[18F]FET PET/MRI: An Accurate Technique for Detection of Small Functional Pituitary Tumors.

Small functional pituitary tumors can cause severely disabling symptoms and early death. The gold standard diagnostic approach includes laboratory tests and MRI, with or without inferior petrosal sinus sampling (IPSS). In up to 40% of patients, however, the source of excess hormone production remains unidentified or uncertain. This excludes patients from surgical, Gamma Knife, and CyberKnife therapy and adversely affects overall cure rates. We here assess the diagnostic yield of O-(2-[18F]fluoroethyl)-l-tyrosine ([18F]FET) PET/MRI for detection of small functional pituitary tumors in these patients. Methods: This retrospective analysis included patients with Cushing disease (CD) but prior negative or inconclusive MRI results who underwent [18F]FET PET/MRI between February 1, 2021, and December 1, 2022. PET/MR images and MR images alone were evaluated by experienced nuclear radiologists, neuroradiologists, or radiologists. Postoperative tissue analysis (when performed) was used as a reference standard to assess diagnostic metrics (i.e., sensitivity and positive predictive value). Results were also compared with previously obtained MR images, preceding IPSS, and clinical or biochemical follow-up. Results: Twenty-two patients (68% female; mean age ± SD, 48 ± 15 y; range, 24-68 y) were scanned. All patients showed a clear metabolic focus on [18F]FET PET, whereas reading of the MRI alone yielded a suspected lesion in only 50%. Fifteen patients underwent surgery directed at the [18F]FET-positive focus. Tissue analysis confirmed a pituitary adenoma/pituitary neuroendocrine tumor of the corticotroph cell type (TPIT lineage) in 10 of 15 and a pituicytoma in 1 of 15, rendering a sensitivity of 100% and a positive predictive value of 73%. Lateralization was more accurate with [18F]FET PET/MRI than with IPSS in 33%. Twelve of 16 (75%) patients who received surgical, Gamma Knife, or CyberKnife therapy after [18F]FET PET/MRI reached short-term remission. Conclusion: [18F]FET PET/MRI shows a high diagnostic yield for localizing small functional pituitary tumors. This multimodal imaging technique provides a welcome improvement for diagnosis, planning of surgery, and clinical outcome in patients with Cushing disease, particularly those with repeated negative or inconclusive MRI results with or without IPSS.

Epigenetic Mechanisms Modulated by Glucocorticoids with a Focus on Cushing's Syndrome.

In Cushing's syndrome (CS), prolonged exposure to high cortisol levels results in a wide range of devastating effects causing multisystem morbidity. Despite the efficacy of treatment leading to disease remission and clinical improvement, hypercortisolism-induced complications may persist. Since glucocorticoids use the epigenetic machinery as a mechanism of action to modulate gene expression, the persistence of some comorbidities may be mediated by hypercortisolism-induced long-lasting epigenetic changes. Additionally, glucocorticoids influence microRNA expression which is an important epigenetic regulator as it modulates gene expression without changing the DNA sequence. Evidence suggests that chronically elevated glucocorticoid levels may induce aberrant microRNA expression which may impact several cellular processes resulting in cardio-metabolic disorders. The present article reviews the evidence on epigenetic changes induced by (long-term) glucocorticoid exposure. Key aspects of some glucocorticoid target genes and their implications in the context of Cushing's syndrome are described. Lastly, the effects of epigenetic drugs influencing glucocorticoid effects are discussed for their ability to be potentially used as adjunctive therapy in Cushing's syndrome.

Relacorilant, a Selective Glucocorticoid Receptor Modulator in Development for the Treatment of Patients With Cushing Syndrome, Does Not Cause Prolongation of the Cardiac QT Interval.

