Silent Corticotroph Adenomas Research Articles

8014 Cushing’s Syndrome: Two Sides of The Spectrum

Abstract Disclosure: M. Aguilera: None. A. Vu: None. J. Shakil: None. R. Al-Ward: None. Introduction: Cushing’s syndrome (CS) is a rare condition with an annual incidence of 2-8 per million. Endogenous CS is mainly due to corticotroph adenoma of the pituitary followed by excessive glucocorticoid production from adrenal and ectopic sources. CS has significant morbidity and mortality hence the need for timely diagnosis. The varied presentations often pose great challenges in identifying the source of hypercortisolism. We present two unusual cases of CS with distinct clinical presentations and atypical laboratory profiles. Case 1: 25-year-old male with no medical history presented with 9 months of facial puffiness, weight gain, fluid retention, hypertension and blurred vision. Physical examination revealed round facies, bilateral supraclavicular fat pads and wide abdominal striae. Laboratory workup showed markedly elevated ACTH 537 pg/mL [7.2-63 pg/mL], serum cortisol 8.5 ug/dL [6.2-19.4 ug/dl], 24-hour urine free cortisol (UFC) 30 [5-62 ug/24H] and normal late-night salivary cortisol (LNSC). Repeat workup a month later showed serum cortisol of 56ug/dL, ACTH 874 pg/dL, 24-hour UFC of 11880ug/24H and elevated LNSC. Pituitary MRI showed a large heterogenous 3.1 cm partially cystic sellar mass with suprasellar extension. Due to significantly elevated ACTH and short duration of symptoms, we suspected an ectopic source. Due to initial negative testing, except for high ACTH level, a silent corticotroph adenoma was also considered. The patient underwent transsphenoidal resection resulting in significant decrease of cortisol and ACTH postoperatively. Pathology showed a corticotroph adenoma with Ki-67 index of <1%. Case 2: 47-year-old woman with medical history of obesity, polycystic ovary syndrome and a stable 1 cm lung nodule since 2020, presented with fluid retention, worsening acne and resistant hypertension over a 1-year period. She required hospitalization for hypertensive emergency and hypokalemia. Laboratory data showed morning serum cortisol 28 ug/dL, ACTH of 90.1 pg/mL, 24-hour UFC 346 ug/24H, elevated LNSC on two occasions and cortisol 24.3 ug/dl after a 1mg dexamethasone suppression. MRI did not show a pituitary mass. PET dotatate scan revealed a tracer avid 1 cm right upper lobe pulmonary nodule. She underwent a right upper lobe lobectomy, resulting in a significant decrease in cortisol and ACTH levels on postoperative day 1. Pathology confirmed a typical carcinoid tumor. Discussion: High ACTH levels and a short symptom duration often point to ectopic production, paraneoplastic syndromes or corticotroph carcinomas. Cushing's disease typically exhibits mildly elevated ACTH levels, but our cases deviate from this norm, complicating source identification. This atypical presentation highlights the complexity of Cushing's syndrome, challenging conventional diagnostic paradigms. Presentation: 6/1/2024

