Diagnosis of Prostate Cancer with a Neurotensin-Bombesin Radioligand Combination-First Preclinical Results.

The concept of radiotheranostics relies on the overexpression of a biomolecular target on malignant cells to direct diagnostic/therapeutic radionuclide-carriers specifically to cancer lesions. The concomitant expression of more than one target in pathological lesions may be elegantly exploited to improve diagnostic sensitivity and therapeutic efficacy. Toward this goal, we explored a first example of a combined application of [Tc]Tc-DT11 (DT11, N-Lys(MPBA-PEG4)-Arg-Arg-Pro-Tyr-Ile-Leu-OH; NTSR-specific) and [Tc]Tc-DB7(DB7, N-PEG2-DPhe-Gln-Trp-Ala-Val-Gly-His-Leu-NHEt; GRPR-specific) in prostate cancer models.

Bis(Disulfide)-Bridged Somatostatin-14 Analogs and Their [In]In-Radioligands: Synthesis and Preclinical Profile.

The overexpression of one or more somatostatin receptors (SSTR) in human tumors has provided an opportunity for diagnosis and therapy with somatostatin-like radionuclide carriers. The application of "pansomatostatin" analogs is expected to broaden the clinical indications and upgrade the diagnostic/therapeutic efficacy of currently applied SSTR-prefering radioligands. In pursuit of this goal, we now introduce two bicyclic somatostatin-14 (SS14) analogs, AT5S (DOTA-Ala-Gly-c[Cys-Lys-Asn-c[Cys-Phe-DTrp-Lys-Thr-Cys]-Thr-Ser-Cys]) and AT6S (DOTA-Ala-Gly-c[Cys-Lys-c[Cys-Phe-Phe-DTrp-Lys-Thr-Phe-Cys]-Ser-Cys]), suitable for labeling with trivalent radiometals and designed to sustain in vivo degradation.

Side-Chain Modified [Tc]Tc-DT1 Mimics: A Comparative Study in NTSR-Positive Models.

Radiolabeled neurotensin analogs have been developed as candidates for theranostic use against neurotensin subtype 1 receptor (NTSR)-expressing cancer. However, their fast degradation by two major peptidases, neprilysin (NEP) and angiotensin-converting enzyme (ACE), has hitherto limited clinical success. We have recently shown that palmitoylation at the -amine of Lys in [Tc]Tc-[Lys]DT1 (DT1, N-Gly-Arg-Arg-Pro-Tyr-Ile-Leu-OH, N = 6-(carboxy)-1,4,8,11-tetraazaundecane) led to the fully stabilized [Tc]Tc-DT9 analog, displaying high uptake in human pancreatic cancer AsPC-1 xenografts but unfavorable pharmacokinetics in mice.

Toward Stability Enhancement of NTSR-Targeted Radioligands: Structural Interventions on [Tc]Tc-DT1.

The neurotensin subtype 1 receptor (NTSR) is overexpressed in a number of human tumors, thereby representing a valid target for cancer theranostics with radiolabeled neurotensin (NT) analogs like [Tc]Tc-DT1 (DT1, N-Gly-NT(8-13)). Thus far, the fast degradation of intravenously injected NT-radioligands by neprilysin (NEP) and angiotensin-converting enzyme (ACE) has compromised their clinical applicability. Aiming at metabolic stability enhancements, we herein introduce (i) DT7 ([DAsn]DT1) and (ii) DT8 ([β-Homoleucine]DT1), modified at the C-terminus, along with (iii) DT9 ([(palmitoyl)Lys]DT1), carrying an albumin-binding domain (ABD) at Lys.

Nonpeptidic Z360-Analogs Tagged with Trivalent Radiometals as Anti-CCKR Cancer Theranostic Agents: A Preclinical Study.