OBJECTIVE: To assess the effect of relacorilant, a selective glucocorticoid receptor modulator under investigation for the treatment of patients with endogenous hypercortisolism (Cushing syndrome [CS]), on the heart rate-corrected QT interval (QTc). METHODS: Three clinical studies of relacorilant were included: (1) a first-in-human, randomized, placebo-controlled, ascending-dose (up to 500 mg of relacorilant) study in healthy volunteers; (2) a phase 1 placebo- and positive-controlled thorough QTc (TQT) study of 400 and 800 mg of relacorilant in healthy volunteers; and (3) a phase 2, open-label study of up to 400 mg of relacorilant administered daily for up to 16 weeks in patients with CS. Electrocardiogram recordings were taken, and QTc change from baseline (ΔQTc) was calculated. The association of plasma relacorilant concentration with the effect on QTc in healthy volunteers was assessed using linear mixed-effects modeling. RESULTS: Across all studies, no notable changes in the electrocardiogram parameters were observed. At all time points and with all doses of relacorilant, including supratherapeutic doses, ΔQTc was small, generally negative, and, in the placebo-controlled studies, similar to placebo. In the TQT study, placebo-corrected ΔQTc with relacorilant was small and negative, whereas placebo-corrected ΔQTc with moxifloxacin positive control showed rapid QTc prolongation. These results constituted a negative TQT study. The model-estimated slopes of the concentration-QTc relationship were slightly negative, excluding an association of relacorilant with prolonged QTc. CONCLUSION: At all doses studied, relacorilant consistently demonstrated a lack of QTc prolongation in healthy volunteers and patients with CS, including in the TQT study. Ongoing phase 3 studies will help further establish the overall benefit-risk profile of relacorilant.

Approach to the Patient: Insulinoma.

Insulinomas are hormone-producing pancreatic neuroendocrine neoplasms with an estimated incidence of 1 to 4 cases per million per year. Extrapancreatic insulinomas are extremely rare. Most insulinomas present with the Whipple triad: (1) symptoms, signs, or both consistent with hypoglycemia; (2) a low plasma glucose measured at the time of the symptoms and signs; and (3) relief of symptoms and signs when the glucose is raised to normal. Nonmetastatic insulinomas are nowadays referred to as "indolent" and metastatic insulinomas as "aggressive." The 5-year survival of patients with an indolent insulinoma has been reported to be 94% to 100%; for patients with an aggressive insulinoma, this amounts to 24% to 67%. Five percent to 10% of insulinomas are associated with the multiple endocrine neoplasia type 1 syndrome. Localization of the insulinoma and exclusion or confirmation of metastatic disease by computed tomography is followed by endoscopic ultrasound or magnetic resonance imaging for indolent, localized insulinomas. Glucagon-like peptide 1 receptor positron emission tomography/computed tomography or positron emission tomography/magnetic resonance imaging is a highly sensitive localization technique for seemingly occult, indolent, localized insulinomas. Supportive measures and somatostatin receptor ligands can be used for to control hypoglycemia. For single solitary insulinomas, curative surgical excision remains the treatment of choice. In aggressive malignant cases, debulking procedures, somatostatin receptor ligands, peptide receptor radionuclide therapy, everolimus, sunitinib, and cytotoxic chemotherapy can be valuable options.

Long-term efficacy and safety of subcutaneous pasireotide alone or in combination with cabergoline in Cushing's disease.

Objective: This study evaluated short- and long-term efficacy and safety of the second-generation somatostatin receptor ligand pasireotide alone or in combination with dopamine agonist cabergoline in patients with Cushing's disease (CD). Study design: This is an open-label, multicenter, non-comparative, Phase II study comprising 35-week core phase and an optional extension phase. All patients started with pasireotide, and cabergoline was added if cortisol remained elevated. Eligible patients had active CD, with or without prior surgery, were pasireotide naïve at screening or had discontinued pasireotide for reasons other than safety. Primary endpoint was proportion of patients with a mean urinary free cortisol (mUFC) level not exceeding the upper limit of normal (ULN) at week 35 with missing data imputed using last available post-baseline assessments. Results: Of 68 patients enrolled, 26 (38.2%) received pasireotide monotherapy and 42 (61.8%) received pasireotide plus cabergoline during the core phase. Thirty-four patients (50.0%; 95% CI 37.6-62.4) achieved the primary endpoint, of whom 17 (50.0%) received pasireotide monotherapy and 17 (50.0%) received combination therapy. Proportion of patients with mUFC control remained stable during the extension phase up to week 99. Treatment with either mono or combination therapy provided sustained improvements in clinical symptoms of hypercortisolism up to week 99. Hyperglycemia and nausea (51.5% each), diarrhea (44.1%) and cholelithiasis (33.8%) were the most frequent adverse events. Conclusion: Addition of cabergoline in patients with persistently elevated mUFC on maximum tolerated doses of pasireotide is an effective and well-tolerated long-term strategy for enhancing control of hypercortisolism in some CD patients. Clinical trial registration: https://clinicaltrials.gov/ct2/show/NCT01915303, identifier NCT01915303.

