Surgical Feasibility, Determinants, and Overall Efficacy of Neoadjuvant 177Lu-DOTATATE PRRT for Locally Advanced Unresectable Gastroenteropancreatic Neuroendocrine Tumors

Clinical application of targeted α-emitter therapy in gastroenteropancreatic neuroendocrine neoplasms

Effective therapeutic strategies for advanced gastroenteropancreatic neuroendocrine neoplasms (GEP-NENs) remain challenging, including a lack of response to therapy and post-treatment relapse. The rapid development of targeted radionuclide therapy (TRT) offers promising data for patients with somatostatin receptor (SSTR)-expressing tumors. This approach exhibits more advantages than somatostatin analog (SSA) therapy, which is primarily effective for well-differentiated and slow-growing GEP-NENs. Fortunately, some clinical studies on peptide receptor radionuclide therapy (PRRT) labeled with α-emitting radionuclides for GEP-NENs patients showed effective results for those with more advanced GEP-NENs, or those with malignant metastasis. For the improvement of clinical efficacy and the decline in the incidence of treatment-related relapse, recent progress in developing novel techniques and effective disease management strategies for optimal targeting has led to the emergence of targeted alpha therapy (TAT) in GEP-NENs patients. For instance, labeled technology and combination therapy could contribute to significantly improved long-term outcomes. However, the exact dosimetry for precision oncology, the shortage of radionuclides, and the stability of disease control are still under careful consideration. More high-quality, large-scale prospective studies are essential for obtaining valuable evidence on challenging problems and for further exploration.

Evaluation of the Real-Life Efficacy and Safety of the Treatment with Lutetium-177 Dotatate for Metastatic Neuroendocrine Tumors

Background: Therapy using lutetium-177 dotatate (177LU) was approved in Europe for the treatment of advanced neuroendocrine tumors (NETs) in 2017. Since then, it has become part of the strategies in the treatment of NETs, making it now possible to evaluate real-life results. Research Design and Methods: Single-arm, retrospective, multicenter, cohort study of all the patients with metastatic NETs treated with 177LU (four cycles of 200 mCi every 8 weeks) in the two medical centers dedicated to the treatment of NETs from the region of Aragón, Spain, from 2017 to 2024. Descriptive analysis of demographic characteristics, efficacy, and survival analysis were performed using the statistics software Jamovi 2.6.14. Results: Sixty-eight patients were included. The majority were male, and the most frequent primary location was the pancreas. The ORR was 30.9%. The DCR was 88%. The median OS was 47.4 months [95% CI, 25.6-NE]. The median PFS was 26.1 months [95% CI, 18.5-68.3]. High-grade tumors, multiple previous treatments, and pancreatic location presented worse OS. In total, 42.6% presented any grade adverse event (17.2% hematologic, 30.9% GI symptoms). Conclusions: The efficacy of 177LU in our study is like that observed in similar studies. Acceptable tolerance has been shown. Pancreatic tumors, previous treatments, and higher grades demonstrated worse outcomes. The new research line must consider the use of treatment with 177LU in earlier lines for metastatic disease as well as its possible use in local or locally advanced disease.

Role of neoadjuvant peptide receptor radionuclide therapy in unresectable and metastatic gastro-entero-pancreatic neuroendocrine neoplasms: A scoping review

Peptide receptor radionuclide therapy (PRRT) is an established therapy for metastatic neuroendocrine neoplasms (NEN). The role of PRRT as a neoadjuvant treatment prior to surgery or other local therapies is uncertain. This scoping review aimed to define the landscape of evidence available detailing the utility of PRRT in the neo-adjuvant setting, including the clinical contexts, efficacy, and levels of evidence. A comprehensive literature search of PUBMED, SCOPUS, and EMBASE through to December 2022 was performed to identify reports of PRRT use as neoadjuvant therapy prior to local therapies. Observational studies and clinical trials were included. A total of 369 records were identified by the initial search, and 17 were included in the final analysis, comprising 179 patients treated with neoadjuvant PRRT. Publications included case reports, retrospective cohort series and a phase 2 trial. Definitions of unresectable disease were variable. Radioisotopes used included 177Lu (n = 142) and 90Y (n = 36), used separately (n = 178) or in combination (n = 1). A combination of PRRT with chemotherapy was also explored (n = 2). Toxicity data was reported in 11/17 studies. Survival analysis was reported in 3/17 studies. Surgical resection following PRRT was reported for both the primary tumor (n = 71) and metastases (n = 12). Resection rates could not be calculated as not all publications reported whether resection was completed. Published literature exploring the use of PRRT in the neoadjuvant setting is mostly limited to case reports and retrospective cohort studies. From these limited data there is reported to be a role of PRRT in neoadjuvant setting in the literature. However, the low quality of evidence precludes any definite conclusion on the grade of disease, site of primary, isotope used or use of concomitant chemotherapy that can benefit from this application. Further prospective studies will require collaboration between multiple centers to gain sufficient high-quality evidence.

Surgical management of pancreatic neuroendocrine tumors - An EYSAC and E-AHPBA international survey of current practice

INTRODUCTION

Pancreatic neuroendocrine tumors (pNET) exhibit a wide spectrum of clinical behavior, which makes their assessment and management quite challenging. The purpose of this study was to comprehensively assess the existing treatment landscape for patients with pNET.