(1) Background: Theranostic approaches in the management of cholecystokinin subtype 2 receptor (CCKR)-positive tumors include radiolabeled gastrin and CCK motifs. Moving toward antagonist-based CCKR-radioligands instead, we herein present three analogs of the nonpeptidic CCKR-antagonist Z360, GAS1/2/3. Each was conjugated to a different chelator (DOTA, NODAGA or DOTAGA) for labeling with medically relevant trivalent radiometals (e.

Lu-Dotatate plus long-acting octreotide versus high‑dose long-acting octreotide in patients with midgut neuroendocrine tumours (NETTER-1): final overall survival and long-term safety results from an open-label, randomised, controlled, phase 3 trial.

Background: The primary analysis of the phase 3 NETTER-1 trial showed significant improvement in progression-free survival with Lu-Dotatate plus long-acting octreotide versus high-dose long-acting octreotide alone in patients with advanced midgut neuroendocrine tumours. Here, we report the prespecified final analysis of overall survival and long-term safety results.

Methods: This open-label, randomised, phase 3 trial enrolled patients from 41 sites in eight countries across Europe and the USA.

A novel definition and treatment of hyperinflammation in COVID-19 based on purinergic signalling.

Hyperinflammation plays an important role in severe and critical COVID-19. Using inconsistent criteria, many researchers define hyperinflammation as a form of very severe inflammation with cytokine storm. Therefore, COVID-19 patients are treated with anti-inflammatory drugs.

ENETS standardized (synoptic) reporting for molecular imaging studies in neuroendocrine tumours.

The European Neuroendocrine Tumor Society (ENETS) promotes practices and procedures that aim to improve the standard of care delivered to patients diagnosed with or suspected of having neuroendocrine neoplasia (NEN). At its annual Scientific Advisory Board Meeting in 2018, experts in imaging, pathology and clinical care of patients with NEN drafted guidance for the standardised reporting of diagnostic studies critical to the diagnosis, grading, staging and treatment of NEN. These included pathology, radiology, endoscopy and molecular imaging procedures.

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

We report the impact of Lu DOTATATE treatment on abdominal pain, diarrhea, and flushing, symptoms that patients with advanced midgut neuroendocrine tumors (NETs) often find burdensome. All patients enrolled in the international randomized phase 3 Neuroendocrine Tumors Therapy (NETTER-1) trial (Lu-DOTATATE plus standard-dose octreotide long-acting repeatable [LAR], = 117; high-dose octreotide LAR, = 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.

One Step Closer to Clinical Translation: Enhanced Tumor Targeting of [Tc]Tc-DB4 and [In]In-SG4 in Mice Treated with Entresto.

Background: Peptide radioligands may serve as radionuclide carriers to tumor sites overexpressing their cognate receptor for diagnostic or therapeutic purposes. Treatment of mice with the neprilysin (NEP)-inhibitor phosphoramidon was previously shown to improve the metabolic stability and tumor uptake of biodegradable radiopeptides. Aiming to clinical translation of this methodology, we herein investigated the impact of the approved pill Entresto, releasing the potent NEP-inhibitor LBQ657 in vivo, on the stability and tumor uptake of two radiopeptides.

Optimizing the Profile of [Tc]Tc-NT(7-13) Tracers in Pancreatic Cancer Models by Means of Protease Inhibitors.

Background: The overexpression of neurotensin subtype 1 receptors (NTS1Rs) in human tumors may be elegantly exploited for directing neurotensin (NT)-based radionuclide carriers specifically to cancer sites for theranostic purposes. We have recently shown that [Tc]Tc-DT1 ([Tc]Tc-[N-Gly]NT(7-13)) and [Tc]Tc-DT5 ([Tc]Tc-[N-Ala,Dab]NT(7-13)) show notably improved uptake in human colon adenocarcinoma WiDr xenografts in mice treated with neprilysin (NEP) inhibitors and/or angiotensin-converting enzyme (ACE) inhibitors compared with untreated controls. Aiming toward translation of this promising approach in NTS1R-positive pancreatic ductal adenocarcinoma (PDAC) patients, we now report on the impact of registered NEP/ACE inhibitors on the performance of [Tc]Tc-DT1 and [Tc]Tc-DT5 in pancreatic cancer models.