8594 Pasireotide and Pasireotide Combined Treatment in Aggressive, Giant Pituitary Neuroendocrine Tumours

Abstract Disclosure: K. Ciszek: None. A. Bogusławska: None. M. Komisarz-Calik: None. J. Kunicki: None. A. Hubalewska-Dydejczyk: None. A. Gilis-Januszewska: None. Pasireotide is a second-generation somatostatin analogue that gained recognition as a treatment option for acromegaly and Cushing disease. Recently, there are single reports of pasireotide treatment in other subtype of pituitary neuroendocrine tumours (PitNETs).We present a case series of aggressive, giant PitNETs which were treated with pasireotide alone or as combined multimodal treatment. Case 1: A 59-year-old male presented in our Unit due to severe headaches and visual field deficits. The patient underwent transsphenoidal surgery (TSS) ten years ago. Histopathology results showed partially acidophilic adenoma (FSH- LH- GH- ACTH- PRL-). Control MRI showed tumour regrowth - 56x56x89mm and invasion of local structures. The patient was qualified for radiotherapy, to which he did not consent. Due to the progression of symptoms, temozolomide and pasireotide were introduced. After 5 months, significant improvement in headaches and vision was observed. In MRI stable pituitary mass was noted. Case 2: A 17-year-old male presented in our clinic due to daily severe headaches and peripheral vision loss who underwent two non-radical surgeries for dopamine-resistant giant prolactinoma. In control MRIs progressing mass 38x34x33mm invading local structures was observed. Due to resistance to dopamine agonists and worsening of the symptoms, pasireotide was introduced resulting in a decrease of headaches and improvement in vision. The tumour size remained stationary. Case 3: A 59-year-old male presented with severe headaches and life threatening tumour mass effect.In MRI a 48x48x33mm mass was observed. The patient underwent two non-radical TSS, 4 cycles of pasireotide, and cyberknife treatment. Histopathology showed gonadotroph PitNET. MRI showed tumour shrinkage to 45x46x29mm, with persistent severe headaches. The patient was re-qualified for pasireotide treatment. Case 4: A 33-year-old male reported to the Clinic due to severe headaches and vomiting. In MRI pituitary mass 33x39x55mm and a cerebral oedema were revealed. TSS with external ventricular drainage was performed -histopathology results showed densely granulated silent corticotroph adenoma subtype 1, Ki67<1%. After 3 months, MRI showed tumour progression to 39x40x30mm. Two emergency TSS followed by stereotactic radiotherapy were performed. Combined therapy with pasireotide, cabergoline and temozolomide was introduced. After 18 months, stabilization of the disease was observed with the complete disappearance of headaches. Conclusions: Our study demonstrates the clinical potential of pasireotide treatment in aggressive, giant PitNETs. The therapy alone, or in combination has a potential role in reducing the tumour size, and allows the stabilization of the disease. The analgesic and anti-inflammatory effect of pasireotide could potentially alleviate headaches in this subset of patients. Presentation: 6/2/2024

PCSK1N as a tumor size marker and an ER stress response protein in corticotroph pituitary adenomas.

Silent corticotroph adenoma (SCA) exhibits more tumor aggressiveness features than functioning adenomas (FCA). We aimed to investigate PCSK1N expression in CA and examine if ER stress-induced responses affect cell survival in a corticotroph tumor cell model. Clinical and imaging characteristics were recorded in 33 patients with FCA (20 women, 11 macroadenomas) and 18 SCA (8 women, all macroadenomas). Gene expression of proopiomelanocortin (POMC), T-box transcription factor 19(TBX19)/TPIT, proprotein convertase subtilisin/kexin type 1(PCSK1)/PC1/3, and its inhibitor PCSK1N, was measured by RT-qPCR in adenoma tissue.Mouse pituitary corticotroph tumor (AtT-20) cells were treated with tanespimycin (17-AAG), a HSP90 chaperone inhibitor, to induce ER stress, followed by gene and protein analyses. POMC, TPIT, and PCSK1 expression were higher, whereas PCSK1N was lower in FCA compared to SCA. PCSK1N correlated with POMC (rs= -0.514, p <0.001), TPIT (rs= -0.386, p = 0.005), PCSK1 (rs= -0.3691, p = 0.008), and tumor largest diameter (rs= 0.645, p <0.001), in all CA. Induction of ER stress by 17-AAG in AtT-20 cells led to a decrease of POMC and an increase of PCSK1N gene expression at 24h. Moreover, a downregulation of cell cycle, apoptosis, and senescence pathways, and alterations in cell adhesion and cytoskeleton were observed at the protein level. PCSK1N is higher in SCA compared with FCA, and associated with corticotroph cell markers and tumor size. PCSK1N is likely to be part of the adaptive response to ER stress, potentially conferring a survival advantage to the corticotroph tumor cell in conjunction with other proteins.

Treatment Strategies and Long-Term Outcomes in Silent Corticotroph Adenomas: A Single-Center Retrospective Study of 367 Cases.