MATERIALS AND METHODS

The study was conducted with the support of the ESSO-EYSAC Research Academy in collaboration with the E-AHPBA. An online survey was distributed via email and social media to surgical networks across Europe and beyond (September 1-30, 2023).

RESULTS

Overall, 155 complete responses were obtained. A specialized NET tumor board was present at the institutions of 94 (61 %) of the study participants. The most frequently applied guidelines were from ENETS (n = 97; 63 %), NCCN (n = 74; 48 %), and ESMO (n = 53; 34 %). For resectability, similar criteria as in pancreatic ductal adenocarcinoma were used by 111 (72 %) participants, even though 116 (75 %) participants believed that pNET/pNEC should have their own resectability criteria. Most respondents used somatostatin analogues (n = 126; 81 %) and chemotherapy (n = 85; 55 %) as neoadjuvant treatments, followed by molecularly targeted agents (n = 45; 29 %) and PRRT (n = 37; 24 %). Only 17 (11 %) participants agreed/strongly agreed that the management of pNET/pNEC is sufficiently addressed in surgical education programs.

CONCLUSION

This international survey highlighted areas for improvement in the care of pNET, namely the lack of pNET-specific resectability criteria and educational programs addressing pNET management.

Factors Predicting Prognosis in Metastatic Grade 1 Gastro-entero-pancreatic Neuroendocrine Tumors

INTRODUCTION

The incidence of gastroenteropancreatic neuroendocrine tumors (GEP-NET) has steadily increased. These tumors are considered relatively indolent even when metastatic. What determines survival outcomes in such situations is understudied.

MATERIALS AND METHODS

Retrospective analysis of a prospectively maintained NET clinic database, to include patients of metastatic grade 1 GEP-NET, from January 2018 to December 2021, to assess factors affecting progression-free survival (PFS).

RESULTS

Of the 589 patients of GEP-NET treated during the study period, 100 were grade 1, with radiological evidence of distant metastasis. The median age was 50 years, with 67% being men. Of these, 15 patients were observed, while 85 patients received treatment in the form of surgery (n = 32), peptide receptor radionuclide therapy (n = 50), octreotide LAR (n = 22), and/or chemotherapy (n = 4), either as a single modality or multi-modality treatment. The median (PFS) was 54.5 months. The estimated 3-year PFS and 3-year overall survival rates were 72.3% (SE 0.048) and 93.4% (SE 0.026), respectively. On Cox regression, a high liver tumor burden was the only independent predictor of PFS (OR 3.443, p = 0.014). The 5-year OS of patients with concomitant extra-hepatic disease was significantly lower than that of patients with liver-limited disease (70.7% vs. 100%, p = 0.017).

CONCLUSION

A higher burden of liver disease is associated with shorter PFS in patients with metastatic grade I GEP-NETs. The OS is significantly lower in patients with associated extrahepatic involvement. These parameters may justify a more aggressive treatment approach in metastatic grade 1 GEP-NETs.

Safety and Efficacy of 177 Lu-DOTATATE in Children and Young Adult Population : A Single-Center Experience

PURPOSE

This single-center retrospective study explores the safety and efficacy of 177 Lu-DOTATATE in children and young adult population with metastatic/inoperable neuroendocrine tumors (NETs).

PATIENTS AND METHODS

This study is a retrospective analysis of all children and young adult patients (≤29 years) with advanced inoperable/metastatic epithelial or nonepithelial NETs who were administered a median of 4 cycles of 177 Lu-DOTATATE therapy and low-dose oral capecitabine as a radiosensitizer every 8-12 weeks, except 2 patients who received CAPTEM chemotherapy. The radiological response was assessed using RECIST 1.1 on interim and end-of-treatment 68 Ga-DOTANOC PET/CT. The primary endpoint was objective response rate, whereas disease control rate, toxicity profile, progression-free survival, and overall survival were secondary endpoints.

RESULTS

Nineteen biopsy-proven NET patients (median age, 22 ± 10 years) with 8 of them adolescents (10-18 years) and the remaining young adults (19-29 years) were included. Fourteen patients had gastroenteropancreatic neuroendocrine tumor (pancreas being most common primary site), whereas the rest had non-gastroenteropancreatic neuroendocrine tumor. A total of 65 cycles of 177 Lu-DOTATATE (range, 1-6 cycles) were administered with a median cumulative activity of 600 mCi (range, 100-1000 mCi). The objective response rate and disease control rate were 41% and 94%, respectively. Grade 1 and 2 adverse events were observed in 14 (74%) and 5 (26%) of 19 patients, respectively. In a total of 8 events (42%), 4 events each of disease progression and death occurred during a median follow-up of 80.1 months with an estimated 5-year progression-free survival and overall survival of 54% (95% confidence interval, 30-78) and 63% (95% confidence interval, 39-87), respectively.

CONCLUSIONS

177 Lu-DOTATATE appears safe and effective in children and young adults with metastatic/inoperable NETs. Large prospective trials are required to validate these results.

Advances in Radionuclide Therapies for Patients with Neuro-endocrine Tumors

PURPOSE OF REVIEW

To provide insights into the role of peptide receptor radionuclide therapy (PRRT) in patients with advanced neuroendocrine tumors (NET) and an overview of possible strategies to combine PRRT with locoregional and systemic anticancer treatments.

