First-in-Humans Application of 161Tb: A Feasibility Study Using 161Tb-DOTATOC

161Tb has decay properties similar to those of 177Lu but, additionally, emits a substantial number of conversion and Auger electrons. The aim of this study was to apply 161Tb in a clinical setting and to investigate the feasibility of visualizing the physiologic and tumor biodistributions of 161Tb-DOTATOC. Methods:161Tb was shipped from Paul Scherrer Institute, Villigen-PSI, Switzerland, to Zentralklinik Bad Berka, Bad Berka, Germany, where it was used for the radiolabeling of DOTATOC. In 2 separate studies, 596 and 1,300 MBq of 161Tb-DOTATOC were administered to a 35-y-old male patient with a metastatic, well-differentiated, nonfunctional malignant paraganglioma and a 70-y-old male patient with a metastatic, functional neuroendocrine neoplasm of the pancreatic tail, respectively. Whole-body planar γ-scintigraphy images were acquired over a period of several days for dosimetry calculations. SPECT/CT images were reconstructed using a recently established protocol and visually analyzed. Patients were observed for adverse events after the application of 161Tb-DOTATOC. Results: The radiolabeling of DOTATOC with 161Tb was readily achieved with a high radiochemical purity suitable for patient application. Planar images and dosimetry provided the expected time-dependent biodistribution of 161Tb-DOTATOC in the liver, kidneys, spleen, and urinary bladder. SPECT/CT images were of high quality and visualized even small metastases in bones and liver. The application of 161Tb-DOTATOC was well tolerated, and no related adverse events were reported. Conclusion: This study demonstrated the feasibility of imaging even small metastases after the injection of relatively low activities of 161Tb-DOTATOC using γ-scintigraphy and SPECT/CT. On the basis of this essential first step in translating 161Tb to clinics, further efforts will be directed toward the application of 161Tb for therapeutic purposes.

Feasibility, Biodistribution and Preliminary Dosimetry in Peptide-Targeted Radionuclide Therapy (PTRT) of Diverse Adenocarcinomas using 177Lu-FAP-2286: First-in-Human Results

Fibroblast activation protein (FAP) is a promising target for diagnosis and therapy of numerous malignant tumors. FAP-2286 is the conjugate of a FAP-binding peptide, which can be labeled with radionuclides for theranostic applications. We present the first-in-human results using ¹⁷⁷Lu-FAP-2286 for peptide-targeted radionuclide therapy (PTRT). Methods: PTRT using ¹⁷⁷Lu-FAP-2286 was performed in 11 patients with advanced adenocarcinomas of pancreas, breast, rectum and ovary after prior confirmation of uptake on ⁶⁸Ga-FAP-2286/-FAPI-04- PET/CT. Results: Administration of ¹⁷⁷Lu-FAP-2286 (5.8 ± 2.0 GBq; range, 2.4-9.9 GBq) was well tolerated, with no adverse symptoms or clinically detectable pharmacologic effects being noticed or reported in any of the patients. The whole-body effective doses were 0.07 ± 0.02 Gy/GBq (range 0.04 - 0.1). The mean absorbed doses for kidneys and red marrow were 1.0 ± 0.6 Gy/GBq (range 0.4 - 2.0) and 0.05 ± 0.02 Gy/GBq (range 0.03 - 0.09), respectively. Significant uptake and long tumor retention of ¹⁷⁷Lu-FAP-2286 resulted in high absorbed tumor doses, e.g., 3.0 ± 2.7 Gy/GBq (range 0.5 - 10.6) in bone metastases. No grade (G) 4 adverse events were observed. G3 events occurred in 3 patients - 1 pancytopenia, 1 leukocytopenia and 1 pain flare-up; 3 patients reported pain-response. Conclusion: ¹⁷⁷Lu-FAP-2286 PTRT, applied in a broad spectrum of cancers, was relatively well-tolerated with acceptable side effects and demonstrated long retention of the radiopeptide. Prospective clinical studies are warranted.

The impact of the extent of the bone involvement on overall survival and toxicity in mCRPC patients receiving [177Lu]Lu-PSMA-617: a WARMTH multicentre study

INTRODUCTION

Prostate-specific membrane antigen (PSMA)-based radioligand therapy (RLT) showed in a multicentre WARMTH (World Association of Radiopharmaceutical and Molecular Therapy) study that the presence of bone metastases is a negative prognosticator for the survival. The current multicentre retrospective analysis aims to evaluate the response rate to RLT, the overall survival (OS) of patients and the safety of the treatment according to the extent of bone involvement.

METHODS

The study included patients with progressive metastatic castration-resistant prostate cancer (mCRPC), who underwent RLT with [¹⁷⁷Lu]Lu-PSMA-617 and a follow-up of at least 6 months. Tumour burden in the bone was classified prior to RLT as follows: less than 6 lesions, 6-20 lesions, more than 20 lesions and diffuse involvement. The response rate was evaluated using changes of the prostate-specific antigen (PSA) after the first treatment cycle. Overall survival was calculated from the date of the first treatment. Haematological adverse events were classified according to Common Terminology Criteria for Adverse Events (CTCAE), version 5.0.

RESULTS

A total of 319 males were included in the analysis. The extent of bone metastases and PSA response did not correlate significantly. Any PSA decline was observed in 73% patients; 44% showed a decline of ≥50%. The median OS of patient in the different subgroups was 18 months (less than 6 lesions), 13 months (6-20 lesions), 11 months (more than 20 lesions) and 8 months (diffuse involvement), respectively (p < 0.0001). Patients with prior Ra-223-therapy showed longer OS in all subgroups, especially in the subgroups with 6-20 lesions (OS: 16 vs. 12 months; p = 0.038) as well as diffuse involvement (OS: 11 vs. 7 months; p = 0.034). Significant negative prognosticators of OS were the existence of liver metastases in all subgroups and prior chemotherapy in patients with <6 bone lesions. Anaemia and thrombocytopenia correlated positively with the extent of bone metastases: p < 0.0001 and 0.005, respectively. No patient showed a high grade leukopenia.