Silent corticotroph adenoma (SCA) is a high-risk pituitary neuroendocrine tumor (PitNET) which exhibits more aggressive behavior than other nonfunctioning PitNETs. Some SCAs are observed to recur after total resection (TR). We aim to discuss the long-term outcomes after endoscopic endonasal surgery for SCAs and explore optimal treatment after operation. Clinical data and intraoperative videos from 367 SCAs who underwent endoscopic endonasal surgery were retrospectively collected. Patients were categorized into TR and subtotal resection (STR) groups according to 3-month postoperative MRIs. Based on close-up intraoperative observation of the relationship between tumor and pituitary gland, diaphragm, and medial wall cavernous sinus, patients in the TR group were further subdivided into gross total resection (GTR) and near total resection (NTR) groups. Patients in the STR group were subdivided as STR followed by observation (STR + ob) and STR followed by adjuvant stereotactic radiosurgery (SRS) (STR + SRS). Kaplan-Meier analysis was used to compare the event-free survival among these subgroups. Headache (27.5%) and vision loss (55.3%) were the most common presenting symptoms. Cavernous sinus (CS) invasion was confirmed intraoperatively in 167 (45.5%) patients. After operation, 175 (47.7%), 83 (22.6%), 32 (8.7%), and 77 (21%) patients were divided into GTR, NTR, STR + ob, and STR + SRS groups, respectively. The mean follow-up time was 40.9 ± 25.8 months. There were 0, 17 (20.5%), 9 (28.1%), and 4 (5.2%) patients noted to have PitNET recurrence or progression in GTR, NTR, STR + ob, and STR + SRS groups, respectively. Event-free survival distribution in the NTR group was similar to that in the STR + ob group (P = .696), which was significantly lower than that in the STR + SRS group (P = .008). Adrenocorticotropic hormone (ACTH)-negative SCAs have lower preoperative ACTH levels and were more likely to invade CS than ACTH-positive SCAs. CS invasion was commonly seen in SCAs, often precluding GTR. Radical surgery and close follow-up were proposed. Early postoperative adjuvant SRS for remnant tumor should be considered.

Silent Corticotroph Adenomas Demonstrate Predilection for Sphenoid Sinus, Cavernous Sinus, and Clival Invasion Compared with Other Subtypes

Nonfunctional pituitary neuroendocrine tumors (PitNETs) exhibit wide variability in growth pattern based on subtype. Silent corticotroph adenomas (SCAs) demonstrate aggressive growth compared with other nonfunctional pituitary adenomas (NFPAs), especially into the cavernous sinus. In this study, we sought to characterize other growth patterns of SCAs compared with NFPAs. We performed a retrospective analysis of all patients with nonfunctional PitNETs treated with surgical resection via endoscopic endonasal approach at a single institution from August 1, 2018, to May 11, 2024. Preoperative computed tomography and magnetic resonance imaging were reviewed to determine extension into the suprasellar space, sphenoid sinus, cavernous sinus, and clivus. The study comprised 91 patients, including 20 SCAs and 71 NFPAs. SCAs demonstrated significantly greater rates of growth into the sphenoid sinus (55.0% vs. 23.94%, P= 0.013), clivus (65.0% vs. 16.9%, P < 0.0001), and cavernous sinus (defined as Knosp grade 3 or 4; 55.0% vs. 23.35%, P= 0.016). Other NFPAs were more likely to grow into the suprasellar space (92.96% vs. 75.0%, P= 0.038). Tumor volume was similar between groups (11.93 cm3 vs. 9.06 cm3, P= 0.2). Silent corticotroph PitNETs demonstrate predilection for invasion of bony structures, with higher rates of growing through the sellar floor into the sphenoid sinus, growing posteroinferiorly into the clivus and laterally into the cavernous sinuses. Other nonfunctional PitNETs tended to follow the path of least resistance, growing superiorly into the suprasellar space. These differences in growth patterns may account for some of the clinical challenges of treating silent corticotroph PitNETs.