RECENT FINDINGS

Research on combining PRRT with other treatments encompasses a wide variety or treatments, both local (transarterial radioembolization) and systemic therapies, chemotherapy (i.e., capecitabine and temozolomide), targeted therapies (i.e., olaparib, everolimus, and sunitinib), and immunotherapies (e.g., nivolumab and pembrolizumab). Furthermore, PRRT shows promising first results as a treatment prior to surgery. There is great demand to enhance the efficacy of PRRT through combination with other anticancer treatments. While research in this area is currently limited, the field is rapidly evolving with numerous ongoing clinical trials aiming to address this need and explore novel therapeutic combinations.

Efficacy and safety of neoadjuvant therapy in gastroenteropancreatic neuroendocrine neoplasms: A systematic review and meta-analysis

OBJECTIVE

To determine the effectiveness and safety of neoadjuvant therapy in gastroenteropancreatic neuroendocrine neoplasms (GEP-NENs) and provide evidence-based suggestions for clinical treatment.

METHODS

The Cochrane Library, Embase, PubMed, and Web of Science were searched for articles published that analyzed the effectiveness and safety of GEP-NEN-targeted neoadjuvant therapy before March 2023. A confidence interval (CI) of 95%, a subgroup analysis, heterogeneity, and effect size (ES) were analyzed, and a meta-analysis of the literature was performed using the Stata BE17 software.

RESULTS

A total of 417 patients from 13 studies were included in this meta-analysis. The primary variables comprised the objective response rate (ORR), disease control rate (DCR), surgical resection rate, and R0 resection rate with ES values of 0.42 (95% CI: 0.25-0.60), 0.96 (95% CI: 0.93-0.99), 0.67 (95% CI: 0.50-0.84), and 0.60 (95% CI: 0.54-0.67), respectively. The secondary variables were the incidence rates of treatment-related adverse events (TRAEs), Grade 3 or higher TRAEs, and surgical complications with ES values of 0.29 (95% CI: -0.03-0.21), 0.13 (95% CI: -0.07-0.33), and 0.35 (95% CI: 0.27-0.44), respectively.

CONCLUSION

Neoadjuvant therapy is an effective and safe treatment method for GEP-NENs. However, further studies are required to determine the optimal regimen for this therapy in these tumors.

European Neuroendocrine Tumour Society (ENETS) 2023 guidance paper for nonfunctioning pancreatic neuroendocrine tumours

This ENETS guidance paper for well-differentiated nonfunctioning pancreatic neuroendocrine tumours (NF-Pan-NET) has been developed by a multidisciplinary working group, and provides up-to-date and practical advice on the management of these tumours. Using the extensive experience of centres treating patients with NF-Pan-NEN, the authors of this guidance paper discuss 10 troublesome questions in everyday clinical practice. Our many years of experience in this field are still being verified in the light of the results of new clinical, which set new ways of proceeding in NEN. The treatment of NF-Pan-NEN still requires a decision of a multidisciplinary team of specialists in the field of neuroendocrine neoplasms.

Effective Treatment of SSTR2-Positive Small Cell Lung Cancer Using 211At-Containing Targeted α-Particle Therapy Agent Which Promotes Endogenous Antitumor Immune Response

Small cell lung cancer (SCLC) is a neuroendocrine tumor with a high degree of malignancy. Due to limited treatment options, patients with SCLC have a poor prognosis. We have found, however, that intravenously administered octreotide (Oct) armed with astatine-211 ([211At]SAB-Oct) is effective against a somatostatin receptor 2 (SSTR2)-positive SCLC tumor in SCLC tumor-bearing BALB/c nude mice. In biodistribution analysis, [211At]SAB-Oct achieved the highest concentration in the SCLC tumors up to 3 h after injection as time proceeded. A single intravenous injection of [211At]SAB-Oct (370 kBq) was sufficient to suppress SSTR2-positive SCLC tumor growth in treated mice by inducing DNA double-strand breaks. Additionally, a multitreatment course (370 kBq followed by twice doses of 370 kBq for a total of 1110 kBq) inhibited the growth of the tumor compared to the untreated control group without significant off-target toxicity. Surprisingly, we found that [211At]SAB-Oct could up-regulate the expressions of calreticulin and major histocompatibility complex I (MHC-I) on the tumor cell membrane surface, suggesting that α-particle internal irradiation may activate an endogenous antitumor immune response through the regulation of immune cells in the tumor microenvironment, which could synergically enhance the efficacy of immunotherapy. We conclude that [211At]SAB-Oct is a potential new therapeutic option for SSTR2-positive SCLC.

Management of Small Bowel Neuroendocrine Tumours: 10 Years' Experience at a Tertiary Referral Centre

BACKGROUND

Neuroendocrine tumours (NET) arising from the small bowel are clinically challenging and are often diagnosed at advanced stages. Disease control with surgery alone can be demanding. Multimodal treatment concepts integrating surgery and non-surgical modalities could be of benefit.

METHOD

Retrospective review of consecutive adult patients with SB NET treated at Imperial College Healthcare NHS Trust between 1 January 2010 and 31 December 2019. Data regarding clinicopathological characteristics, treatments, and disease trajectory were extracted and summarised. Overall and progression/recurrence-free survival were estimated at 5 and 10 years.