CONCLUSION

The extent of bone involvement correlated negatively with the OS after RLT; however, it showed no relevant correlation with the PSA response rate. Prior therapy with Ra-223 may have a positive impact on OS. Haematotoxicity was higher in patients with more than 20 bone lesions; nevertheless, the majority of these patients did not show a relevant haematotoxicity.

Symptom Diaries of Patients with Midgut Neuroendocrine Tumors Treated with 177Lu-DOTATATE

We report the impact of 177Lu DOTATATE treatment on abdominal pain, diarrhea, and flushing, symptoms that patients with advanced midgut neuroendocrine tumors (NETs) often find burdensome. Methods: All patients enrolled in the international randomized phase 3 Neuroendocrine Tumors Therapy (NETTER-1) trial (177Lu-DOTATATE plus standard-dose octreotide long-acting repeatable [LAR], n = 117; high-dose octreotide LAR, n = 114) were asked to record the occurrence of predefined symptoms in a daily diary. Change from baseline in symptom scores (mean number of days with a symptom) was analyzed using a mixed model for repeated measures. Results: Patients (intent-to-treat) who received 177Lu-DOTATATE experienced a significantly greater decline from baseline in symptom scores than patients who received high-dose octreotide LAR. For 177Lu-DOTATATE, the mean decline in days with abdominal pain, diarrhea, and flushing was 4.10, 4.55, and 4.52 days per 4 weeks, respectively, compared with 0.99, 1.44, and 2.54 days for high-dose octreotide LAR. The mean differences were 3.11 days (95% confidence interval, 1.35-4.88; P = 0.0007) for abdominal pain, 3.11 days (1.18-5.04; P = 0.0017) for diarrhea, and 1.98 days (0.08-3.88; P = 0.0413) for flushing, favoring 177Lu-DOTATATE. A positive repeated measures correlation was found between diary-recorded symptom scores and questionnaire-recorded pain, diarrhea, and flushing. Conclusion: In addition to efficacy and quality of life benefits, symptom diaries from NETTER-1 demonstrated that treatment with 177Lu DOTATATE was associated with statistically significant reductions in abdominal pain, diarrhea, and flushing, constituting the core symptoms of patients with progressive midgut NETs, compared with high-dose octreotide LAR, supporting a beneficial effect of 177Lu DOTATATE on HRQoL.

A combination of surgery, theranostics, and liquid biopsy - a personalised oncologic approach to treatment of patients with advanced metastatic neuroendocrine neoplasms

Rationale: Neuroendocrine neoplasia (NEN) of small bowel (SBNEN) frequently present with metastatic disease. Theranostics (molecular imaging followed by targeting therapy) allow for personalised medicine. Liquid biopsies enable precise identification of residual disease and real-time monitoring of therapeutic response. Our aim was to determine the clinical utility of a combination of surgery, theranostics, and a multigene blood measurement in metastasised SBNEN. Methods: Inclusion criteria were SBNEN, G1/G2 NEN, initial tumour diagnosis, stage IV NEN, positivity on 68Ga somatostatin analogue PET/CT, eligible for surgery, and 177Lu peptide receptor radionuclide therapy (PRRT). Blood samples for NETest were collected longitudinally. Progression-free survival (PFS) and overall survival (OS) were calculated. NETest results were assessed prior to surgery and during clinical follow-up. Results: A surgical cohort of 39 SBNEN patients met eligibility criteria. Thirty-two patients underwent ileal resection and 7 right hemicolectomy. The mean number of 177Lu PRRT cycles was 4. Mortality was nil. Surgical morbidity was 10.3%. Transient grade 1/2 toxicity occurred in 41% (PRRT). NETest scores (n=9 patients) decreased in 100% following treatment and correlated with diminished tumour volume and disease stabilization following surgery and PRRT. Median follow-up: 78 months. Median PFS and OS: 42.7 and 110 months, respectively. Progression-free survival at 1-, 3-, and 5-years was 79.4%, 57.1% and 40.5%, respectively. Overall survival at 1-, 3-, and 5-years was 97.4%, 97.4%, and 94.1%, respectively. Conclusions: Surgery combined with 177Lu PRRT is safe and provides favourable PFS and OS in selected patients with advanced SBNEN. Liquid biopsy (NETest) has the potential to accurately delineate disease status.

Therapy-related myeloid neoplasm after peptide receptor radionuclide therapy (PRRT) in 1631 patients from our 20 years of experiences: prognostic parameters and overall survival

PURPOSE

To determine prognostic factors and overall survival (OS) in therapy-related myeloid neoplasm (t-MN) of patients after receiving peptide receptor radionuclide therapy (PRRT).

METHODS

All patients treated from February 1999 until September 2019 at our center who had bone marrow biopsy-proven t-MN after PRRT were included. Patient characteristics, laboratory results, and all tumor-directed therapies before t-MN diagnosis were collected. Cox regression analysis was performed to identify parameters associated with OS. Receiver operating characteristic (ROC) curve analysis was used to define cutoff values as well as sensitivity and specificity of the parameters.

RESULTS

Out of 1631 patients treated with PRRT, 30 patients developed t-MN comprising myelodysplastic syndrome (MDS) in 23 patients (77%) and acute myeloid leukemia (AML) in 7 patients (23%). The median OS of t-MN patients was 13 months (range 9.1-16.9 months): 6 months for AML and 15 months for the MDS subgroup, respectively. Higher platelet level was a significant prognostic parameter for longer OS (hazard ratio (HR): 0.99, P < 0.05). Using ROC analysis, the best cutoff value for thrombocyte count was 183.5 Gpt/L, resulting in a sensitivity of 92.3% and a specificity of 50%. Other factors, such as hemoglobin level, did not show a significant correlation with OS.

CONCLUSION

Even rarely occurred, the OS is gravely compromised in t-MN patients after PRRT, and even less in the AML subgroup (6 months). Higher platelet value was a significant prognostic parameter for longer OS in t-MN patients.