[Tc]Tc-DB1 Mimics with Different-Length PEG Spacers: Preclinical Comparison in GRPR-Positive Models.

: The frequent overexpression of gastrin-releasing peptide receptors (GRPRs) in human cancers provides the rationale for delivering clinically useful radionuclides to tumor sites using peptide carriers. Radiolabeled GRPR antagonists, besides being safer for human use, have often shown higher tumor uptake and faster background clearance than agonists. We herein compared the biological profiles of the GRPR-antagonist-based radiotracers [Tc]Tc-[N-PEGx-DPhe,Leu-NHEt]BBN(6-13) (N: 6-(carboxy)-1,4,8,11-tetraazaundecane; PEG: polyethyleneglycol): (i) [Tc]Tc-DB7 (x = 2), (ii) [Tc]Tc-DB13 (x = 3), and (iii) [Tc]Tc-DB14 (x = 4), in GRPR-positive cells and animal models.

Key-Protease Inhibition Regimens Promote Tumor Targeting of Neurotensin Radioligands.

Neurotensin subtype 1 receptors (NTS1R) represent attractive molecular targets for directing radiolabeled neurotensin (NT) analogs to tumor lesions for diagnostic and therapeutic purposes. This approach has been largely undermined by the rapid in vivo degradation of linear NT-based radioligands. Herein, we aim to increase the tumor targeting of three Tc-labeled NT analogs by the in-situ inhibition of two key proteases involved in their catabolism.

Impact of liver tumour burden, alkaline phosphatase elevation, and target lesion size on treatment outcomes with Lu-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 Lu-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).

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.

Comparative evaluation of the new GRPR-antagonist In-SB9 and In-AMBA in prostate cancer models: Implications of in vivo stability.

Gastrin-releasing peptide receptors (GRPRs) are overexpressed in prostate cancer, representing attractive targets for diagnosis and therapy with bombesin (BBN)-like radioligands. GRPR-antagonists have lately attracted much attention owing to inherent biosafety and favorable pharmacokinetics. We herein present the GRPR-antagonist SB9 structurally resembling the known BBN-based agonist AMBA (SB9 = [Leu NHEt-desMet ]AMBA).

Localization of Tc-GRP Analogs in GRPR-Expressing Tumors: Effects of Peptide Length and Neprilysin Inhibition on Biological Responses.

The overexpression of gastrin-releasing peptide receptors (GRPRs) in frequently occurring human tumors has provided the opportunity to use bombesin (BBN) analogs as radionuclide carriers to cancer sites for diagnostic and therapeutic purposes. We have been alternatively exploring human GRP motifs of higher GRPR selectivity compared to frog BBN sequences aiming to improve pharmacokinetic profiles. In the present study, we compared two differently truncated human endogenous GRP motifs: GRP(14⁻27) and GRP(18⁻27).

Comparing Gly/dAla-Replacement vs. the in-Situ Neprilysin-Inhibition Approach on the Tumor-targeting Efficacy of the In-SB3/In-SB4 Radiotracer Pair.

: The GRPR-antagonist Ga-SB3 visualized prostate cancer lesions in animal models and in patients. Switching radiometal from Ga to In impaired tumor targeting in mice, but coinjection of the neprilysin (NEP)-inhibitor phosphoramidon (PA) stabilized In-SB3 in circulation and remarkably increased tumor uptake. We herein report on the biological profile of In-SB4: In-[dAla]SB3.

Unmet Medical Needs in Metastatic Lung and Digestive Neuroendocrine Neoplasms.