RESULTS

154 patients were identified, with a median age of 64 years (range 33-87); 135/154 (87.7%) had stage III/IV disease at diagnosis. Surgery was used in 125 individuals (81.2%), typically with either segmental small bowel resection (60.8%) or right hemicolectomy (33.6%) and mesenteric lymphadenectomy for the primary tumour. Systemic and/or liver-directed therapies were used in 126 (81.8%); 60 (47.6%) had more than one line of non-surgical treatment. Median follow-up was 67.2 months (range 3.1-310.4); overall survival at 5 and 10 years was 91.0% (95% CI: 84.9-94.7%) and 82.5% (95% CI: 72.9-88.9%), respectively. Imaging-based median progression-free survival was 42.7 months (95% CI: 24.7 to 72.4); 5-year progression-free survival was 63.4% (95% CI: 55.0-70.6%); 10-year progression-free survival was 18.7% (95% CI: 12.4-26.1). Nineteen patients (12.3%) reached 10 years follow-up without disease recurrence and therefore were considered cured.

CONCLUSIONS

Most patients with SB NET present in a metastasised stage. Multimodal treatment concepts may be associated with excellent clinical outcomes. Future work should explore optimal approaches to treatment sequencing and patient selection.

Prognostic factors after resection of locally advanced non-functional pancreatic neuroendocrine neoplasm: an analysis from the German Cancer Registry Group of the Society of German Tumor Centers

OBJECTIVE

The available literature regarding outcome after pancreatic resection in locally advanced non-functional pNEN (LA-pNEN) is sparse. Therefore, this study evaluates the current survival outcomes and prognostic factors in after resection of LA-pNEN.

MATERIALS AND METHODS

This population-based analysis was derived from 17 German cancer registries from 2000 to 2019. Patients with upfront resected non-functional non-metastatic LA-pNEN were included.

RESULTS

Out of 2776 patients with pNEN, 277 met the inclusion criteria. 137 (45%) of the patients were female. The median age was 63 ± 18 years. Lymph node metastasis was present in 45%. G1, G2 and G3 pNEN were found in 39%, 47% and 14% of the patients, respectively. Resection of LA-pNEN resulted in favorable 3-, 5- and 10-year overall survival of 79%, 74%, and 47%. Positive resection margin was the only potentially modifiable independent prognostic factor for overall survival (HR 1.93, 95% CI 1.71-3.69, p value = 0.046), whereas tumor grade G3 (HR 5.26, 95% CI 2.09-13.25, p value < 0.001) and lymphangiosis (HR 2.35, 95% CI 1.20-4.59, p value = 0.012) were the only independent prognostic factors for disease-free survival.

CONCLUSION

Resection of LA-pNEN is feasible and associated with favorable overall survival. G1 LA-pNEN with negative resection margins and absence of lymph node metastasis and lymphangiosis might be considered as cured, while those not fulfilling these criteria might be considered as a high-risk group for disease progression. Herein, negative resection margins represent the only potentially modifiable prognostic factor in LA-pNEN but seem to be influenced by tumor grade.

Deep learning radio-clinical signatures for predicting neoadjuvant chemotherapy response and prognosis from pretreatment CT images of locally advanced gastric cancer patients

BACKGROUND

Early noninvasive screening of patients who would benefit from neoadjuvant chemotherapy (NCT) is essential for personalized treatment of locally advanced gastric cancer (LAGC). The aim of this study was to identify radio-clinical signatures from pretreatment oversampled computed tomography (CT) images to predict the response to NCT and prognosis of LAGC patients.

METHODS

LAGC patients were retrospectively recruited from six hospitals from January 2008 to December 2021. An SE-ResNet50-based chemotherapy response prediction system was developed from pretreatment CT images preprocessed with an imaging oversampling method (i.e. DeepSMOTE). Then, the deep learning (DL) signature and clinic-based features were fed into the deep learning radio-clinical signature (DLCS). The predictive performance of the model was evaluated based on discrimination, calibration, and clinical usefulness. An additional model was built to predict overall survival (OS) and explore the survival benefit of the proposed DL signature and clinicopathological characteristics.

RESULTS

A total of 1060 LAGC patients were recruited from six hospitals; the training cohort (TC) and internal validation cohort (IVC) patients were randomly selected from center I. An external validation cohort (EVC) of 265 patients from five other centers was also included. The DLCS exhibited excellent performance in predicting the response to NCT in the IVC [area under the curve (AUC), 0.86] and EVC (AUC, 0.82), with good calibration in all cohorts ( P >0.05). Moreover, the DLCS model outperformed the clinical model ( P <0.05). Additionally, we found that the DL signature could serve as an independent factor for prognosis [hazard ratio (HR), 0.828, P =0.004]. The concordance index (C-index), integrated area under the time-dependent ROC curve (iAUC), and integrated Brier score (IBS) for the OS model were 0.64, 1.24, and 0.71 in the test set.

CONCLUSION

The authors proposed a DLCS model that combined imaging features with clinical risk factors to accurately predict tumor response and identify the risk of OS in LAGC patients prior to NCT, which can then be used to guide personalized treatment plans with the help of computerized tumor-level characterization.

