Strategies Towards Improving Clinical Outcomes of Peptide Receptor Radionuclide Therapy.

PURPOSE OF REVIEW: Peptide receptor radionuclide therapy (PRRT) with [177Lu-DOTA0,Tyr3] octreotate is an effective and safe second- or third-line treatment option for patients with low-grade advanced gastroenteropancreatic (GEP) neuroendocrine neoplasms (NEN). In this review, we will focus on possible extensions of the current use of PRRT and on new approaches which could further improve its treatment efficacy and safety. RECENT FINDINGS: Promising results were published regarding PRRT in other NENs, including lung NENs or high-grade NENs, and applying PRRT as neoadjuvant or salvage therapy. Furthermore, a diversity of strategic approaches, including dosimetry, somatostatin receptor antagonists, somatostatin receptor upregulation, radiosensitization, different radionuclides, albumin binding, alternative renal protection, and liver-directed therapy in combination with PRRT, have the potential to improve the outcome of PRRT. Also, novel biomarkers are presented that could predict response to PRRT. Multiple preclinical and early clinical studies have shown encouraging potential to advance the clinical outcome of PRRT in NEN patients. However, at this moment, most of these strategies have not yet reached the clinical setting of randomized phase III trials.

Salvage peptide receptor radionuclide therapy with [177Lu-DOTA,Tyr3]octreotate in patients with bronchial and gastroenteropancreatic neuroendocrine tumours.

PURPOSE: Therapy with [177Lu-DOTA,Tyr3]octreotate is effective in patients with grade I/II metastasized and/or inoperable bronchial neuroendocrine tumour (NET) or gastroenteropancreatic NET (GEP-NET). In this study, we investigated the efficacy and safety of salvage treatment with [177Lu-DOTA,Tyr3]octreotate. METHODS: Patients with progressive bronchial NET or GEP-NET were selected for re-(re)treatment if they had benefited from initial peptide receptor radionuclide therapy (I-PRRT) with a minimal progression-free survival (PFS) of 18 months. Patients received an additional cumulative dose of 14.8 GBq of [177Lu-DOTA,Tyr3]octreotate over two cycles per retreatment with PRRT (R-PRRT) or re-retreatment with PRRT (RR-PRRT). RESULTS: The safety and efficacy analyses included 181 patients and 168 patients, respectively, with bronchial NET or GEP-NET. Overall median follow-up was 88.6 months (95% CI 79.0-98.2). Median cumulative doses were 44.7 GBq (range 26.3-46.4 GBq) during R-PRRT (168 patients) and 59.7 GBq (range 55.2-≤60.5 GBq) during RR-PRRT (13 patients). Objective response and stable disease, as best response, were observed in 26 patients (15.5%) and 100 patients (59.5%) following R-PRRT, and in 5 patients (38.5%) and 7 patients (53.8%) following RR-PRRT, respectively. Median PFS was 14.6 months (95% CI 12.4-16.9) following R-PRRT and 14.2 months (95% CI 9.8-18.5) following RR-PRRT. Combined overall survival (OS) after I-PRRT plus R-PRRT and RR-PRRT was 80.8 months (95% CI 66.0-95.6). Grade III/IV bone marrow toxicity occurred in 6.6% and 7.7% of patients after R-PRRT and RR-PRRT, respectively. Salvage therapy resulted in a significantly longer OS in patients with bronchial NET, GEP-NET and midgut NET than in a nonrandomized control group. The total incidence of acute myeloid leukaemia (AML) and myelodysplastic syndrome (MDS) was 2.2%. No PRRT-related grade III/IV nephrotoxicity was observed. CONCLUSION: A cumulative dose of up to 60.5 GBq salvage PRRT with [177Lu-DOTA,Tyr3]octreotate is safe and effective in patients with progressive disease (relapse-PD) following I-PRRT with [177Lu-DOTA,Tyr3]octreotate. Safety appears similar to that of I-PRRT as no higher incidence of AML or MDS was observed. No grade III/IV renal toxicity occurred after retreatment.