Challenges in diagnosis and management of silent corticotroph adenomas: insights from three case studies and literature review

Challenges in diagnosis and management of silent corticotroph adenomas: insights from three case studies and literature review

Effects of the Cortisol Milieu on Tumor-Infiltrating Immune Cells in Corticotroph Tumors.

Corticotrophs are susceptible to lymphocyte cytotoxicity, as seen in hypophysitis, suggesting that an immunological approach may be a potential strategy for corticotroph-derived tumors. We aimed to clarify whether corticotroph tumors that induce hypercortisolemia (ACTHomas) could be targets for immunotherapy. Tumor-infiltrating immune cells were immunohistochemically analyzed. ACTHomas were compared with other pituitary tumors, and further divided into 3 different cortisol-exposed milieus: Naïve (ACTHomas without preoperative treatment), Met (ACTHomas with preoperative metyrapone), and SCA (silent corticotroph adenomas). A 3-dimensional cell culture of resected tumors was used to analyze the effects of immune checkpoint inhibitors. The number of tumor-infiltrating lymphocytes (TILs) was low in ACTHomas. Among these, the number of CD8+ cells was lower in ACTHomas than in both somatotroph and gonadotroph tumors (both P < .01). Then we compared the differences in TILs among Naïve, Met, and SCA. The number of CD4+ cells, but not CD8+ cells, was higher in both Met and SCA than in Naïve. Next, we investigated tumor-associated macrophages, which could negatively affect T cell infiltration. The numbers of CD163+ and CD204+ cells were positively associated with cortisol levels. Moreover, tumor size was positively correlated with the number of CD204+ cells. We found the possibility that ACTHomas were immunologically cold in a cortisol-independent manner. In contrast, the tumor infiltration of CD4+ cells and M2-macrophages were associated with the cortisol milieu. Future studies are needed to validate these results and develop effective immunotherapy while considering the cortisol milieu.

Delineating the Spectrum of Pituitary Adenoma Based on the WHO 2017 Classification.

The WHO 2017 classification of endocrine tumors incorporates lineage-specific transcription factors (TF) and hormone expression for the classification of pituitary adenoma (PA). There is paucity of reports describing the spectrum of PA based on this classification. The aim of this study was to delineate the spectrum of PA based on WHO 2017 classification of endocrine tumors. PA diagnosed in the year 2018 were studied. H and E and hormonal immunohistochemistry (IHC) for GH, PRL, ACTH, TSH, FSH, LH, CK, T-Pit and MIB-1 were performed and the results were analyzed. The cohort included 88 cases. M: F ratio was 2:1. Clinically, 22 (25%) were functional and 66 (75%) were non-functional adenomas. Amongst the clinically functional adenomas, GH secreting adenomas were the commonest (68%). Majority (83%) of non-functional adenomas were hormone positive with gonadotroph adenomas being the commonest (72.7%). Eleven (12.5%) PA were clinically and hormonally silent. Three of these showed intense nuclear T-Pit positivity, classifying them under silent corticotroph adenoma. Lineage of the remaining eight adenomas remained undetermined, since, IHC for Pit-1 and SF-1 was not performed. The aggressive adenomas identified by IHC included sparsely granulated somatotroph adenoma, Crooke cell adenoma, silent corticotroph adenoma, densely granulated lactotroph adenoma in men and constituted 17% of the PA. Four (4/88) cases were clinically invasive. A large majority of PA including aggressive adenomas can be identified by IHC. Addition of T-Pit helped to identify silent corticotroph adenoma. Pit -1 and SF-1 TF would help identify plurihormonal Pit-1 PA and null cell adenomas.

