseline status after 1st (p = 0.05), 2nd (p = 0.004), and 3rd (p = 0.04) treatment cycle. Analyzing specific aspects of QoL, emotional functioning significantly improved after 1st and 2nd treatment cycle (both p < 0.001) as well as after 3rd cycle (p = 0.001). With regard to cognitive functioning, there was a significant improvement after 1st and 2nd treatment cycle (p = 0.003 and p = 0.05 respectively). With regard to alleviation of somatic symptoms, a significant reduction in pain and diarrhea was observed after the 2nd cycle (p = 0.038) and 3rd cycle (p = 0.036). Furthermore, changes in QoL in relation to functional performance status as assessed by ECOG were analyzed. There were no significant differences with regard to QoL alterations between patients with high (ECOG 0 or 1) and moderate performance status.

CONCLUSION

Our study confirmed an equally positive effect of PRRT on quality of life in midgut NET patients with high or moderate functional status in terms of increasing global health, functional status, and alleviating symptoms.

Peptide Receptor Radionuclide Therapy as a Novel Treatment for Metastatic and Invasive Phaeochromocytoma and Paraganglioma

At present there is no clinical guideline or standardised protocol for the treatment of metastatic or invasive phaeochromocytoma and paraganglioma (collectively known as PPGL) due to the rarity of the disease and the lack of prospective studies or extended national databases. Prognosis is mainly determined by genetic predisposition, tumour burden, rate of disease progression, and location of metastases. For patients with progressive or symptomatic disease that is not amenable to surgery, there are various palliative treatment options available. These include localised therapies including radiotherapy, radiofrequency, or cryoablation, as well as liver-directed therapies for those patients with hepatic metastases (e.g., transarterial chemoembolisation) and systemic therapies including chemotherapy or molecular targeted therapies. There is currently intense research interest in the value of radionuclide therapy for neuroendocrine tumours, including phaeochromocytoma and paraganglioma, with either iodine-131 (131I)-radiolabelled metaiodobenzylguanidine or very recently peptide receptor radionuclide therapy (PRRT), and the most important contemporary clinical studies will be highlighted in this review. The studies to date suggest that PRRT may induce major clinical, biochemical, and radiological changes, with 177Lu-DOTATATE being most efficacious and presenting less toxicity than 90Y-DOTATATE. Newer combination therapies with combined radioisotopes, or combinations with chemotherapeutic agents, also look promising. Given the favourable efficacy, logistic, and safety profiles, we believe that PRRT will probably become the standard treatment for inoperable metastatic PPGL in the near future, but we await data from definitive randomised controlled trials to understand its role.

A five-compartment biokinetic model for 90 Y-DOTATOC therapy

PURPOSE

Neuroendocrine tumors (NETs) are now routinely treated by radiopeptide targeted therapy using somatostatin receptor-binding peptides such as ⁹⁰ Y- and ¹⁷⁷ Lu-DOTATOC. The objective of this work was to develop a biokinetics model of ⁹⁰ Y labelled DOTATOC, which is applied in the therapy of NETs to estimate doses in kidney and tumor.

METHODS

A multi-compartment model described by two sets of differential equations, one set for the actual 30-min infusion and the other set for the post-infusion period was developed and activities were measured by liquid scintillation counting in blood (compartment 1) and the urine (compartment 3). The inter-compartment transfer coefficients, λ_ij , were varied to yield the best fit of the calculated to the measured time-activity data and the ⁹⁰ Y-DOTATOC time-activity data in the five-compartments comprising the human body were thus determined. The resulting time-activity curves were integrated over the interval from 0 to 72 h post administration to obtain the number of radioactive decays in each compartment and, in case of the kidneys and tumor, then multiplied by the self-dose ⁹⁰ Y beta particle absorbed fraction, determined by Monte Carlo (MC) simulation, the kidney and tumor absorbed doses.

RESULTS

Transfer coefficients λ_ij , were determined for five-compartments for all patients. Time- activity curves of ⁹⁰ Y-DOTATOC in 14 patients were determined, and two typical ones are shown graphically. Absorbed doses in the tumor and kidneys, obtained by the developed method, were determined. The mean absorbed dose in a kidney per unit of administered activity is 1.43 mGy/MBq (range 0.73-2.42 mGy/MBq). The tumor dose was determined as 30.94 mGy/MBq (range 20.05-42.31 mGy/MBq).