Long-term efficacy and safety of osilodrostat in patients with Cushing's disease: results from the LINC 4 study extension.

Objective: To evaluate the long-term efficacy and safety of osilodrostat in patients with Cushing's disease. Methods: The multicenter, 48-week, Phase III LINC 4 clinical trial had an optional extension period that was initially intended to continue to week 96. Patients could continue in the extension until a managed-access program or alternative treatment became available locally, or until a protocol amendment was approved at their site that specified that patients should come for an end-of-treatment visit within 4 weeks or by week 96, whichever occurred first. Study outcomes assessed in the extension included: mean urinary free cortisol (mUFC) response rates; changes in mUFC, serum cortisol and late-night salivary cortisol (LNSC); changes in cardiovascular and metabolic-related parameters; blood pressure, waist circumference and weight; changes in physical manifestations of Cushing's disease; changes in patient-reported outcomes for health-related quality of life; changes in tumor volume; and adverse events. Results were analyzed descriptively; no formal statistical testing was performed. Results: Of 60 patients who entered, 53 completed the extension, with 29 patients receiving osilodrostat for more than 96 weeks (median osilodrostat duration: 87.1 weeks). The proportion of patients with normalized mUFC observed in the core period was maintained throughout the extension. At their end-of-trial visit, 72.4% of patients had achieved normal mUFC. Substantial reductions in serum cortisol and LNSC were also observed. Improvements in most cardiovascular and metabolic-related parameters, as well as physical manifestations of Cushing's disease, observed in the core period were maintained or continued to improve in the extension. Osilodrostat was generally well tolerated; the safety profile was consistent with previous reports. Conclusion: Osilodrostat provided long-term control of cortisol secretion that was associated with sustained improvements in clinical signs and physical manifestations of hypercortisolism. Osilodrostat is an effective long-term treatment for patients with Cushing's disease. Clinical trial registration: ClinicalTrials.gov, identifier NCT02180217.

Emerging diagnostic methods and imaging modalities in cushing's syndrome.

Endogenous Cushing's syndrome (CS) is a rare disease characterized by prolonged glucocorticoid excess. Timely diagnosis is critical to allow prompt treatment and limit long-term disease morbidity and risk for mortality. Traditional biochemical diagnostic modalities each have limitations and sensitivities and specificities that vary significantly with diagnostic cutoff values. Biochemical evaluation is particularly complex in patients whose hypercortisolemia fluctuates daily, often requiring repetition of tests to confirm or exclude disease, and when delineating CS from physiologic, nonneoplastic states of hypercortisolism. Lastly, traditional pituitary MRI may be negative in up to 60% of patients with adrenocorticotropic hormone (ACTH)-secreting pituitary adenomas (termed "Cushing's disease" [CD]) whereas false positive pituitary MRI findings may exist in patients with ectopic ACTH secretion. Thus, differentiating CD from ectopic ACTH secretion may necessitate dynamic testing or even invasive procedures such as bilateral inferior petrosal sinus sampling. Newer methods may relieve some of the diagnostic uncertainty in CS, providing a more definitive diagnosis prior to subjecting patients to additional imaging or invasive procedures. For example, a novel method of cortisol measurement in patients with CS is scalp hair analysis, a non-invasive method yielding cortisol and cortisone values representing long-term glucocorticoid exposure of the past months. Hair cortisol and cortisone have both shown to differentiate between CS patients and controls with a high sensitivity and specificity. Moreover, advances in imaging techniques may enhance detection of ACTH-secreting pituitary adenomas. While conventional pituitary MRI may fail to identify microadenomas in patients with CD, high-resolution 3T-MRI with 3D-spoiled gradient-echo sequence has thinner sections and superior soft-tissue contrast that can detect adenomas as small as 2 mm. Similarly, functional imaging may improve the identification of ACTH-secreting adenomas noninvasively; Gallium-68-tagged corticotropin-releasing hormone (CRH) combined with PET-CT can be used to detect CRH receptors, which are upregulated on corticotroph adenomas. This technique can delineate functionality of adenomas in patients with CD from patients with ectopic ACTH secretion and false positive pituitary lesions on MRI. Here, we review emerging methods and imaging modalities for the diagnosis of CS, discussing their diagnostic accuracy, strengths and limitations, and applicability to clinical practice.