Expression of p27Kip1 and p18Ink4c in human multiple endocrine neoplasia type 1-related pancreatic neuroendocrine tumors.

PURPOSE: Pancreatic neuroendocrine tumors are a major manifestation of multiple endocrine neoplasia type 1 (MEN1). This tumor syndrome is caused by germline mutations in MEN1, encoding menin. Insight into pathogenesis of these tumors might lead to new biomarkers and therapeutic targets for these patients. Several lines of evidence point towards a role for p27Kip1 and p18Ink4c in MEN1-related tumor development in animal models for MEN1, but their contribution to human MEN1-related pancreatic neuroendocrine tumor development is not known. METHODS: In this study, we characterized protein expression of p27Kip1 and p18Ink4c in human MEN1-related PanNETs by immunohistochemistry. From the nationwide DutchMEN1 Study Group database including > 90% of the Dutch MEN1 population, MEN1-patients, who underwent pancreatic surgery, were selected. A tissue micro-array was constructed with available paraffin tissue blocks, and PanNETs from 61 MEN1 patients were eligible for analysis. RESULTS: Expression of p27Kip1 was high in 57 (93%) PanNETs and 67% of the tumors showed low expression of p18Ink4c (67.3%). No association was found between expression of either p27Kip1 or p18Ink4c and clinic-pathological characteristics. CONCLUSIONS: These findings indicate that loss of p18Ink4c, but not p27Kip1, is a common event in the development of MEN1-related PanNETs. Restoration of p18Ink4c function through CDK4/6 inhibitors could be a therapeutic option for MEN1-related PanNETs.

Clinical benefit of systemic treatment in patients with advanced pancreatic and gastrointestinal neuroendocrine tumours according to ESMO-MCBS and ASCO framework.

Background: Assessment of clinical benefit of systemic treatments of rare diseases including gastroenteropancreatic neuroendocrine tumours (GEP-NET) is challenging. Recently several tools have been developed to grade the clinical benefit of cancer drugs. The European Society for Medical Oncology (ESMO) has developed the ESMO Magnitude of Clinical Benefit Scale (ESMO-MCBS). The American Society of Clinical Oncology (ASCO) has developed and revised the ASCO framework consisting of the Net Health Benefit (NHB) score juxtaposed against the costs of the treatment. In this review, we graded systemic treatments for GEP-NET patients with both frameworks. Methods: The electronic databases (PubMed and EMBASE) were searched for papers reporting comparative trials, conducted in adult GEP-NET patients in the English language. Papers were assessed according to the ESMO-MCBS and the NHB part of the ASCO revised Framework (NHB-ASCO-F) by four independent assessors, and discrepancies were discussed. Results: The search yielded 32 trials of which 6 were eligible for grading with the ESMO-MCBS resulting in scores of 2 or 3. Eight trials were eligible for grading with the NHB-ASCO-F, resulting in scores between 37.6 and 57.4. Trials that were not primary assessable by the tools were analysed separately. Consensus between assessors was reached in 68% of trials with the ESMO-MCBS and in 23% of trials with the NHB-ASCO-F. Conclusion: The currently used systemic treatments for GEP-NET patients had low scores according to the NHB-ASCO-F and none could be graded as meaningful clinical beneficial according to the ESMO-MCBS. Despite the low incidence, the heterogeneous patient population and relatively long natural course of NET, future studies on new treatment modalities should aim for high clinical benefit outcomes.

A randomized, open-label, phase 2 study of everolimus in combination with pasireotide LAR or everolimus alone in advanced, well-differentiated, progressive pancreatic neuroendocrine tumors: COOPERATE-2 trial.