Peptide Receptor Radionuclide Therapy (PRRT): Innovations and Improvements

Neuroendocrine neoplasms (NENs) are tumors originating from neuroendocrine cells distributed throughout the human body. With an increasing incidence over the past few decades, they represent a highly heterogeneous group of neoplasms, mostly expressing somatostatin receptors (SSTRs) on their cell surface. Peptide receptor radionuclide therapy (PRRT) has emerged as a crucial strategy for treating advanced, unresectable neuroendocrine tumors by administering radiolabeled somatostatin analogs intravenously to target SSTRs. This article will focus on the multidisciplinary theranostic approach, treatment effectiveness (such as response rates and symptom relief), patient outcomes, and toxicity profile of PRRT for NEN patients. We will review the most significant studies, such as the phase III NETTER-1 trial, and discuss promising new radiopharmaceuticals, including alpha-emitting radionuclide-labeled somatostatin analogs and SSTR antagonists.

Peptide Receptor Radionuclide Therapy (PRRT): Innovations and Improvements

Neuroendocrine neoplasms (NENs) are tumors originating from neuroendocrine cells distributed throughout the human body. With an increasing incidence over the past few decades, they represent a highly heterogeneous group of neoplasms, mostly expressing somatostatin receptors (SSTRs) on their cell surface. Peptide receptor radionuclide therapy (PRRT) has emerged as a crucial strategy for treating advanced, unresectable neuroendocrine tumors by administering radiolabeled somatostatin analogs intravenously to target SSTRs. This article will focus on the multidisciplinary theranostic approach, treatment effectiveness (such as response rates and symptom relief), patient outcomes, and toxicity profile of PRRT for NEN patients. We will review the most significant studies, such as the phase III NETTER-1 trial, and discuss promising new radiopharmaceuticals, including alpha-emitting radionuclide-labeled somatostatin analogs and SSTR antagonists.

Controversy Over Liver Transplantation or Resection for Neuroendocrine Liver Metastasis: Tumor Biology Cuts the Deal

BACKGROUND

In patients with neuroendocrine liver metastasis (NELM), liver transplantation (LT) is an alternative to liver resection (LR), although the choice of therapy remains controversial. In this multicenter study, we aim to provide novel insight in this dispute.

METHODS

Following a systematic literature search, 15 large international centers were contacted to provide comprehensive data on their patients after LR or LT for NELM. Survival analyses were performed with the Kaplan-Meier method, while multivariable Cox regression served to identify factors influencing survival after either transplantation or resection. Inverse probability weighting and propensity score matching was used for analyses with balanced and equalized baseline characteristics.

RESULTS

Overall, 455 patients were analyzed, including 230 after LR and 225 after LT, with a median follow-up of 97 months [95% confidence interval (CI): 85-110 months]. Multivariable analysis revealed G3 grading as a negative prognostic factor for LR [hazard ratio (HR)=2.22, 95% CI: 1.04-4.77, P =0.040], while G2 grading (HR=2.52, 95% CI: 1.15-5.52, P =0.021) and LT outside Milan criteria (HR=2.40, 95% CI: 1.16-4.92, P =0.018) were negative prognostic factors in transplanted patients. Inverse probability-weighted multivariate analyses revealed a distinct survival benefit after LT. Matched patients presented a median overall survival (OS) of 197 months (95% CI: 143-not reached) and a 73% 5-year OS after LT, and 119 months (95% CI: 74-133 months) and a 52.8% 5-year OS after LR (HR=0.59, 95% CI: 0.3-0.9, P =0.022). However, the survival benefit after LT was lost if patients were transplanted outside Milan criteria.

CONCLUSIONS

This multicentric study in patients with NELM demonstrates a survival benefit of LT over LR. This benefit depends on adherence to selection criteria, in particular low-grade tumor biology and Milan criteria, and must be balanced against potential risks of LT.

68 Ga-DOTATOC PET/CT Imaging of a Muscular Solitary Fibrous Tumor

ABSTRACT

A 73-year-old woman was referred for 68 Ga-DOTATOC PET/CT staging of a grade 2 pancreatic neuroendocrine tumor, which showed the primary pancreatic tumor, liver metastases, one left pleural metastasis, and high uptake in a mass of the right triceps brachii muscle. Two years before, she underwent 18 F-FDG PET/CT and 111 In-pentetreotide scan, respectively, with low and high uptake of each radiotracer in the triceps mass. Histopathological analysis revealed a solitary fibrous tumor. Immunohistochemistry showed no staining for SSTR-2 and SSTR-5, suggesting tumor overexpression of another somatostatin receptor. This case highlighted a potential pitfall on 68 Ga-DOTATOC PET/CT.

Gastro-Enteric-Pancreatic Neuroendocrine Tumor Treatment: 177Lu-DOTATATE

177Lu-DOTA-TATE therapy is a highly effective therapy in metastatic, well-differentiated, somatostatin receptor-positive GEP-neuroendocrine tumors (NETs) with mostly tolerable adverse effects. Guidelines generally refer to peptide receptor radionuclide therapy as a second-line therapy after SSA in gastroenteric and second- or third-line therapy in pancreatic NETs to improve survival rates and quality of life. Although we do not have sufficient data, 177Lu-DOTA-TATE therapy may also have a role in high-grade NET therapy, mostly in combination with other treatments such as chemotherapy.