The Role of the IGF2 Methylation Score in Diagnosing Adrenocortical Tumors with Unclear Malignant Potential-Feasibility of Formalin-Fixed Paraffin-Embedded Tissue.

The differentiation between benign and malignant adrenocortical tumors based on pathological assessment can be difficult. We present a series of 17 patients with unclear malignant tumors, of whom six had recurrent or metastatic disease. The assessment of the methylation pattern of insulin-like growth factor 2 (IGF2) regulatory regions in fresh frozen material has shown to be valuable in determining the malignancy of adrenocortical tumors, although this has not been elaborately tested in unclear malignant tumors. Since fresh frozen tissue was only available in six of the patients, we determined the feasibility of using formalin-fixed paraffin-embedded (FFPE) tissue for this method. We isolated DNA from FFPE tissue and matched the fresh frozen tissue of three patients with adrenocortical carcinoma. Methylation patterns of IGF2 regulatory regions were determined by pyrosequencing using different amounts of bisulfite-converted DNA (5 ng, 20 ng, 40 ng). Compared to fresh frozen tissue, FFPE tissue had a higher failure rate (fresh frozen 0%; FFPE 18.5%) and poor-to-moderate replicability (fresh frozen rho = 0.89-0.99, median variation 1.6%; FFPE rho = -0.09-0.85, median variation 7.7%). There was only a poor-to-moderate correlation between results from fresh frozen and FFPE tissue (rho = -0.28-0.70, median variation 13.2%). In conclusion, FFPE tissue is not suitable for determining the IGF2 methylation score in patients with an unclear malignant adrenocortical tumor using the currently used method. We, therefore, recommend fresh frozen storage of resection material for diagnostic and biobank purposes.

Epigenetic regulation of SST2 expression in small intestinal neuroendocrine tumors.

Background: Somatostatin receptor type 2 (SST2) expression is critical for the diagnosis and treatment of neuroendocrine tumors and is associated with improved patient survival. Recent data suggest that epigenetic changes such as DNA methylation and histone modifications play an important role in regulating SST2 expression and tumorigenesis of NETs. However, there are limited data on the association between epigenetic marks and SST2 expression in small intestinal neuroendocrine tumors (SI-NETs). Methods: Tissue samples from 16 patients diagnosed with SI-NETs and undergoing surgical resection of the primary tumor at Erasmus MC Rotterdam were analysed for SST2 expression levels and epigenetic marks surrounding the SST2 promoter region, i.e. DNA methylation and histone modifications H3K27me3 and H3K9ac. As a control, 13 normal SI-tissue samples were included. Results: The SI-NET samples had high SST2 protein and mRNA expression levels; a median (IQR) of 80% (70-95) SST2-positive cells and 8.2 times elevated SST2 mRNA expression level compared to normal SI-tissue (p=0.0042). In comparison to normal SI-tissue, DNA methylation levels and H3K27me3 levels were significantly lower at five out of the eight targeted CpG positions and at two out of the three examined locations within the SST2 gene promoter region of the SI-NET samples, respectively. No differences in the level of activating histone mark H3K9ac were observed between matched samples. While no correlation was found between histone modification marks and SST2 expression, SST2 mRNA expression levels correlated negatively with DNA methylation within the SST2 promoter region in both normal SI-tissue and SI-NETs (p=0.006 and p=0.04, respectively). Conclusion: SI-NETs have lower SST2 promoter methylation levels and lower H3K27me3 methylation levels compared to normal SI-tissue. Moreover, in contrast to the absence of a correlation with SST2 protein expression levels, significant negative correlations were found between SST2 mRNA expression level and the mean level of DNA methylation within the SST2 promoter region in both normal SI-tissue and SI-NET tissue. These results indicate that DNA methylation might be involved in regulating SST2 expression. However, the role of histone modifications in SI-NETs remains elusive.

Proteomic analysis of small intestinal neuroendocrine tumors and mesenteric fibrosis.

