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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.

PurposeTo assess the impact of baseline liver tumour burden, alkaline phosphatase (ALP) elevation, and target lesion size on treatment outcomes with 177Lu-Dotatate.MethodsIn 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.ResultsSignificantly prolonged median PFS occurred with 177Lu-Dotatate versus octreotide LAR 60 mg in patients with low ( 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.Conclusions177Lu-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.

Purpose Neuroendocrine tumor (NET) progression is associated with deterioration in quality of life (QoL). We assessed the impact of 177Lu-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. Patients were randomly assigned to treatment with 177Lu-Dotatate versus high-dose octreotide. European Organisation for Research and Treatment of Cancer quality-of-life questionnaires QLQ C-30 and G.I.NET-21 were assessed during the trial to determine the impact of treatment on health-related QoL. Patients completed the questionnaires at baseline and every 12 weeks until tumor progression. QoL scores were converted to a 100-point scale according to European Organisation for Research and Treatment of Cancer instructions, and individual changes from baseline scores were assessed. Time to QoL deterioration (TTD) was defined as the time from random assignment to the first QoL deterioration ≥ 10 points for each patient in the corresponding domain scale. All analyses were conducted on the intention-to-treat population. Patients with no deterioration were censored at the last QoL assessment date. Results TTD was significantly longer in the 177Lu-Dotatate arm (n = 117) versus the control arm (n = 114) for the following domains: global health status (hazard ratio [HR], 0.406), physical functioning (HR, 0.518), role functioning (HR, 0.580), fatigue (HR, 0.621), pain (HR, 0.566), diarrhea (HR, 0.473), disease-related worries (HR, 0.572), and body image (HR, 0.425). Differences in median TTD were clinically significant in several domains: 28.8 months versus 6.1 months for global health status, and 25.2 months versus 11.5 months for physical functioning. Conclusion This analysis from the NETTER-1 phase III study demonstrates that, in addition to improving progression-free survival, 177Lu-Dotatate provides a significant QoL benefit for patients with progressive midgut NETs compared with high-dose octreotide.

Background: 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 [99mTc]Tc-DT11 (DT11, N4-Lys(MPBA-PEG4)-Arg-Arg-Pro-Tyr-Ile-Leu-OH; NTS1R-specific) and [99mTc]Tc-DB7(DB7, N4-PEG2-DPhe-Gln-Trp-Ala-Val-Gly-His-Leu-NHEt; GRPR-specific) in prostate cancer models. Methods: Accordingly, the behavior of [99mTc]Tc-DT11 was compared with that of the [99mTc]Tc-DT11+[99mTc]Tc-DB7 mixture in prostate adenocarcinoma PC-3 cells and xenografts in mice. The impact of stabilizing both radiotracers by Entresto®, as a source of the potent neprilysin inhibitor sacubitrilat, was also investigated. Results: The PC-3 cell binding of the [99mTc]Tc-DT11+[99mTc]Tc-DB7 mixture surpassed that of [99mTc]Tc-DT11. Likewise, the PC-3 tumor uptake of the [99mTc]Tc-DT11+[99mTc]Tc-DB7 mixture at 4 h post-injection was superior (7.70 ± 0.89%IA/g) compared with [99mTc]Tc-DT11 (4.23 ± 0.58%IA/g; p < 0.0001). Treatment with Entresto® led to further enhancement of the tumor uptake (to 11.57 ± 1.92%IA/g; p < 0.0001). Conclusions: In conclusion, this first preclinical study on prostate cancer models revealed clear advantages of dual NTS1R/GRPR targeting, justifying further assessment of this promising concept in other cancer models. [ABSTRACT FROM AUTHOR]