Defining a New Classification System for the Surgical Management of Neuroendocrine Tumor Liver Metastases

Although rarely curative, hepatic cytoreduction of neuroendocrine tumor liver metastases (NETLM) is associated with improved symptom control and prolonged survival. Preoperative 68Ga DOTATATE and gadoxetic acid-enhanced liver MRI can improve characterization of hepatic disease extent to improve surgical clearance, and resection of the primary tumor is associated with improved survival regardless of whether the liver metastases are treated. As parenchymal-sparing surgical techniques and the lowering of the debulking threshold have expanded the numbers of eligible NETLM patients for hepatic cytoreduction, we propose a new classification system to help guide surgical management. A multimodal approach that includes surgery, liver-directed therapies, and systemic therapies has improved outcomes and increased longevity for patients with well-differentiated metastatic NET.

Imaging Recommendations for Theranostic PET-CT in Oncology

We in this article have presented a review of the guideline recommendations on theranostic positron emission tomography-computed tomography (PET-CT) imaging which will be helpful to assist practitioners in providing appropriate patient care. Multiple guidelines by different societies and medical associations provide standards for diagnosis, imaging, and treatment of cancer patients. They have generated a number of recommendations related to 68Ga-DOTATATE and 68Ga-PSMA-11 PET-CT, which are the classical examples of theranostic PET-CT imaging in current practice.

Clinical Pharmacology of Radiotheranostics in Oncology

The combined use of diagnostic and therapeutic radioligands with the same molecular target, also known as theranostics, enables accurate patient selection, targeted therapy, and prediction of treatment response. Radioiodine, bone-seeking radioligands and norepinephrine analogs have been used for many years for diagnostic imaging and radioligand therapy of thyroid carcinoma, bone metastases, pheochromocytoma, paraganglioma, and neuroblastoma, respectively. In recent years, radiolabeled somatostatin analogs and prostate-specific membrane antigen ligands have shown clinical efficacy in the treatment of neuroendocrine tumors and prostate cancer, respectively. Several candidate compounds are targeting novel theranostic targets such as fibroblast activation protein, C-X-C chemokine receptor 4, and gastrin-releasing peptide receptor. In addition, several strategies to improve efficacy of radioligand therapy are being evaluated, including dosimetry-based dose optimization, multireceptor targeting, upregulation of target receptors, radiosensitization, pharmacogenomics, and radiation genomics. Design and evaluation of novel radioligands and optimization of dose and dose schedules, within the complex context of individualized multimodal cancer treatment, requires a multidisciplinary approach that includes clinical pharmacology. Significant increases in the use of these radiopharmaceuticals in routine oncological practice can be expected, which will have major impact on patient care as well as (radio)pharmacy utilization.

Radioligand therapy (RLT) as neoadjuvant treatment for inoperable pancreatic neuroendocrine tumors: a literature review

In the last 10 years, several literature reports supported radioligand therapy (RLT) in neoadjuvant settings for pancreatic neuroendocrine tumors (PanNETs). Indeed, primary tumor shrinkage has been frequently reported following RLT in unresectable or borderline resectable PanNETs. Moreover, RLT-induced intratumoral modifications facilitate surgery, both on primary tumor and metastasis, having a great impact on progression free survival (PFS), overall survival (OS) and quality of life (QoL). However, prospective controlled investigations are necessary to confirm preliminary data and to define the best RLT scheme and the ideal patient that, in a multidisciplinary approach, should be referred to neoadjuvant RLT.

Safety and efficacy of peptide receptor radionuclide therapy with 177Lu-DOTA-EB-TATE in patients with metastatic neuroendocrine tumors

Rationale: This study aimed to assess the safety, efficacy, and survival of 177Lu-DOTA-EB-TATE in patients with metastatic neuroendocrine tumors (NETs). Methods: Thirty patients with metastatic NETs were prospectively enrolled and treated with 177Lu-DOTA-EB-TATE (3 intended cycles at 8 to 12-week intervals, 3.7 GBq/cycle). Treatment-related adverse events were graded according to the National Cancer Institute Common Terminology Criteria for Adverse Events (CTCAE), version 5.0. The treatment response was graded according to RECIST 1.1 and PERCIST 1.0 criteria. Kaplan-Meier analysis was performed to calculate progression-free survival (PFS) and overall survival (OS). Results: Patients tolerated therapy well without acute adverse effects. During peptide receptor radionuclide therapy (PRRT), no grade 4 toxicity was observed in any of the patients; grade 3 hematotoxicity was recorded in 4 patients, including grade 3 thrombocytopenia in 4 patients (13.3%) and grade-3 anemia in 1 patient (3.3%); grade 3 hepatotoxicity was recorded in 1 (3.3%) patient, and no grade 2/3/4 nephrotoxicity was observed. On long-term follow-up, none of the patients developed grade 4 hematotoxicity or nephrotoxicity of any grade, reversible grade 3 hematotoxicity (thrombocytopenia) occurred in 1 patient. There was no incidence of leukemia or myelodysplastic syndrome for the duration of follow-up. Of 27 patients with RECIST-measurable disease, partial response and stable disease were seen in 9 and 14 patients, respectively, resulting in a response rate of 33.3% and disease control rate of 85.2%. Of 29 patients evaluable for response on 68Ga-DOTATATE PET/CT, 14 had partial response and 11 had stable disease, with a response rate of 48.3% and disease control rate of 86.2%. The follow-up period ranged from 5 to 57 months after the first 177Lu-DOTA-EB-TATE PRRT with a median follow-up of 46 months. The median PFS was 36 months, and the median OS was not reached. Ki-67 index of greater than 10% was associated with poorer PFS (P = 0.012). Conclusions: Our results suggest that PRRT with approximately 3.7 GBq 177Lu-DOTA-EB-TATE has acceptable toxicity profile and is effective in treating metastatic NET with high disease control rate. In addition, 177Lu-DOTA-EB-TATE achieved a favorable survival outcome with encouraging PFS.