Mesenteric metastases in small intestinal neuroendocrine tumors (SI-NETs) are associated with mesenteric fibrosis (MF) in a proportion of patients. MF can induce severe abdominal complications, and an effective preventive treatment is lacking. To elucidate possible novel therapeutic targets, we performed a proteomics-based analysis of MF. The tumor cell and stromal compartment of primary tumors and paired mesenteric metastases of SI-NET patients with MF (n = 6) and without MF (n = 6) was analyzed by liquid chromatography-mass spectrometry-based proteomics. Analysis of differential protein abundance was performed. Collagen alpha-1(XII) (COL12A1) and complement component C9 (C9) expression was evaluated by immunohistochemistry (IHC) in mesenteric metastases. A total of 2988 proteins were identified. Unsupervised hierarchical clustering showed close clustering of paired primary and mesenteric tumor cell samples. Comparing MF to non-MF samples, we detected differentially protein abundance solely in the mesenteric metastasis stroma group. There was no differential abundance of proteins in tumor cell samples or primary tumor stroma samples. Analysis of the differentially abundant proteins (n = 36) revealed higher abundance in MF samples of C9, various collagens and proteoglycans associated with profibrotic extracellular matrix dysregulation and signaling pathways. Proteins involved in fatty acid oxidation showed a lower abundance. COL12A1 and C9 were confirmed by IHC to have significantly higher expression in MF mesenteric metastases compared to non-MF. In conclusion, proteome profiles of SI-NETs with and without MF differ primarily in the stromal compartment of mesenteric metastases. Analysis of differentially abundant proteins revealed possible new signaling pathways involved in MF development. In conclusion, proteome profiles of SI-NETs with and without MF differ primarily in the stromal compartment of mesenteric metastases. Analysis of differentially abundant proteins revealed possible new signaling pathways involved in MF development.

Cushing's syndrome in the elderly: data from the European Registry on Cushing's syndrome.

OBJECTIVE: To evaluate whether age-related differences exist in clinical characteristics, diagnostic approach, and management strategies in patients with Cushing's syndrome (CS) included in the European Registry on Cushing's Syndrome (ERCUSYN). DESIGN: Cohort study. METHODS: We analyzed 1791 patients with CS, of whom 1234 (69%) had pituitary-dependent CS (PIT-CS), 450 (25%) adrenal-dependent CS (ADR-CS), and 107 (6%) had an ectopic source (ECT-CS). According to the WHO criteria, 1616 patients (90.2%) were classified as younger (<65 years old) and 175 (9.8%) as older (≥65 years old). RESULTS: Older patients were more frequently males and had a lower Body Mass Index (BMI) and waist circumference when compared with the younger. Older patients also had a lower prevalence of skin alterations, depression, hair loss, hirsutism, and reduced libido, but a higher prevalence of muscle weakness, diabetes, hypertension, cardiovascular disease, venous thromboembolism, and bone fractures than younger patients, regardless of sex (P < .01 for all comparisons). Measurement of urinary free cortisol supported the diagnosis of CS less frequently in older patients when compared with the younger (P < .05). An extrasellar macroadenoma (macrocorticotropinoma with extrasellar extension) was more common in older PIT-CS patients than in the younger (P < .01). Older PIT-CS patients more frequently received cortisol-lowering medications and radiotherapy as a first-line treatment, whereas surgery was the preferred approach in the younger (P < .01 for all comparisons). When transsphenoidal surgery was performed, the remission rate was lower in the elderly when compared with their younger counterpart (P < .05). CONCLUSIONS: Older CS patients lack several typical symptoms of hypercortisolism, present with more comorbidities regardless of sex, and are more often conservatively treated.

Dissecting the In Vitro Efficacy of Octreotide and Cabergoline in GH- and GH/PRL-Secreting Pituitary Tumors.

CONTEXT: Cabergoline (CAB) is an off-label medical therapy for acromegaly, overshadowed by first-generation somatostatin receptor ligands, eg, octreotide (OCT). OBJECTIVE: This was a head-to-head comparison between OCT and CAB in inhibiting growth hormone (GH) secretion in primary cultures of GH- and GH/prolactin (PRL)-secreting tumors; we also investigated the role of somatostatin (SST) and dopamine type 2 (D2R) receptor expression. METHODS: We evaluated the antisecretory effect of OCT and CAB, together with receptor mRNA expression, in 23 tumor cultures obtained from acromegaly patients referred to the Erasmus Medical Center (Rotterdam, The Netherlands). GH concentrations in cell culture media were determined after 72-hour OCT and CAB treatment (10 nM). RESULTS: OCT showed a slightly higher efficacy compared with CAB (GH decrease -39.5% vs -32.5%, P = 0.079). The effect of the 2 drugs was superimposable in GH/PRL co-secreting tumors (-42.1% vs -44.8%), where SST1 and D2R had a higher expression compared with the pure GH-secreting tumors (P = 0.020 and P = 0.026). OCT was more effective than CAB in 8/23 cultures, while CAB was more effective than OCT in 3/23 (CAB+ group). In CAB+ tumors, SST1 expression was higher compared with the other groups (P = 0.034). At receiver operating characteristic (ROC) curve analysis, SST1 and D2R discriminated between GH and GH/PRL co-secretion (AUC 0.856, P = 0.013; AUC 0.822, P = 0.024). SST1 was the best predictor of CAB response (≥50% GH reduction, AUC 0.913, P = 0.006; 80% sensitivity, 94% specificity). CONCLUSION: OCT is 5% to 10% more effective than CAB in vitro. SST1 mRNA expression can represent a reliable marker of GH/PRL co-secreting tumors showing a preferential response to CAB treatment.