CONCLUSION

Analytical solution of a biokinetic model for ⁹⁰ Y-DOTATOC therapy enabled determination of the transfer coefficients and derivation of time-activity curves and kidney and tumor absorbed doses for 14 treated patients. The model can be applied to other radionuclides where elimination is predominantly through urine, which is often the case in radiopharmaceuticals.

The Role of Adding Somatostatin Analogues to Peptide Receptor Radionuclide Therapy as a Combination and Maintenance Therapy

Purpose: Although somatostatin analogues (SSA) and peptide receptor radionuclide therapy (PRRT) are validated therapies in patients with advanced gastroenteropancreatic neuroendocrine tumors (GEP-NET), it remains unclear whether SSA combined with PRRT or as maintenance therapy can provide prolonged survival compared with patients treated with PRRT alone. In this retrospective study, we aimed to investigate whether there is a survival benefit to adding SSA to PRRT as a combination therapy and/or maintenance therapy.Patients and Methods: The investigation included 168 patients with unresectable GEP-NETs treated at the University Hospital Bonn, Bonn, Germany. The patients were divided into two main groups: PRRT monotherapy (N = 81, group 1) and PRRT plus SSA (N = 87, group 2) as combined therapy with PRRT and/or as maintenance therapy after PRRT.Results: Data for overall survival (OS) were available from 168 patients, of whom 160 had data for progression-free survival (PFS). The median PFS was 27 months in group 1 versus 48 months in group 2 (P = 0.012). The median OS rates were 47 months in group 1 and 91 months in group 2 (P < 0.001). The death-event rates were lower in group 2 (26%) than in group 1 (63%). SSA as a combination therapy with PRRT and/or as a maintenance therapy showed a clinical benefit rate (objective response or stable disease) of 95%, which was significantly higher than group 1 (79%).Conclusions: SSA as a combination therapy and/or maintenance therapy may play a significant role in tumor control in patients with GEP-NET who underwent a PRRT. Clin Cancer Res; 24(19); 4672-9. ©2018 AACR.

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.

Practical management of toxicities associated with targeted therapies for advanced gastroenteropancreatic neuroendocrine tumors

Neuroendocrine tumors are heterogeneous, rare malignancies that arise most frequently in the gastroenteropancreatic tract (GEPNET). The therapeutic armamentarium for the treatment of GEPNETs has expanded significantly over the last two decades, however the ideal sequencing strategy remains controversial. As this disease may be relatively slow-growing, patients are expected to be treated for longer periods, so that even mild toxicities can influence quality of life, compliance and outcome in the long run. Prospective data on optimal adverse event management are lacking and recommendations are largely based on expert opinion and drug prescribing information. This review summarizes practical recommendations for toxicity management associated with the most commonly used GEPNET treatment options and stresses important focus points for future clinical trials.

Extremely Long Survival under Combined Immunotherapy in a Metastatic Functional Neuroendocrine Neoplasia Patient

Treatment and prognosis of neuroendocrine neoplasia depends on tumor size, stage, grade, resectability, and extent of distant metastasis. In most cases a multimodality approach including surgical, locally invasive procedures, peptide-guided radioreceptor therapy (PRRT), and medical therapies represent the mainstay of treatment in advanced disease. In the reported case, a 68-year-old man was diagnosed in 2010 with an initially functional (histamine) neuroendocrine tumor of gastric type III, G2, stage IVB, cT4cN1cM1 (hepatic, peritoneal, nodal, osseous), including a hepatic tumor load of 25%. Intensive multimodality approaches including combined immunotherapy (vaccination and PD-1/CTLA-4 blockade) led to a survival of 8 years until now with a high quality of life and minimal residual disease (only a single, small paragastric recurrence) despite the dedifferentiation of the tumor into a neuroendocrine carcinoma G3 (Ki-67 of 80%) including a nonfunctional stage.

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.