Does the proteasome inhibitor bortezomib sensitize to DNA-damaging therapy in gastroenteropancreatic neuroendocrine neoplasms? - A preclinical assessment in vitro and in vivo

BACKGROUND

Well-differentiated gastroenteropancreatic neuroendocrine neoplasms are rare tumors with a slow proliferation. They are virtually resistant to many DNA-damaging therapeutic approaches, such as chemo- and external beam therapy, which might be overcome by DNA damage inhibition induced by proteasome inhibitors such as bortezomib.

METHODS AND RESULTS

In this study, we assessed several combined treatment modalities in vitro and in vivo. By cell-based functional analyses, in a 3D in ovo and an orthotopic mouse model, we demonstrated sensitizing effects of bortezomib combined with cisplatin, radiation and peptide receptor radionuclide therapy (PRRT). By gene expression profiling and western blot, we explored the underlying mechanisms, which resulted in an impaired DNA damage repair. Therapy-induced DNA damage triggered extrinsic proapoptotic signaling as well as the induction of cell cycle arrest, leading to a decreased vital tumor volume and altered tissue composition shown by magnetic resonance imaging and F-18-FDG-PET in vivo, however with no significant additional benefit related to PRRT alone.

CONCLUSIONS

We demonstrated that bortezomib has short-term sensitizing effects when combined with DNA damaging therapy by interfering with DNA repair in vitro and in ovo. Nevertheless, due to high tumor heterogeneity after PRRT in long-term observations, we were not able to prove a therapeutic advantage of bortezomib-combined PRRT in an in vivo mouse model.

Immunoprofiling in Neuroendocrine Neoplasms Unveil Immunosuppressive Microenvironment

Checkpoint inhibitors have shown promising results in a variety of tumors; however, in neuroendocrine tumors (NET) and neuroendocrine carcinomas (NEC), low response rates were reported. We aimed herein to investigate the tumor immune microenvironment in NET/NEC to determine whether checkpoint pathways like programmed cell death protein 1 (PD-1)/programmed death-ligand 1 (PD-L1) might play a role in immune escape and whether other escape mechanisms might need to be targeted to enable a functional antitumor response. Forty-eight NET and thirty NEC samples were analyzed by immunohistochemistry (IHC) and mRNA immunoprofiling including digital spatial profiling. Through IHC, both NET/NEC showed stromal, but less intratumoral CD3+ T cell infiltration, although this was significantly higher in NEC compared to NET. Expression of PD1, PD-L1, and T cell immunoglobulin and mucin domain-containing protein 3 (TIM3) on immune cells was low or nearly absent. mRNA immunoprofiling revealed low expression of IFNγ inducible genes in NET and NEC without any spatial heterogeneity. However, we observed an increased mRNA expression of chemokines, which attract myeloid cells in NET and NEC, and a high abundance of genes related to immunosuppressive myeloid cells and genes with immunosuppressive functions like CD47 and CD74. In conclusion, NET and NEC lack signs of an activation of the adaptive immune system, but rather show abundance of several immunosuppressive genes that represent potential targets for immunomodulation.

Molecular profiling of neuroendocrine tumours to predict response and toxicity to peptide receptor radionuclide therapy

Peptide receptor radionuclide therapy (PRRT) is a type of radiotherapy that targets peptide receptors and is typically used for neuroendocrine tumours (NETs). Some of the key challenges in its use are the prediction of efficacy and toxicity, patient selection, and response optimisation. In this Review, we assess current knowledge on the molecular profile of NETs and the strategies and tools used to predict, monitor, and assess the toxicity of PRRT. The few mutations in tumour genes that can be evaluated (eg, ATM and DAXX) are limited to pancreatic NETs and are most likely not informative. Assays that are transcriptomic or based on genes are effective in the prediction of radiotherapy response in other cancers. A blood-based assay for eight genes (the PRRT prediction quotient [PPQ]) has an overall accuracy of 95% for predicting responses to PRRT in NETs. No molecular markers exist that can predict the toxicity of PRRT. Candidate molecular targets include seven single nucleotide polymorphisms (SNPs) that are susceptible to radiation. Transcriptomic evaluations of blood and a combination of gene expression and specific SNPs, assessed by machine learning with algorithms that are tumour-specific, might yield molecular tools to enhance the efficacy and safety of PRRT.

The utility of blood-based molecular tools-the NETest-to monitor and evaluate the efficacy of PRRT in neuroendocrine tumors

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Background: Peptide receptor radionuclide therapy (PRRT) is an effective therapy for metastatic/inoperable neuroendocrine tumors (NETs). Tools to predict and monitor the efficacy of therapy are important adjuncts in the radio-oncology armamentarium. Standard blood biomarkers are not effective by new molecular based assays such as the PRRT Predictive Quotient (PPQ) and NETest are effective as real-time predictors and monitors of therapy. We aimed to prospectively evaluate whether: 1) the NETest functioned as a surrogate biomarker for image-based per RECIST evaluation of PRRT efficacy; 2) there was a correlation between changes in NETest levels during therapy, PPQ prediction and treatment efficacy. Methods: Three independent 177Lu-PRRT-treated GEP-NET and BPNEN cohorts (Rotterdam, Netherlands: n= 41; Bad-Berka, Germany: n= 44; Meldola, Italy: n= 72). Treatment response: RECIST1.1 [Responder (stable, partial/complete response) vs Non-Responder]. Blood sampling: pre-PRRT, prior to each cycle and 6 months (median) after completion of all cycles. PPQ (positive/negative) and NETest (0-100 score) by PCR. Stable<40; progressive > 40). CgA (ELISA) as comparator. Samples deidentified, measurement and analyses blinded. Kaplan-Meier survival and Mann-Whitney analyses. Results: 122 of 157 were evaluable. RECIST stabilization or response in 67%; 33% progressed. NETest significantly ( p< 0.0001) decreased in RECIST-“responders” (-47±3%); in “non-responders” it elevated (+79±19%, p< 0.0005). NETest monitoring accuracy 98% (119/122). Follow-up levels > 40 (progressive) vs stable (<40) significantly correlated with mPFS (not reached vs. 10 months; HR 0.04, 95%CI: 0.02-0.07). PPQ response prediction was accurate in 118 (97%); 99% accurate positive and 93% accurate negative prediction. NETest significantly ( p< 0.0001) decreased in PPQ-predicted responders (-46±3%) and remained increased in PPQ-predicted non-responders (+75±19%). Follow-up NETest categories stable vs progressive significantly correlated with PPQ prediction and mPFS (not reached vs. 10 months; HR 0.06, 95%CI: 0.03-0.12). In comparison, the standard biomarker, CgA, failed to predict or correlate with response to PRRT ( p= NS). Conclusions: NETest accurately (98%) monitors PRRT response and is an effective surrogate marker for radiological response (image concordance 98%). A NETest decrease identified responders (99%) and correlated ( > 97%) with the pretreatment PPQ response predictor.