Peripheral glucocorticoid receptor antagonism by relacorilant with modest HPA axis disinhibition.

Glucocorticoid stress hormones are produced in response to hypothalamic-pituitary-adrenal (HPA) axis activation. Glucocorticoids are essential for physiology and exert numerous actions via binding to the glucocorticoid receptor (GR). Relacorilant is a highly selective GR antagonist currently undergoing a phase 3 clinical evaluation for the treatment of endogenous Cushing's syndrome. It was found that increases in serum adrenocorticotropic hormone (ACTH) and cortisol concentrations after relacorilant treatment were substantially less than the increases typically observed with mifepristone, but it is unclear what underlies these differences. In this study, we set out to further preclinically characterize relacorilant in comparison to the classical but non-selective GR antagonist mifepristone. In human HEK-293 cells, relacorilant potently antagonized dexamethasone- and cortisol-induced GR signaling, and in human peripheral blood mononuclear cells, relacorilant largely prevented the anti-inflammatory effects of dexamethasone. In mice, relacorilant treatment prevented hyperinsulinemia and immunosuppression caused by increased corticosterone exposure. Relacorilant treatment reduced the expression of classical GR target genes in peripheral tissues but not in the brain. In mice, relacorilant induced a modest disinhibition of the HPA axis as compared to mifepristone. In line with this, in mouse pituitary cells, relacorilant was generally less potent than mifepristone in regulating Pomc mRNA and ACTH release. This contrast between relacorilant and mifepristone is possibly due to the distinct transcriptional coregulator recruitment by the GR. In conclusion, relacorilant is thus an efficacious peripheral GR antagonist in mice with only modest disinhibition of the HPA axis, and the distinct properties of relacorilant endorse the potential of selective GR antagonist treatment for endogenous Cushing's syndrome.

Long-Term Outcomes of Submaximal Activities of Peptide Receptor Radionuclide Therapy with 177Lu-DOTATATE in Neuroendocrine Tumor Patients.

In the literature, up to 45% of neuroendocrine tumor (NET) patients who are treated with 177Lu-DOTATATE peptide receptor radionuclide therapy (PRRT) do not receive the intended cumulative activity of 29.6 GBq (800 mCi). The aim of this study was to analyze the efficacy of submaximal activities of PRRT in patients who discontinued treatment for non-disease-related reasons. Methods: We retrospectively included patients with well-differentiated and advanced NETs who underwent PRRT from 2000 until 2019 and did not receive 29.6 GBq of 177Lu-DOTATATE. For comparison, we selected control NET patients who received the intended cumulative activity of 29.6 GBq of 177Lu-DOTATATE between 2000 and 2012. Primary outcomes were progression-free survival (PFS) and tumor response, and the secondary outcome was overall survival (OS). Results: In total, 243 patients received 3.7-27.8 GBq. In 130 patients, the submaximal activity was unrelated to disease (e.g., bone marrow and renal toxicity in 48% and maximal renal absorbed dose in 23%), and they were included. Patients receiving a reduced activity had more bone metastases, a lower body mass index and albumin level, a higher alkaline phosphatase level, and fewer grade 1 tumors than the 350 patients included in the control group. The disease control rate in the reduced-activity group was 85%, compared with 93% for the control group (P = 0.011). The median PFS (95% CI) was 23 mo (range, 21-26 mo) for the reduced-activity group and 31 mo (range, 27-35 mo) for the control group (P = 0.001), and the median OS (95% CI) was 34 mo (range, 28-40 mo) and 60 mo (range, 53-67 mo), respectively (P < 0.0001). With adjustment for relevant confounders in the multivariable Cox regression analyses, cumulative activity was an independent predictor of both PFS and OS. Conclusion: In NET patients treated with a cumulative activity of less than 29.6 GBq of 177Lu-DOTATATE, PRRT was less efficacious in tumor response and survival than in patients who received 29.6 GBq.