Background: Several studies have demonstrated the antitumor activity of first-generation somatostatin analogs (SSAs), primarily targeting somatostatin receptor (sstr) subtypes 2 and 5, in neuroendocrine tumors (NET). Pasireotide, a second-generation SSA, targets multiple sstr subtypes. We compared the efficacy and safety of pasireotide plus everolimus to everolimus alone in patients with advanced, well-differentiated, progressive pancreatic NET. Patients and methods: Patients were randomized 1 : 1 to receive a combination of everolimus (10 mg/day, orally) and pasireotide long-acting release (60 mg/28 days, intramuscularly) or everolimus alone (10 mg/day, orally); stratified by prior SSA use, and baseline serum chromogranin A and neuron-specific enolase. The primary end point was progression-free survival (PFS). Secondary end points included overall survival, objective response rate, disease control rate, and safety. Biomarker response was evaluated in an exploratory analysis. Results: Of 160 patients enrolled, 79 were randomized to the combination arm and 81 to the everolimus arm. Baseline demographics and disease characteristics were similar between the treatment arms. No significant difference was observed in PFS: 16.8 months in combination arm versus 16.6 months in everolimus arm (hazard ratio, 0.99; 95% confidence interval, 0.64-1.54). Partial responses were observed in 20.3% versus 6.2% of patients in combination arm versus everolimus arm; however, overall disease control rate was similar (77.2% versus 82.7%, respectively). No significant improvement was observed in median overall survival. Adverse events were consistent with the known safety profile of both the drugs; grade 3 or 4 fasting hyperglycemia was seen in 37% versus 11% of patients, respectively. Conclusions: The addition of pasireotide to everolimus was not associated with the improvement in PFS compared with everolimus alone in this study. Further studies to delineate mechanisms by which SSAs slow tumor growth in NET are warranted.

Midgut neuroendocrine tumor patients have a depleted gut microbiome with a discriminative signature.

RATIONALE: When compared to other types of cancer, the prevalence of midgut neuroendocrine tumors (NET) has disproportionally increased over the past decades. To date, there has been very little progress in discovering (epi)genetic drivers and treatment options for these tumors. Recent microbiome research has revealed that enteroendocrine cells communicate with the intestinal microbiome and has provided novel treatment targets for various other cancer types. Hence, our aim was to analyze the role of the gut microbiome in midgut NET patients. METHODS: Fecal samples, prospectively collected from patients and control subjects, were analyzed with next generation 16S sequencing. Patients with neuroendocrine carcinomas and recent antibiotics use were excluded. Relevant variables were extracted from questionnaires and electronic health records. Microbial composition was compared between patients and controls as well as between groups within the patient cohort. RESULTS: 87 midgut NET patients and 95 controls were included. Midgut NET patients had a less rich and diverse gut microbiome than controls (p < 0.001). Moreover, we identified 31 differentially abundant species and a gut microbial signature consisting of 17 species that was predictive of midgut NET presence with an area under the receiver operating characteristic curve of 0.863. Gut microbial composition was not directly associated with the presence of the carcinoid syndrome, tumor grade or multifocality. Nonetheless, we did observe a potential link between microbial diversity and the presence of carcinoid syndrome symptoms within the subset of patients with elevated 5-hydroxyindolacetic acid levels. CONCLUSION: Midgut NET patients have an altered gut microbiome which suggests a role in NET development and could provide novel targets for microbiome-based diagnostics and therapeutics.

The peripheral blood compartment in patients with Graves' disease: activated T lymphocytes and increased transitional and pre-naive mature B lymphocytes.

Graves' disease (GD) is an autoimmune disease that involves aberrant B and T lymphocyte responses. Detailed knowledge about lymphocyte subpopulation composition will therefore enhance our understanding of the pathogenesis of GD and might support the development of new immunomodulatory treatment approaches. The aim of this study was to gain detailed insight into the composition of the peripheral blood lymphocyte compartment in GD before and during anti-thyroid drug therapy. Major B and T lymphocyte subpopulations were investigated by flow cytometry in peripheral blood from newly diagnosed GD patients (n = 5), GD patients treated with anti-thyroid drugs (n = 4), patients with recurrent GD (n = 7) and healthy controls (HC; n = 10). In GD patients, numbers of activated T lymphocytes [human leucocyte antigen D-related (HLA-DR)⁺ and CD25⁺] were increased. The B lymphocyte compartment in GD was characterized by significantly higher numbers of transitional (CD38(high) CD27⁻, P < 0.03) and pre-naive mature (CD38(low) CD27⁻ IgD⁺ CD5⁺, P < 0.04) B lymphocytes, while memory populations were slightly decreased. The increased numbers of CD5⁺, transitional and pre-naive mature B lymphocytes correlated positively with fT4 plasma levels. GD is associated with increased numbers of activated T lymphocytes and transitional and pre-naive mature CD5⁺ B lymphocytes within the peripheral blood. The increase in CD5⁺ B lymphocytes was due mainly to an increase in transitional and pre-naive mature B lymphocytes. Increased fT4 plasma levels might be associated with this increase in transitional and pre-naive mature CD5⁺ B lymphocytes.