The overexpression of one or more somatostatin receptors (SST1–5R) 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 SST2R-prefering radioligands. In pursuit of this goal, we now introduce two bicyclic somatostatin-14 (SS14) analogs, AT5S (DOTA-Ala1-Gly2-c[Cys3-Lys4-Asn5-c[Cys6-Phe7-DTrp8-Lys9-Thr10-Cys11]-Thr12-Ser13-Cys14]) and AT6S (DOTA-Ala1-Gly2-c[Cys3-Lys4-c[Cys5-Phe6-Phe7-DTrp8-Lys9-Thr10-Phe11-Cys12]-Ser13-Cys14]), suitable for labeling with trivalent radiometals and designed to sustain in vivo degradation. Both AT5S and AT6S and the respective [111In]In-AT5S and [111In]In-AT6S were evaluated in a series of in vitro assays, while radioligand stability and biodistribution were studied in mice. The 8/12-mer bicyclic AT6S showed expanded affinity for all SST1–5R and agonistic properties at the SST2R, whereas AT5S lost all affinity to SST1–5R. Both [111In]In-AT5S and [111In]In-AT6S remained stable in the peripheral blood of mice, while [111In]In-AT6S displayed low, but specific uptake in AR4-2J tumors and higher uptake in HEK293-SST3R tumors in mice. In summary, high radioligand stability was acquired by the two disulfide bridges introduced into the SS14 motif, but only the 8/12-mer ring AT6S retained a pansomatostatin profile. In consequence, [111In]In-AT6S targeted SST2R-/SST3R-positive xenografts in mice. These results call for further research on pansomatostatin-like radioligands for cancer theranostics. [ABSTRACT FROM AUTHOR]

Radiolabeled neurotensin analogs have been developed as candidates for theranostic use against neurotensin subtype 1 receptor (NTS1R)-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 ε-amine of Lys7 in [99mTc]Tc-[Lys7]DT1 (DT1, N4-Gly-Arg-Arg-Pro-Tyr-Ile-Leu-OH, N4 = 6-(carboxy)-1,4,8,11-tetraazaundecane) led to the fully stabilized [99mTc]Tc-DT9 analog, displaying high uptake in human pancreatic cancer AsPC-1 xenografts but unfavorable pharmacokinetics in mice. Aiming to improve the in vivo stability of [99mTc]Tc-DT1 without compromising pharmacokinetics, we now introduce three new [99mTc]Tc-DT1 mimics, carrying different pendant groups at the ε-amine of Lys7: MPBA (4-(4-methylphenyl)butyric acid)—[99mTc]Tc-DT10; MPBA via a PEG4-linker—[99mTc]Tc-DT11; or a hydrophilic PEG6 chain—[99mTc]Tc-DT12. The impact of these modifications on receptor affinity and internalization was studied in NTS1R-positive cells. The effects on stability and AsPC-1 tumor uptake were assessed in mice without or during NEP/ACE inhibition. Unlike [99mTc]Tc-DT10, the longer-chain modified [99mTc]Tc-DT11 and [99mTc]Tc-DT12 were significantly stabilized in vivo, resulting in markedly improved tumor uptake compared to [99mTc]Tc-DT1. [99mTc]Tc-DT11 was found to achieve the highest AsPC-1 tumor values and good pharmacokinetics, either without or during NEP inhibition, qualifying for further validation in patients with NTS1R-positive tumors using SPECT/CT. [ABSTRACT FROM AUTHOR]

The neurotensin subtype 1 receptor (NTS1R) is overexpressed in a number of human tumors, thereby representing a valid target for cancer theranostics with radiolabeled neurotensin (NT) analogs like [99mTc]Tc-DT1 (DT1, N4-Gly7-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 ([DAsn14]DT1) and (ii) DT8 ([β-Homoleucine13]DT1), modified at the C-terminus, along with (iii) DT9 ([(palmitoyl)Lys7]DT1), carrying an albumin-binding domain (ABD) at Lys7. The biological profiles of the new [99mTc]Tc–radioligands were compared with [99mTc]Tc-DT1, using NTS1R-expressing AsPC-1 cells and mice models without or during NEP/ACE inhibition. The radioligands showed enhanced in vivo stability vs. [99mTc]Tc-DT1, with [99mTc]Tc-DT9 displaying full resistance to both peptidases. Furthermore, [99mTc]Tc-DT9 achieved the highest cell internalization and tumor uptake even without NEP/ACE-inhibition but with unfavorably high background radioactivity levels. Hence, unlike C-terminal modification, the introduction of a pendant ABD group in the linker turned out to be the most promising strategy toward metabolic stability, cell uptake, and tumor accumulation of [99mTc]Tc-DT1 mimics. To improve the observed suboptimal pharmacokinetics of [99mTc]Tc-DT9, the replacement of palmitoyl on Lys7 by other ABD groups is currently being pursued. [ABSTRACT FROM AUTHOR]