Prior therapies as prognostic factors of overall survival in metastatic castration-resistant prostate cancer patients treated with [177Lu]Lu-PSMA-617. A WARMTH multicenter study (the 617 trial)

Introduction

The impact of prior therapies, especially chemotherapy, on overall survival (OS) in patients with castration-resistant prostate cancer (CRPC) receiving [¹⁷⁷Lu]Lu-PSMA-617 therapy has been the subject of controversy. Therefore, WARMTH decided to plan a multicenter retrospective analysis (the “617 trial”) to evaluate response rate and OS as well as the impact of prior therapies on OS in more than 300 patients treated with ¹⁷⁷Lu-PSMA-617.

Materials and methods

The data of 631 metastatic CRPC (mCRPC) patients from 11 different clinics were evaluated. According to the inclusion and exclusion criteria, all patients had to have received at least abiraterone or enzalutamide prior to [¹⁷⁷Lu]Lu-PSMA-617 therapy. The patients were divided into three groups: patients who had received prior chemotherapy, patients who avoided chemotherapy, and patients for whom a chemotherapy was contraindicated.

Results

The analysis included the data of 416 patients, with a median age of 71.9 years. At the time of analysis, 87 patients (20,9%) were still alive. A total of 53.6% of patients had received both abiraterone and enzalutamide; 75.5% and 26.4% had a history of chemotherapy with docetaxel and cabazitaxel, respectively. A total of 20.4% had had Ra-223. The median OS was 11.1 months. Prior chemotherapy, the existence of bone and liver metastases, as well as Eastern Cooperative Oncology Group (ECOG) status, were significant prognosticators of worse overall survival in both univariate and multivariate analyses. Patients without any prior chemotherapy showed a significantly longer OS (14.6 months). The median OS in patients who received one or two lines of chemotherapy with docetaxel or docetaxel followed by cabazitaxel, respectively, was 10.9 months and 8.9 months. There was no difference in OS between patients who had not received chemotherapy and patients for whom chemotherapy was contraindicated. The other prior therapies did not have any significant impact on OS.

Conclusion

In the present multicenter analysis, chemotherapy-naïve mCRPC patients receiving [¹⁷⁷Lu]Lu-PSMA-617 therapy had a significantly longer OS than patients with a history of chemotherapy. This remained independent in the multivariate analysis besides presence of bone and liver metastases as negative prognosticators for survival, whereas an ECOG of 0–1 is associated with a longer OS.

Electronic supplementary material

The online version of this article (10.1007/s00259-020-04797-9) contains supplementary material, which is available to authorized users.

Metastatic extent predicts survival as patients with metastatic castration-resistant prostate cancer are treated with 177Lu-PSMA radioligand therapy

PSMA based radioligand is a new investigational drug for treatment of metastatic multidrug-resistant and castration-resistant prostate cancer. Prognostic factors point to above and below average overall survival (OS) after the treatment.

Kessel et al. [Theranostics 2019;9:4841-8] reported for the first time that two sites of visceral metastases, lungs and liver, differed in impact on OS after treatment with ¹⁷⁷Lu PSMA 617. Treatment with established drugs showed the same trend. The difference in OS between the sites is independent of the type of treatment and can reflect changes in tumor biology during the progression of metastatic prostate cancer.

Prognostic Value of 18F-FDG PET/CT in a Large Cohort of Patients with Advanced Metastatic Neuroendocrine Neoplasms Treated with Peptide Receptor Radionuclide Therapy

The objective of this retrospective study was to determine the role of ¹⁸F-FDG PET/CT in a large cohort of 495 patients with metastatic neuroendocrine neoplasms (NENs) who were treated with peptide receptor radionuclide therapy (PRRT) with a long-term follow-up. Methods: The 495 patients were treated with ¹⁷⁷Lu- or ⁹⁰Y-DOTATOC/DOTATATE PRRT between February 2002 and July 2018. All subjects received both ⁶⁸Ga-DOTATOC/TATE/NOC and ¹⁸F-FDG PET/CT before treatment and were followed 3-189 mo. Kaplan-Meier analysis, log-rank testing (Mantel-Cox), and Cox regression analysis were performed for overall survival (OS) and progression-free survival (PFS). Results: One hundred ninety-nine patients (40.2%) presented with pancreatic NENs, 49 with cancer of unknown primary, and 139 with midgut NENs, whereas the primary tumor was present in the rectum in 20, in the lung in 38, in the stomach in 8, and in other locations in 42. ¹⁸F-FDG PET/CT was positive in 382 (77.2%) patients and negative in 113 (22.8%) before PRRT, whereas 100% were ⁶⁸Ga-DOTATOC/TATE/NOC-positive. For all patients, the median PFS and OS, defined from the start of PRRT, were 19.6 mo and 58.7 mo, respectively. Positive ¹⁸F-FDG results predicted shorter PFS (18.5 mo vs. 24.1 mo; P = 0.0015) and OS (53.2 mo vs. 83.1 mo; P < 0.001) than negative ¹⁸F-FDG results. Among the cases of pancreatic NENs, the median OS was 52.8 mo in ¹⁸F-FDG-positive subjects and 114.3 mo in ¹⁸F-FDG-negative subjects (P = 0.0006). For all patients positive for ¹⁸F-FDG uptake, and a ratio of more than 2 for the highest SUV_max on ⁶⁸Ga-somatostatin receptor (SSTR) PET to the most ¹⁸F-FDG-avid tumor lesions, the median OS was 53.0 mo, compared with 43.4 mo in those patients with a ratio of less than 2 (P = 0.030). For patients with no ¹⁸F-FDG uptake (complete mismatch imaging pattern), the median OS was 108.3 mo versus 76.9 mo for an SUV_max of more than 15.0 and an SUV_max of 15.0 or less on ⁶⁸Ga-SSTR PET/CT, respectively. Conclusion: The presence of positive lesions on ¹⁸F-FDG PET is an independent prognostic factor in patients with NENs treated with PRRT. Metabolic imaging with ¹⁸F-FDG PET/CT complements the molecular imaging aspect of ⁶⁸Ga-SSTR PET/CT for the prognosis of survival after PRRT. High SSTR expression combined with negative ¹⁸F-FDG PET/CT results is associated with the most favorable long-term prognosis.