Hypercoagulability in Cushing's syndrome: prevalence, pathogenesis and treatment.

Cushing's syndrome is not only accompanied by an increased prevalence of cardiovascular disease but also by a hypercoagulable state that is reflected by an increased incidence of venous thromboembolism. Overall, patients with CS have been reported to have a more than 10-fold increased risk of developing venous thromboembolism. Moreover, the incidence of postoperative thrombosis has been shown to be comparable to the risk after major orthopaedic surgery. Hypercoagulability in CS is due to both increased production of procoagulant factors with activation of the coagulation cascade and an impaired fibrinolytic capacity, resulting in a shortened activated partial thromboplastin time and an increased clot lysis time respectively. Although these abnormalities seem to improve 1 year following successful surgery, they do not yet normalize. Therefore, sustained biochemical remission might be required to fully resolve the hypercoagulable state in CS. Considering the risk of venous thromboembolism in uncontrolled CS there may be a rationale to give patients with active CS thromboprophylaxis. So far this seems warranted following surgical interventions. However, further studies are needed to determine the optimal dosage and duration of thromboprophylaxis.

Cortisol diurnal rhythm and quality of life after successful medical treatment of Cushing's disease.

Cushing's disease (CD) is associated with severely impaired quality of life (QoL). Moreover, the physiological cortisol diurnal rhythm (CDR) is disturbed in CD. QoL can improve after successful surgery, the primary treatment for CD. We evaluated the effects of medical treatment on QoL and CDR. In 17 patients, stepwise medical treatment was applied with the somatostatin analog pasireotide, the dopamine agonist cabergoline and the adrenal-blocking agent ketoconazole. After 80 days, 15/17 (88%) patients had reached normal urinary free cortisol excretion (UFC). Subsequently, patients continued medical therapy or underwent surgery. UFC, plasma and salivary CDR and QoL-related parameters (assessed using 5 questionnaires: Nottingham Health Profile, Hospital Anxiety and Depression Scale, Multidimensional Fatigue Index-20, RAND-36, CushingQoL) were measured. At baseline, 5/17 patients had preserved CDR. In 6/12 patients with disturbed baseline CDR, recovery was observed, but without any correlation with QoL. QoL was significantly impaired according to 18/20 subscales in CD patients compared to literature-derived controls. According to the RAND-36 questionnaire, patients reported more pain at day 80 (p < 0.05), which might reflect steroid-withdrawal. Generally, QoL did not improve or deteriorate after 80 days. CushingQoL scores seemed to improve after 1 year of remission in three patients that continued medical therapy (p = 0.11). CDR can recover during successful pituitary- and adrenal-targeted medical therapy. Patients with CD have impaired QoL compared to controls. Despite the occurrence of side-effects, QoL does not deteriorate after short-term biochemical remission induced by medical therapy, but might improve after sustained control of hypercortisolism.

Unfavorable biological behavior and treatment response of neuroendocrine ovarian metastases of midgut neuroendocrine tumors.