The course of C-peptide levels in patients developing diabetes during anti-PD-1 therapy.

INTRODUCTION: Immune checkpoint inhibitor (ICI) associated diabetes is a harmful adverse event (AE) in patients with cancer following anti-programmed (cell) death protein-1 (PD-1) treatment. There are no available biomarkers able to predict this AE. The primary aim of this study was to investigate C-peptide levels as potential predictor for the occurrence of ICI-related diabetes. The secondary aim was to describe the presence of islet autoantibodies and course of pancreatic enzymes in patients with and without ICI-related diabetes. METHODS: From a total of 1318 patients with cancer who started anti-PD-1 treatment 8 cases and 16 controls were studied in this nested case-control study. C-peptide levels, islet autoantibodies, and pancreatic enzymes were measured in prospectively collected blood serum. RESULTS: In cases versus controls, median C-peptide levels were comparable at baseline and before toxicity or at the corresponding time point in controls. No patient had C-peptide levels below reference range before toxicity onset. Two out of eight patients in the ICI-related diabetes group had positive islet autoantibodies, whereas one out of 16 patients in the control group had positive islet autoantibodies. Pancreatic enzymes were elevated before diabetes onset in one patient (13%) and in one control (6%) at the corresponding time point. CONCLUSIONS: In patients developing ICI-related diabetes, changes in C-peptide levels, islet autoantibody positivity, and pancreatic enzymes before ICI-related diabetes onset seem comparable to patients without ICI-related diabetes. (NTR: NL6828).

Corticotroph tumor progression after bilateral adrenalectomy: data from ERCUSYN.

Corticotroph tumor progression after bilateral adrenalectomy/Nelson's syndrome (CTP-BADX/NS) is a severe complication of bilateral adrenalectomy (BADX). The aim of our study was to investigate the prevalence, presentation and outcome of CTP-BADX/NS in patients with Cushing's disease (CD) included in the European Registry on Cushing's Syndrome (ERCUSYN). We examined data on 1045 CD patients and identified 85 (8%) who underwent BADX. Of these, 73 (86%) had follow-up data available. The median duration of follow-up since BADX to the last visit/death was 7 years (IQR 2-9 years). Thirty-three patients (45%) experienced CTP-BADX/NS after 3 years (1.5-6) since BADX. Cumulative progression-free survival was 73% at 3 years, 66% at 5 years and 46% at 10 years. CTP-BADX/NS patients more frequently had a visible tumor at diagnosis of CD than patients without CTP-BADX/NS (P < 0.05). Twenty-seven CTP-BADX/NS patients underwent surgery, 48% radiotherapy and 27% received medical therapy. The median time since diagnosis of CTP-BADX/NS to the last follow-up visit was 2 years (IQR, 1-5). Control of tumor progression was not achieved in 16 of 33 (48%) patients, of whom 8 (50%) died after a mean of 4 years. Maximum adenoma size at diagnosis of CD was associated with further tumor growth in CTP-BADX/NS despite treatment (P = 0.033). Diagnosis of CTP-BADX/NS, older age, greater UFC levels at diagnosis of CD and initial treatment predicted mortality. In conclusion, CTP-BADX/NS was reported in 45% of the ERCUSYN patients who underwent BADX, and control of tumor growth was reached in half of them. Future studies are needed to establish effective strategies for prevention and treatment.

Peptide Receptor Radionuclide Therapy.