Impact of liver tumour burden, alkaline phosphatase elevation, and target lesion size on treatment outcomes with 177Lu-Dotatate: an analysis of the NETTER-1 study

PURPOSE

To assess the impact of baseline liver tumour burden, alkaline phosphatase (ALP) elevation, and target lesion size on treatment outcomes with ¹⁷⁷Lu-Dotatate.

METHODS

In the phase 3 NETTER-1 trial, patients with advanced, progressive midgut neuroendocrine tumours (NET) were randomised to 177Lu-Dotatate (every 8 weeks, four cycles) plus octreotide long-acting release (LAR) or to octreotide LAR 60 mg. Primary endpoint was progression-free survival (PFS). Analyses of PFS by baseline factors, including liver tumour burden, ALP elevation, and target lesion size, were performed using Kaplan-Meier estimates; hazard ratios (HRs) with corresponding 95% CIs were estimated using Cox regression.

RESULTS

Significantly prolonged median PFS occurred with ¹⁷⁷Lu-Dotatate versus octreotide LAR 60 mg in patients with low (< 25%), moderate (25-50%), and high (> 50%) liver tumour burden (HR 0.187, 0.216, 0.145), and normal or elevated ALP (HR 0.153, 0.177), and in the presence or absence of a large target lesion (diameter > 30 mm; HR, 0.213, 0.063). Within the ¹⁷⁷Lu-Dotatate arm, no significant difference in PFS was observed amongst patients with low/moderate/high liver tumour burden (P = 0.7225) or with normal/elevated baseline ALP (P = 0.3532), but absence of a large target lesion was associated with improved PFS (P = 0.0222). Grade 3 and 4 liver function abnormalities were rare and did not appear to be associated with high baseline liver tumour burden.

CONCLUSIONS

¹⁷⁷Lu-Dotatate demonstrated significant prolongation in PFS versus high-dose octreotide LAR in patients with advanced, progressive midgut NET, regardless of baseline liver tumour burden, elevated ALP, or the presence of a large target lesion. Clinicaltrials.gov : NCT01578239, EudraCT: 2011-005049-11.

PRRT neuroendocrine tumor response assessment using blood transcript analysis: The NETest

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Background: Peptide receptor radionuclide therapy (PRRT) is effective for metastatic/inoperable neuroendocrine tumors (NETs). Imaging response assessment is most effective after treatment completion. Blood biomarkers such as PRRT Predictive Quotient (PPQ) and NETest are effective in real-time. PPQ predicts PRRT efficacy, NETest monitors disease. We prospectively evaluated: 1) NETest as a surrogate biomarker for RECIST; 2) Correlation of NETest levels, PPQ prediction and treatment efficacy. Methods: Three independent 177Lu-PRRT-treated GEP-NET and BPNEN cohorts (Rotterdam, Netherlands: n=41; Bad-Berka, Germany: n=44; Meldola, Italy: n=72). Treatment response: RECIST1.1 [Responder (stable, partial/complete response) vs Non-Responder]. Blood sampling: pre-PRRT, prior to each cycle and 6 months (median) after completion of all cycles. PPQ (positive/negative) and NETest (0-100 score) by PCR. Stable<40; progressive >40). CgA (ELISA) as comparator. Samples deidentified, measurement and analyses blinded. Kaplan-Meier survival and Mann-Whitney analyses. Results: 122 of 157 were evaluable. RECIST stabilization or response in 67%; 33% progressed. NETest significantly ( p<0.0001) decreased in RECIST-“responders” (-47±3%); in “non-responders” it elevated (+79±19%, p<0.0005). NETest monitoring accuracy 98% (119/122). Follow-up levels >40 (progressive) vs stable (<40) significantly correlated with mPFS (not reached vs. 10 months; HR 0.04, 95%CI: 0.02-0.07). PPQ response prediction was accurate in 118 (97%); 99% accurate positive and 93% accurate negative prediction. NETest significantly ( p<0.0001) decreased in PPQ-predicted responders (-46±3%) and remained increased in PPQ-predicted non-responders (+75±19%). Follow-up NETest categories stable vs progressive significantly correlated with PPQ prediction and mPFS (not reached vs. 10 months; HR 0.06, 95%CI: 0.03-0.12). CgA failed to identify response to PRRT ( p=NS). Conclusions: NETest accurately (98%) monitors PRRT response and is an effective surrogate marker for radiological response (image concordance 98%). A NETest decrease identified responders and correlated (>97%) with the pretreatment PPQ response predictor.

Neuroendocrine Neoplasms of the Small Bowel and Pancreas

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

PRRT neuroendocrine tumor response monitored using circulating transcript analysis: the NETest

PURPOSE

Peptide receptor radionuclide therapy (PRRT) is effective for metastatic/inoperable neuroendocrine tumors (NETs). Imaging response assessment is usually efficient subsequent to treatment completion. Blood biomarkers such as PRRT Predictive Quotient (PPQ) and NETest are effective in real-time. PPQ predicts PRRT efficacy; NETest monitors disease. We prospectively evaluated: (1) NETest as a surrogate biomarker for RECIST; (2) the correlation of NETest levels with PPQ prediction.