Neuroendocrine ovarian metastases (NOM) predominantly derive from midgut neuroendocrine tumors (NETs) and develop in about 25% of women with advanced stage of this malignancy. Little is known of the growth rate and treatment response of NOM. We therefore evaluated the efficacy of different management options for patients with NOM, including peptide receptor radionuclide therapy (PRRT), somatostatin analogues (SSAs) and oophorectomy. Records were screened for patients with well-differentiated NOM of midgut origin that presented in our NET referral center between 1991 and 2022. Progression-free survival (PFS) and tumor growth rate (TGR) of ovarian and extra-ovarian metastases were determined using RECIST (response evaluation criteria in solid tumors) 1.1. In 12 available patients undergoing PRRT, NOM were associated with a shorter PFS than extra-ovarian metastases (P = 0.003). While PRRT induced a similar decrease in TGR for ovarian and extra-ovarian lesions in nine patients with available data (-2.3 vs -1.4, P > 0.05), only the TGR of NOM remained positive after PRRT. In 16 patients treated with SSAs, the TGR of NOM was almost three times that of extra-ovarian lesions during treatment (2.2 vs 0.8, P = 0.011). Oophorectomy was performed in 46 of the 61 included patients and was significantly associated with a prolonged OS (115 vs 38 months, P < 0.001). This association persisted after propensity score matching and correction for tumor grade and simultaneous tumor debulking. In conclusion, NOM have a higher TGR compared to extra-ovarian metastases, resulting in a shorter PFS after PRRT. Bilateral salpingo-oophorectomy should be considered for postmenopausal women with NOM undergoing surgery for metastatic midgut NETs.

Lutetium-labelled peptides for therapy of neuroendocrine tumours.

Treatment with radiolabelled somatostatin analogues is a promising new tool in the management of patients with inoperable or metastasized neuroendocrine tumours. Symptomatic improvement may occur with (177)Lu-labelled somatostatin analogues that have been used for peptide receptor radionuclide therapy (PRRT). The results obtained with (177)Lu-[DOTA(0),Tyr(3)]octreotate (DOTATATE) are very encouraging in terms of tumour regression. Dosimetry studies with (177)Lu-DOTATATE as well as the limited side effects with additional cycles of (177)Lu-DOTATATE suggest that more cycles of (177)Lu-DOTATATE can be safely given. Also, if kidney-protective agents are used, the side effects of this therapy are few and mild and less than those from the use of (90)Y-[DOTA(0),Tyr(3)]octreotide (DOTATOC). Besides objective tumour responses, the median progression-free survival is more than 40 months. The patients' self-assessed quality of life increases significantly after treatment with (177)Lu-DOTATATE. Lastly, compared to historical controls, there is a benefit in overall survival of several years from the time of diagnosis in patients treated with (177)Lu-DOTATATE. These findings compare favourably with the limited number of alternative therapeutic approaches. If more widespread use of PRRT can be guaranteed, such therapy may well become the therapy of first choice in patients with metastasized or inoperable neuroendocrine tumours.

Rapid decrease in adrenal responsiveness to ACTH stimulation after successful pituitary surgery in patients with Cushing's disease.

OBJECTIVE: The aim of this study was to investigate the effects of transsphenoidal surgery (TS) on the adrenal sensitivity to ACTH (adrenocorticotropin) stimulation in patients with Cushing's disease (CD). METHODS: We measured the cortisol response to 1 µg synthetic ACTH (1-24) 6 days after pituitary surgery in 45 patients with CD. Mean follow-up period was 56·5 months (SE 4·7). RESULTS: In 24 of 28 patients in sustained remission after pituitary surgery, peak cortisol concentrations below 774 nm (28·0 µg/dl) were recorded after stimulation with 1 µg synthetic ACTH (86%). Two patients with recurrent disease after initial remission (late relapse) also showed ACTH-stimulated peak cortisol levels below 774 nM. Fourteen of 15 patients with persistent CD after surgery (early failure) showed absolute peak cortisol levels >774 nm in response to ACTH stimulation. CONCLUSION: Patients in remission after pituitary surgery for CD showed a rapid decrease of adrenal responsiveness to exogenous ACTH stimulation. This phenomenon may be explained by ACTH-receptor down-regulation in the adrenal cortex after complete removal of the pituitary corticotroph adenoma. In our study, the postoperative low-dose ACTH stimulation test had a sensitivity of 93% and a specificity of 87% in predicting immediate remission of CD after pituitary surgery.