Factors Contributing to Tumor Shrinkage after Peptide Receptor Radionuclide Therapy in Patients with Unresectable Neuroendocrine Tumors

Peptide receptor activation therapy (PRRT) is a promising treatment option for metastatic neuroendocrine tumors (NETs). However, predicting tumor shrinkage before treatment is challenging. We analyzed the shrinkage rate of each metastatic tumor lesion to identify predictive factors related to shrinkage. Patients with metastatic NET who underwent PRRT were included in this retrospective study. For each patient, between one to five metastatic lesions were selected in descending order of size, and the change in the maximum tumor diameter after treatment was defined as the shrinkage rate per lesion (L-SR). We analyzed the relationship between pretreatment clinicopathological factors and L-SR. The median L-SR of all 75 lesions in 20 patients was 20% (95% CI: 4.8−26.1%). While previous treatment with cytotoxic agents (34.4%, p < 0.05) and primary tumor of the pancreas (27.8%, p < 0.05) were significantly favorable factors, a primary tumor of the rectum was significantly more resistant to shrinkage (−20.5%, p < 0.001). Therefore, lesion-based analysis of PRRT for NETs showed that pancreatic NET and previous treatment with cytotoxic agents were favorable factors for tumor shrinkage; however, rectal NET was a factor associated with resistance to shrinkage.

Role of surgical treatments in high-grade or advanced gastroenteropancreatic neuroendocrine neoplasms

Over the last 40 years, the incidence and prevalence of gastroenteropancreatic neuroendocrine neoplasms (GEP-NENs) have continued to increase. Compared to other epithelial neoplasms in the same organ, GEP-NENs exhibit indolent biological behavior, resulting in more chances to undergo surgery. However, the role of surgery in high-grade or advanced GEP-NENs is still controversial. Surgery is associated with survival improvement of well-differentiated high-grade GEP-NENs, whereas poorly differentiated GEP-NENs that may benefit from resection require careful selection based on Ki67 and other tissue biomarkers. Additionally, surgery also plays an important role in locally advanced and metastatic disease. For locally advanced GEP-NENs, isolated major vascular involvement is no longer an absolute contraindication. In the setting of metastatic GEP-NENs, radical intended surgery is recommended for patients with low-grade and resectable metastases. For unresectable metastatic disease, a variety of surgical approaches, including cytoreduction of liver metastasis, liver transplantation, and surgery after neoadjuvant treatment, show survival benefits. Primary tumor resection in GEP-NENs with unresectable metastatic disease is associated with symptom control, prolonged survival, and improved sensitivity toward systemic therapies. Although there is no established neoadjuvant or adjuvant strategy, increasing attention has been given to this emerging research area. Some studies have reported that neoadjuvant therapy effectively reduces tumor burden, improves the effectiveness of subsequent surgery, and decreases surgical complications.

New Insights in PRRT: Lessons From 2021

Peptide receptor radionuclide therapy (PRRT) using radiolabeled somatostatin analogs has been used for over two decades for the treatment of well-differentiated neuroendocrine tumors (NETs), and the publication of the NETTER-1 trials has further strengthened its clinical use. However, many aspects of this treatment are still under discussion. The purpose of this review is to collect and discuss the new available evidence, published in 2021, on the use of 177Lu-Oxodotreotide (DOTATATE) or 90Y-Edotreotide (DOTATOC) in adult patients with NETs focusing on the following hot topics: 1) PRRT use in new clinical settings, broaden its indications; 2) the short- and long-term safety; and 3) the identification of prognostic and predictive factors. The review suggests a possible future increase of PRRT applications, using it in other NETs, as a neoadjuvant treatment, or for rechallenge. Regarding safety, available studies, even those with long follow-up, supported the low rates of adverse events, even though 1.8% of treated patients developed a second malignancy. Finally, there is a lack of prognostic and predictive factors for PRRT, with the exception of the crucial role of nuclear imaging for both patient selection and treatment response estimation.