METHODS

Three independent ¹⁷⁷Lu-PRRT-treated GEP-NET and lung cohorts (Meldola, Italy: n = 72; Bad-Berka, Germany: n = 44; Rotterdam, Netherlands: n = 41). Treatment response: RECIST1.1 (responder (stable, partial, and complete response) vs non-responder). Blood sampling: pre-PRRT, before each cycle and follow-up (2-12 months). PPQ (positive/negative) and NETest (0-100 score) by PCR. Stable < 40; progressive > 40). CgA (ELISA) as comparator. Samples de-identified, measurement and analyses blinded. Kaplan-Meier survival and standard statistics.

RESULTS

One hundred twenty-two of the 157 were evaluable. RECIST stabilization or response in 67%; 33% progressed. NETest significantly (p < 0.0001) decreased in RECIST "responders" (- 47 ± 3%); in "non-responders," it remained increased (+ 79 ± 19%) (p < 0.0005). NETest monitoring accuracy was 98% (119/122). Follow-up levels > 40 (progressive) vs stable (< 40) significantly correlated with mPFS (not reached vs. 10 months; HR 0.04 (95%CI, 0.02-0.07). PPQ response prediction was accurate in 118 (97%) with a 99% accurate positive and 93% accurate negative prediction. NETest significantly (p < 0.0001) decreased in PPQ-predicted responders (- 46 ± 3%) and remained elevated or increased in PPQ-predicted non-responders (+ 75 ± 19%). Follow-up NETest categories stable vs progressive significantly correlated with PPQ prediction and mPFS (not reached vs. 10 months; HR 0.06 (95%CI, 0.03-0.12). CgA did not reflect PRRT treatment: in RECIST responders decrease in 38% and in non-responders 56% (p = NS).

CONCLUSIONS

PPQ predicts PRRT response in 97%. NETest accurately monitors PRRT response and is an effective surrogate marker of PRRT radiological response. NETest decrease identified responders and correlated (> 97%) with the pretreatment PPQ response predictor. CgA was non-informative.

Preclinical investigations and first-in-human application of 152Tb-PSMA-617 for PET/CT imaging of prostate cancer

Background

For almost a decade, terbium radioisotopes have been explored for their potential theragnostic application in nuclear medicine: ¹⁵²Tb and ¹⁵⁵Tb are the radioisotopes identified for PET or SPECT imaging, while ¹⁴⁹Tb and ¹⁶¹Tb have suitable decay characteristics for α- and combined β⁻/Auger-e⁻-therapy, respectively. In the present study, the application of ¹⁵²Tb, in combination with PSMA-617 for imaging of prostate-specific membrane antigen (PSMA)-positive prostate cancer, was demonstrated in a preclinical setting and in a patient with metastatic castration-resistant prostate cancer (mCRPC).

Results

¹⁵²Tb was produced at the ISOLDE facility at CERN/Geneva, Switzerland, by spallation, followed by on-line mass separation. The chemical separation was performed at Paul Scherrer Institute using chromatographic methods, as previously reported. ¹⁵²Tb was employed for labeling PSMA-617, and the radioligand was extensively investigated in vitro to demonstrate similar characteristics to its ¹⁷⁷Lu-labeled counterpart. Preclinical PET/CT imaging studies performed with mice enabled visualization of PSMA-positive PC-3 PIP tumors, while uptake in PSMA-negative PC-3 flu tumors were absent. Based on these promising preclinical results, ¹⁵²Tb was shipped to Zentralklinik Bad Berka, Germany, where it was used for labeling of PSMA-617, enabling PET imaging of a patient with mCRPC. PET/CT scans were performed over a period of 25 h post injection (p.i.) of the radioligand (140 MBq). The images were of diagnostic quality, particularly those acquired at later time points, and enabled the detection of the same metastatic lesions and of local recurrent tumor as previously detected by ⁶⁸Ga-PSMA-11 PET/CT acquired 45 min p.i.

Conclusions

The results of this study demonstrate the successful preparation and preclinical testing of ¹⁵²Tb-PSMA-617 and its first application in a patient with mCRPC. This work could pave the way towards clinical application of other Tb radionuclides in the near future, most importantly ¹⁶¹Tb, which has promising decay characteristics for an effective treatment of mCRPC patients.

Electronic supplementary material

The online version of this article (10.1186/s13550-019-0538-1) contains supplementary material, which is available to authorized users.

From Bench to Bedside-The Bad Berka Experience With First-in-Human Studies

Precision oncology is being driven by rapid advances in novel diagnostics and therapeutic interventions, with treatments targeted to the needs of individual patients on the basis of genetic, biomarker, phenotypic, or psychosocial characteristics that distinguish a given patient from other patients with similar clinical presentations. Inherent in the theranostics paradigm is the assumption that diagnostic test results can precisely determine whether an individual is likely to benefit from a specific treatment. As part and integral in the current era of precision oncology, theranostics in the context of nuclear medicine aims to identify the appropriate molecular targets in neoplasms (diagnostic tool), so that the optimal ligands and radionuclides (therapeutic tool) with favorable labeling chemistry can be selected for personalized management of a specific disease, taking into consideration the specific patient, and subsequently monitor treatment response. Over the past two decades, the use of gallium-68 labeled peptides for somatostatin receptor (SSTR)-targeted PET/CT (or PET/MRI) imaging followed by lutetium-177 and yttrium-90 labeled SSTR-agonist for peptide receptor radionuclide therapy has demonstrated remarkable success in the management of neuroendocrine neoplasms, and paved the way to other indications of theranostics. Rapid advances are being made in the development of other peptide-based radiopharmaceuticals, small molecular-weight ligands and with newer radioisotopes with more favorable kinetics, potentially useful for theranostics strategies for the clinical application. The present review features the Bad Berka experience with first-in-human studies of new radiopharmaceuticals, for example, prostate-specific membrane antigen ligand, gastrin-releasing peptide receptor, neurotensin receptor 1 ligand, novel SSTR-targeting peptides and nonpeptide, and bone-seeking radiopharmaceuticals. Also new radioisotopes, for example, actinium (²²⁵Ac), copper (⁶⁴Cu), scandium (⁴⁴Sc), and terbium (¹⁵²Tb/¹⁶¹Tb) will be discussed briefly demonstrating the development from basic science to precision oncology in the clinical setting.