Unmet medical needs are not infrequent in oncology, and these needs are usually of higher magnitude in rare cancers. The field of neuroendocrine neoplasms (NENs) has evolved rapidly during the last decade, and, currently, a new WHO classification is being implemented and several treatment options are available in the metastatic setting after the results of prospective phase III clinical trials. However, several questions are still unanswered, and decisions in our daily clinical practice should be made with limited evidence.

Health-Related Quality of Life in Patients With Progressive Midgut Neuroendocrine Tumors Treated With Lu-Dotatate in the Phase III NETTER-1 Trial.

Purpose Neuroendocrine tumor (NET) progression is associated with deterioration in quality of life (QoL). We assessed the impact of Lu-Dotatate treatment on time to deterioration in health-related QoL. Methods The NETTER-1 trial is an international phase III study in patients with midgut NETs.

Radiometal-Dependent Biological Profile of the Radiolabeled Gastrin-Releasing Peptide Receptor Antagonist SB3 in Cancer Theranostics: Metabolic and Biodistribution Patterns Defined by Neprilysin.

Recent advances in oncology involve the use of diagnostic/therapeutic radionuclide-carrier pairs that target cancer cells, offering exciting opportunities for personalized patient treatment. Theranostic gastrin-releasing peptide receptor (GRPR)-directed radiopeptides have been proposed for the management of GRPR-expressing prostate and breast cancers. We have recently introduced the PET tracer Ga-SB3 (SB3, DOTA- p-aminomethylaniline-diglycolic acid-DPhe-Gln-Trp-Ala-Val-Gly-His-Leu-NHEt), a receptor-radioantagonist that enables the visualization of GRPR-positive lesions in humans.

PRRT genomic signature in blood for prediction of Lu-octreotate efficacy.

Background: Peptide receptor radionuclide therapy (PRRT) utilizes somatostatin receptor (SSR) overexpression on neuroendocrine tumors (NET) to deliver targeted radiotherapy. Intensity of uptake at imaging is considered related to efficacy but has low sensitivity. A pretreatment strategy to determine individual PRRT response remains a key unmet need.

Clinical History of the Theranostic Radionuclide Approach to Neuroendocrine Tumors and Other Types of Cancer: Historical Review Based on an Interview of Eric P. Krenning by Rachel Levine.

In nuclear medicine, the term describes the combination of therapy and diagnostic imaging. In practice, this concept dates back more than 50 years; however, among the most successful examples of theranostics are peptide receptor scintigraphy and peptide receptor radionuclide therapy of neuroendocrine tumors. The development of these modalities through the radiolabeling of somatostatin analogs with various radionuclides has led to a revolution in patient management and established a foundation for expansion of the theranostic principle into other oncology indications.

Persistent Hematologic Dysfunction after Peptide Receptor Radionuclide Therapy with Lu-DOTATATE: Incidence, Course, and Predicting Factors in Patients with Gastroenteropancreatic Neuroendocrine Tumors.

Peptide receptor radionuclide therapy (PRRT) may induce long-term toxicity to the bone marrow (BM). The aim of this study was to analyze persistent hematologic dysfunction (PHD) after PRRT with Lu-DOTATATE in patients with gastroenteropancreatic neuroendocrine tumors (GEP NETs). The incidence and course of PHD were analyzed in 274 GEP NET patients from a group of 367 patients with somatostatin receptor-positive tumors.

Long-Term Efficacy, Survival, and Safety of [Lu-DOTA,Tyr]octreotate in Patients with Gastroenteropancreatic and Bronchial Neuroendocrine Tumors.

Bronchial and gastroenteropancreatic neuroendocrine tumors (NET) are slow-growing tumors, which frequently express somatostatin receptors on their cell membranes. These receptors are targets for therapy with Lutetium-177-labeled somatostatin analogues. We have treated over 1,200 patients with peptide receptor radionuclide therapy (PRRT) with [Lu-DOTA,Tyr]octreotate (Lu-DOTATATE) since the year 2000 and present the results on efficacy, survival, and toxicity of this therapy.