The concept of using a targeting molecule labeled with a diagnostic radionuclide for using positron emission tomography or single photon emission computed tomography imaging with the potential to demonstrate that tumoricidal radiation can be delivered to tumoral sites by administration of the same or a similar targeting molecule labeled with a therapeutic radionuclide termed "theranostics." Peptide receptor radionuclide therapy (PRRT) with radiolabeled somatostatin analogs (SSAs) is a well-established second/third-line theranostic treatment for somatostatin receptor-positive well-differentiated (neuro-)endocrine neoplasms (NENs). PRRT with 177Lu-DOTATATE was approved by the regulatory authorities in 2017 and 2018 for selected patients with low-grade well-differentiated gastroenteropancreatic (GEP) NENs. It improves progression-free survival as well as quality of life of GEP NEN patients. Favorable symptomatic and biochemical responses using PRRT with 177Lu-DOTATATE have also been reported in patients with functioning metastatic GEP NENs like metastatic insulinomas, Verner Morrison syndromes (VIPomas), glucagonomas, and gastrinomas and patients with carcinoid syndrome. This therapy might also become a valuable therapeutic option for inoperable low-grade bronchopulmonary NENs, inoperable or progressive pheochromocytomas and paragangliomas, and medullary thyroid carcinomas. First-line PRRT with 177Lu-DOTATATE and combinations of this therapy with cytotoxic drugs are currently under investigation. New radiolabeled somatostatin receptor ligands include SSAs coupled with alpha radiation emitting radionuclides and somatostatin receptor antagonists coupled with radionuclides.

Approach to the Patient: Diagnosis of Cushing Syndrome.

Cushing syndrome results from supraphysiological exposure to glucocorticoids and is associated with significant morbidity and mortality. The pathogenesis includes administration of corticosteroids (exogenous Cushing syndrome) or autonomous cortisol overproduction, whether or not ACTH-dependent (endogenous Cushing syndrome). An early diagnosis of Cushing syndrome is warranted; however, in clinical practice, it is very challenging partly because of resemblance with other common conditions (ie, pseudo-Cushing syndrome). Initial workup should start with excluding local and systemic corticosteroid use. First-line screening tests including the 1-mg dexamethasone suppression test, 24-hour urinary free cortisol excretion, and late-night salivary cortisol measurement should be performed to screen for endogenous Cushing syndrome. Scalp-hair cortisol/cortisone analysis helps in the assessment of long-term glucocorticoid exposure as well as in detection of transient periods of hypercortisolism as observed in cyclical Cushing syndrome. Interpretation of results can be difficult because of individual patient characteristics and hence requires awareness of test limitations. Once endogenous Cushing syndrome is established, measurement of plasma ACTH concentrations differentiates between ACTH-dependent (80%-85%) or ACTH-independent (15%-20%) causes. Further assessment with different imaging modalities and dynamic biochemical testing including bilateral inferior petrosal sinus sampling helps further pinpoint the cause of Cushing's syndrome. In this issue of "Approach to the patient," the diagnostic workup of Cushing syndrome is discussed with answering the questions when to screen, how to screen, and how to differentiate the different causes. In this respect, the latest developments in biochemical and imaging techniques are discussed as well.

Long-term outcomes of osilodrostat in Cushing's disease: LINC 3 study extension.

Objective: To investigate the long-term efficacy and tolerability of osilodrostat, a potent oral 11ß-hydroxylase inhibitor, for treating Cushing's disease (CD). Design/methods: A total of 137 adults with CD and mean 24-h urinary free cortisol (mUFC) > 1.5 × upper limit of normal (ULN) received osilodrostat (starting dose 2 mg bid; maximum 30 mg bid) during the prospective, Phase III, 48-week LINC 3 (NCT02180217) core study. Patients benefiting from osilodrostat at week 48 could enter the optional extension (ending when all patients had received ≥ 72 weeks of treatment or discontinued). Efficacy and safety were assessed for all enrolled patients from the core study baseline. Results: Median osilodrostat exposure from the core study baseline to study end was 130 weeks (range 1-245) and median average dose was 7.4 mg/day (range 0.8-46.6). The reduction in mean mUFC achieved during the core was maintained during the extension and remained ≤ ULN. Of 106 patients, 86 (81%) patients who entered the extension had mUFC ≤ ULN at week 72. Improvements in cardiovascular/metabolic-related parameters, physical manifestations of hypercortisolism (fat pads, central obesity, rubor, striae, and hirsutism in females), and quality of life in the core study were also maintained or improved further during the extension. No new safety signals were reported; 15/137 (10.9%) and 12/106 (11.3%) patients discontinued for adverse events during the core and extension, respectively. Mean testosterone in females decreased towards baseline levels during the extension. Conclusions: Data from this large, multicentre trial show that long-term treatment with osilodrostat sustains cortisol normalisation alongside clinical benefits in most patients with CD and is well tolerated.