Semiquantitative Parameters in PSMA-Targeted PET Imaging with [18F]DCFPyL: Intrapatient and Interpatient Variability of Normal Organ Uptake

PURPOSE

Prostate-specific membrane antigen (PSMA)-targeted positron emission tomography (PET) imaging has impacted the management of patients with prostate cancer (PCa) in many parts of the world. PSMA-targeted endoradiotherapies are also being increasingly utilized and for these applications, the radiopharmaceutical distribution in normal organs is particularly important because it may limit the dose that can be delivered to tumors. In this study, we measured both interpatient and intrapatient variability of [¹⁸F]DCFPyL uptake in the most relevant normal organs.

PROCEDURES

Baseline and 6-month follow-up PSMA-targeted [¹⁸F]DCFPyL PET/computed tomography (CT) scans from 39 patients with PCa were reviewed. Volumes of interest were manually drawn using the best visual approximation of the organ edge for both lacrimal glands, all four major salivary glands, the liver, the spleen, and both kidneys for all patients. The average SUV_mean, the COVs, and intraclass correlation coefficients (ICCs) across scans were calculated. Bland-Altman analyses were performed for all organs to derive repeatability coefficients (RCs).

RESULTS

The liver demonstrated the lowest interpatient variability (13.0 and 16.6 % at baseline and follow-up, respectively), while the spleen demonstrated the largest interpatient variability (44.6 and 51.0 % at baseline and follow-up, respectively). The lowest intrapatient variability was found in the spleen (ICC 0.86) while the highest intrapatient variability was in the kidneys (ICCs 0.40-0.50). Bland-Altman analyses showed 95 % repeatability coefficients for mean uptake > 40 % for multiple organs and were highest for the lacrimal glands, kidneys, and spleen.

CONCLUSIONS

Normal organs demonstrate significant variability in uptake of the PSMA-targeted radiotracer [¹⁸F]DCFPyL. Depending on the organ, different contributions of interpatient and intrapatient factors affect the intrinsic variability. The RCs also vary significantly among the different organs were highest for the lacrimal glands, kidneys, and spleen. These findings may have important implications for the design of clinical protocols and personalized dosimetry for PSMA-targeted endoradiotherapies.

Instant kit preparation of 68Ga-radiopharmaceuticals via the hybrid chelator DATA: clinical translation of [68Ga]Ga-DATA-TOC

Purpose

The widespread use of ⁶⁸Ga for positron emission tomography (PET) relies on the development of radiopharmaceutical precursors that can be radiolabelled and dispensed in a simple, quick, and convenient manner. The DATA (6-amino-1,4-diazapine-triacetate) scaffold represents a novel hybrid chelator architecture possessing both cyclic and acyclic character that may allow for facile access to ⁶⁸Ga-labelled tracers in the clinic. We report the first bifunctional DATA chelator conjugated to [Tyr³]octreotide (TOC), a somatostatin subtype 2 receptor (SST₂)-targeting vector for imaging and functional characterisation of SSTR₂ expressing tumours.

Methods

The radiopharmaceutical precursor, DATA-TOC, was synthesised as previously described and used to complex ^natGa(III) and ⁶⁸Ga(III). Competition binding assays of [^natGa]Ga-DATA-TOC or [^natGa]Ga-DOTA-TOC against [¹²⁵I-Tyr²⁵]LTT-SS28 were conducted in membranes of HEK293 cells transfected to stably express one of the hSST_2,3,5 receptor subtypes (HEK293-hSST_2/3/5 cells). First in vivo studies were performed in female NMRI-nude mice bearing SST₂-positive mouse phaeochromocytoma mCherry (MPC-mCherry) tumours to compare the in vivo SST₂-specific tumour-targeting of [⁶⁸Ga]Ga-DATA-TOC and its overall pharmacokinetics versus the [⁶⁸Ga]Ga-DOTA-TOC reference. A direct comparison of [⁶⁸Ga]Ga-DATA-TOC with the well-established PET radiotracer [⁶⁸Ga]Ga-DOTA-TOC was additionally performed in a 46-year-old male patient with a well-differentiated NET (neuroendocrine tumour), representing the first in human administration of [⁶⁸Ga]Ga-DATA-TOC.

Results

DATA-TOC was labelled with ⁶⁸Ga with a radiolabelling efficiency of > 95% in less than 10 min at ambient temperature. A molar activity up to 35 MBq/nmol was achieved. The hSST₂-affinities of [^natGa]Ga-DATA-TOC and [^natGa]Ga-DOTA-TOC were found similar with only sub-nanomolar differences in the respective IC₅₀ values. In mice, [⁶⁸Ga]Ga-DATA-TOC was able to visualise the tumour lesions, showing standardised uptake values (SUVs) similar to [⁶⁸Ga]Ga-DOTA-TOC. Direct comparison of the two PET tracers in a NET patient revealed very similar tumour uptake for the two ⁶⁸Ga-radiotracers, but with a higher tumour-to-liver contrast for [⁶⁸Ga]Ga-DATA-TOC.

Conclusion

[⁶⁸Ga]Ga-DATA-TOC was prepared, to a quality appropriate for in vivo use, following a highly efficient kit type process. Furthermore, the novel radiopharmaceutical was comparable or better than [⁶⁸Ga]Ga-DOTA-TOC in all preclinical tests, achieving a higher tumour-to-liver contrast in a NET-patient. The results illustrate the potential of the DATA-chelator to facilitate the access to and preparation of ⁶⁸Ga-radiotracers in a routine clinical radiopharmacy setting.

Electronic supplementary material

The online version of this article (10.1186/s13550-019-0516-7) contains supplementary material, which is available to authorized users.