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

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

Therapeutic strategies for gastroenteropancreatic neuroendocrine neoplasms: State-of-the-art and future perspectives

Although gastroenteropancreatic neuroendocrine neoplasms (GEP-NENs) have always been considered rare tumors, their incidence has risen over the past few decades. They represent a highly heterogeneous group of neoplasms with several prognostic factors, including disease stage, proliferative index (Ki67), and tumor differentiation. Most of these neoplasms express somatostatin receptors on the cell surface, a feature that has important implications in terms of prognosis, diagnosis, and therapy. Although International Guidelines propose algorithms aimed at guiding therapeutic strategies, GEP-NEN patients are still very different from one another, and the need for personalized treatment continues to increase. Radical surgery is always the best option when feasible; however, up to 80% of cases are metastatic upon diagnosis. Regarding medical treatments, as GEP-NENs are characterized by relatively long overall survival, multiple therapy lines are adopted during the lifetime of these patients, but the optimum sequence to be followed has never been clearly defined. Furthermore, although new molecular markers aimed at predicting the response to therapy, as well as prognostic scores, are currently being studied, their application is still far from being part of daily clinical practice. As they represent a complex disease, with therapeutic protocols that are not completely standardized, GEP-NENs require a multidisciplinary approach. This review will provide an overview of the available therapeutic options for GEP-NENs and attempts to clarify the possible approaches for the management of these patients and to discuss future perspectives in this field.

Radiolabeled Somatostatin Analogs-A Continuously Evolving Class of Radiopharmaceuticals

Somatostatin receptors (SSTs) are recognized as favorable molecular targets in neuroendocrine tumors (NETs) and neuroendocrine neoplasms (NENs), with subtype 2 (SST₂) being the predominantly and most frequently expressed. PET/CT imaging with ⁶⁸Ga-labeled SST agonists, e.g., ⁶⁸Ga-DOTA-TOC (SomaKit TOC^®) or ⁶⁸Ga-DOTA-TATE (NETSPOT^®), plays an important role in staging and restaging these tumors and can identify patients who qualify and would potentially benefit from peptide receptor radionuclide therapy (PRRT) with the therapeutic counterparts ¹⁷⁷Lu-DOTA-TOC or ¹⁷⁷Lu-DOTA-TATE (Lutathera^®). This is an important feature of SST targeting, as it allows a personalized treatment approach (theranostic approach). Today, new developments hold promise for enhancing diagnostic accuracy and therapeutic efficacy. Among them, the use of SST₂ antagonists, such as JR11 and LM3, has shown certain advantages in improving image sensitivity and tumor radiation dose, and there is evidence that they may find application in other oncological indications beyond NETs and NENs. In addition, PRRT performed with more cytotoxic α-emitters, such as ²²⁵Ac, or β^- and Auger electrons, such as ¹⁶¹Tb, presents higher efficacy. It remains to be seen if any of these new developments will overpower the established radiolabeled SST analogs and PRRT with β^--emitters.

Value of Peptide Receptor Radionuclide Therapy as Neoadjuvant Treatment in the Management of Primary Inoperable Neuroendocrine Tumors

INTRODUCTION

Neuroendocrine neoplasms including neuroendocrine tumors (NETs) are often diagnosed as primary disseminated or inoperable. In those cases, systemic extensive therapy is necessary, but radical treatment is unlikely. As described in the literature, in some selected cases, peptide receptor radionuclide therapy (PRRT) may be used as a first-line/neoadjuvant therapy that allows further successful surgery. Such treatment may enable a reduction of total tumor burden or allow a radical treatment which improves the final outcomes.

AIM

This study aims to assess whether neoadjuvant PRRT could be a treatment option for patients with initially unresectable NETs.

METHODS

Among the group of 114 patients treated with PRRT between the years 2005 and 2020, in 32 cases, it was the first-line therapy, mainly due to massive disease burden at the time of diagnosis. Among them, nine patients received PRRT as the first-line treatment due to the primary inoperable tumors with the intention of preoperative reduction of the tumor size in order to allow for a surgical treatment.

RESULTS

Neoadjuvant PRRT enabled surgery in four out of nine (45%) patients. Finally, in two out of four cases, the goal (radical surgery) has been achieved.

CONCLUSION

PRRT may be considered not only as a palliative but also as a neoadjuvant therapy in advanced, somatostatin-positive NETs that were initially inoperable.

Targeted Cancer Therapy: What's New in the Field of Neuroendocrine Neoplasms?

Neuroendocrine tumors (NETs) are a heterogeneous family of neoplasms of increasing incidence and high prevalence due to their relatively indolent nature. Their wide anatomic distribution and their characteristic ability to secrete hormonally active substances pose unique challenges for clinical management. They are also characterized by the common expression of somatostatin receptors, a target that has been extremely useful for diagnosis and treatment (i.e., somatostatin analogues (SSAs) and peptide-receptor radionuclide therapy (PRRT)). Chemotherapy is of limited use for NETs of non-pancreatic origin, and the only approved targeted agents for advanced progressive NETs are sunitinib for those of pancreatic origin, and everolimus for lung, gastrointestinal and pancreatic primaries. Despite recent therapeutic achievements, thus, systemic treatment options remain limited. In this review we will discuss the state-of-the-art targeted therapies in the field of NETs, and also future perspectives of novel therapeutic drugs or strategies in clinical development, including recently presented results from randomized trials of yet unapproved antiangiogenic agents (i.e., pazopanib, surufatinib and axitinib), PRRT including both approved radiopharmaceuticals (177Lu-Oxodotreotide) and others in development (177Lu-Edotreotide, 177Lu-Satoreotide Tetraxetan), immunotherapy and other innovative targeted strategies (antibody-drug conjugates, bites,…) that shall soon improve the landscape of personalized treatment options in NET patients.