Analysis of patient diaries in the NETTER-1 Study of 177Lu-DOTATATE versus high-dose octreotide in progressive midgut neuroendocrine tumors

4111

Background: The primary statistical analysis for the NETTER-1 trial showed a clinically and statistically significant PFS benefit with 177Lu-DOTATATE vs. high-dose octreotide. 177Lu-DOTATATE treatment was also correlated with a significant delay in time to deterioration in HRQoL. In addition to HRQoL questionnaires, patients were asked to record presence or absence of a range of symptoms in a daily diary. Methods: A Mixed Model Repeated Measures (MMRM) was used to analyze the change, compared to baseline, of the occurrence of abdominal Pain, diarrhea and cutaneous flushing as these symptoms were regarded as the most relevant to judge the overall disease status. For each visit (week = 0, 4, 8, etc.) the number of days with symptoms during the previous period was calculated. At baseline, the number of days with symptoms was counted over the previous 6 weeks, whereas the time frame between visits lasted 4 weeks. Results: The estimated number of days with symptoms declined significantly more in the 177Lu-dotatate arm compared to the octreotide arm. The difference in change and the confidence intervals for the symptoms abdominal pain, diarrhea and flushing of skin are, respectively: -3.11 [-4.88; -1.34], -3.11 [-5.04; -1.18] and -1.98 [-3.88; -0.08]. Conclusions: Analysis of symptom diaries confirms that 177Lu-Dotatate can palliate clinically relevant symptoms when compared to high-dose octreotide.

Surgery and peptide receptor radionuclide therapy: An effective multimodal approach for metastatic neuroendocrine tumors

4113

Background: Neuroendocrine neoplasia (NEN) of the pancreas (PanNEN) or small bowel (SBNEN) frequently present with metastases at initial diagnosis, undermining the efficacy of surgical treatment. Peptide receptor radionuclide therapy (PRRT) with radiolabelled somatostatin analogues, 90Y-DOTATOC and 177Lu-DOTATATE, has been shown to achieve prolonged progression-free survival (PFS) and overall survival (OS) in a substantial number of non-surgical patients with advanced NEN. Our aim was to prospectively determine the efficacy of a combination of radical loco-regional surgery and 177Lu PRRT in patients with metastasised NEN. Methods: A set of inclusion criteria was defined (e.g. PanNEN or SBNEN, G1/G2 NEN, initial tumour diagnosis, treatment naïve patient, stage IV NEN, positivity on 68Ga DOTATATE or DOTATOC PET/CT, eligibility for surgery and PRRT). Patients underwent PRRT within 3 months following surgery. Follow-up included biochemistry and imaging. Outcome measures included 1-, 3-, and 5-year OS and PFS from initial diagnosis. Results: Forty-one patients met eligibility criteria and were included. There were 26 males (63.4%) and median age at surgery was 58.8 years (range 32.1-78.3). All patients with SBNEN underwent right hemicolectomy, terminal ileal resection and mesenteric lympadenectomy. In PanNEN patients either Whipple procedure or distal pancreatectomy and peripancreatic lymphadenectomy were performed. The median number of PRRT cycles was 4 (range 2-6). Post-treatment mortality was 0%. Surgical morbidity was 12% (all grade 1 according Clavien-Dindo) and transient grade 1 toxicity occurred post PRRT in 40%. There was no grade 3 toxicity. Median follow-up was 5.48 years (range 0.53 – 11.98). Median PFS and OS were 3.33 years and 9.07 years, respectively. Progression-free survival (with 95% CI) was at 1-, 3-, and 5-years 80% (68.7-92.6), 60.9% (45.9-75.9) and 43.3% (27.4-59.3), respectively. Overall survival (with 95% CI) at 1-, 3-, and 5-years was 97.6% (93-100), 97.6% (93-100), and 95% (87-100), respectively. Conclusions: Radical loco-regional surgery for primary tumours combined with PRRT provides a novel, highly efficacious approach in metastasised NEN.

Efficacy of Detoxsan® powder on diarrhea caused by gastrointestinal neuroendocrine tumors

BACKGROUND

Patients with neuroendocrine tumors (NETs) of the gastrointestinal tract suffer frequently from chronic diarrhea. A well characterized medical advice containing zeolite (Detoxsan^® powder) was applied to patients suffered from therapy-refractory diarrhea either by its frequency or by watery stool, despite receiving standard pharmacotherapy according to the guidelines for carcinoid syndrome and comorbidities. Detoxsan^® powder acts as an adsorbent and might reduce significantly symptoms of diarrhea in patients suffering from NETs.

AIM

To overcome the therapy-refractory diarrhea of patients with NETs by the zeolite containing medical advice Detoxsan^® powder.

METHODS

A total of 20 patients (12 female and 8 male) suffering from diarrhea either by its frequency or from watery stool caused by NETs were included. In each patient, the diagnosis had been confirmed by histology and somatostatin receptors expression proven by positron emission tomography/computed tomography using Ga-68-labeled somatostatin analogs. All patients received standard-of-care pharmacotherapy and were additionally given Detoxsan^® powder as an extemporaneous drug containing 90% natural Cuban zeolite and 10% magnesium aspartate. Recommended daily dosage ranges between 3 g once to three times per day. Each day dose and bowel movements were documented by the patients themselves in a pre-defined table. Additionally to the bowel movements quantitative determinations of serotonin, urea, creatinine and single ions were performed within the serum of the patients by commercially available equipment used as a matter of routine in the clinic.

RESULTS

All patients enrolled in this pilot study did not only suffer from NETs, but also from comorbidities and treatment-resistant diarrhea. There was insufficient control of diarrhea, most probably due to the secretion of hormones like serotonin produced by the slowly growing and highly differentiated NETs. All patients only took Detoxsan^® powder as an antidiarrheal drug. In general, response effects need several days to become perceptible and require an intake of Detoxsan^® powder for an extended time period or intermittently, if persisting stabilization of bowel movements could not be achieved. A correlation between NET grade, part and size of bowel resection and functionality of the tumor could not be demonstrated. Therefore, diarrhea seemed to be based on the metabolic activity of the well-differentiated NETs, which eventually led to treatment resistance. In summary, 14 out of the 20 patients (70%) declared to be very content with using Detoxsan^® powder and observed a significant reduction of diarrhea, while the effective dose and intake period that resulted in a symptom relief varied individually.

CONCLUSION

Detoxsan^® powder is able to reduce significantly symptoms of NET-related diarrhea in the majority of patients. The duration of taking Detoxsan^® powder and its dosage vary individually.