SAT618 Uncovering The Role Of O-glcnacylation In Pituitary Adenoma Pathogenesis: Insights From Corticotroph Tumors

Abstract Disclosure: L.J. Massman: None. R. Gonzalez: None. B. Laing: None. D. Coss: None. A.G. Ioachimescu: None. N. Zwagerman: None. S. Olivier-Van Stichelen: None. Functioning corticotroph pituitary adenomas are associated with high mortality, morbidity, and a high propensity of biochemical recurrence postoperatively. Silent corticotroph adenomas cause mass-effect manifestations and have an increased risk for tumor regrowth. The pathogenetic mechanisms responsible for the clinical course of corticotroph PA are poorly understood. In this study, we investigated the role of the O-GlcNAc posttranslational modification in their pathophysiology. O-GlcNAcylation is involved in protein signaling pathways and deregulated in cancers and diabetes. First, we performed RNA-sequencing in functioning and silent corticotroph and gonadotroph adenomas (n=25). We discovered that O-GlcNAc enzymes were upregulated in ACTH-secreting corticotroph tumors and correlated with larger, more invasive tumors. Also, an in vitro mechanistic analysis of corticotroph tumor cells (ATt-20) demonstrated that O-GlcNAcylation was essential for their proliferation and secretory ability. Specifically, O-GlcNAcylation affected Proopiomelanocortin mRNA splicing and stability, suggesting a new mechanism of fast hormonal response in corticotropes. Overall, our study indicates a key role for O-GlcNAcylation in corticotroph adenomas’ cellular proliferation and hypersecretion. Presentation: Saturday, June 17, 2023

A silent corticotroph adenoma: making the case for a pars intermedia origin. Illustrative case.

Silent corticotroph adenomas (SCAs) are the only pituitary adenomas thought to originate from the pars intermedia. This case report presents the rare finding of a multimicrocystic corticotroph macroadenoma displacing the anterior and posterior lobes of the pituitary gland on magnetic resonance imaging (MRI). This finding supports the hypothesis that silent corticotroph adenomas may originate from the pars intermedia and should be considered in the differential for tumors arising from this location. A 55-year-old man presented with an episode of confusion and blurred vision. MRI demonstrated separation of the anterior and posterior glands by a solid-cystic lesion located within the pars intermedia that superiorly displaced the optic chiasm. Endocrinologic evaluation was unremarkable. The differential diagnosis included pituitary adenoma, Rathke cleft cyst, and craniopharyngioma. The tumor was confirmed to be an SCA on pathology and was completely removed through the endoscopic endonasal transsphenoidal approach. The case highlights the importance of preoperative screening for subclinical hypercortisolism for tumors arising from this location. Knowledge of a patient's preoperative functional status is critical and dictates their postoperative biochemical assessment to determine remission. The case also illustrates surgical strategies for resecting pars intermedia lesions without injuring the gland.

A Pituitary Neoplasm with an Aggressive Course: Silent Corticotroph Adenoma

Searchable abstracts of presentations at key conferences in endocrinology ISSN 1470-3947 (print) | ISSN 1479-6848 (online)

Abstract #1406235: Silent Corticotroph Adenomas are More Aggressive than Other Nonfunctional Pituitary Adenomas

Silent corticotroph adenomas (SCAs) are immunopositive for adrenocorticotropic hormone (ACTH) but do not cause Cushing disease. They account for approximately 20% of all corticotroph adenomas and 5% of nonfunctioning pituitary adenomas (NFAs). We present a case of an SCA with extensive invasion outside the sella turcica and causing pathology through mass effect on adjacent structures. A 48-year-old male was found to have a 3.8 cm pituitary mass with invasion of the left cavernous sinus and compression of the optic chiasm during an evaluation of headaches and diplopia. No signs of Cushing syndrome or acromegaly were apparent on examination. Metabolic evaluation was notable for secondary hypothyroidism (TSH 0.7 mIU/L, 0.45-5.33; free T4 0.3 ng/dL, 0.5-1.3) and hypogonadism (LH 2.2 mIU/L, 1.2-8.8; total testosterone 105 ng/dL, 270-1070), though serum prolactin (17.3 ng/mL, 2.6-13.2) and IGF-1 levels (133 ng/mL, 71-224) were unremarkable. ACTH level was increased on multiple measurements (69.9-146.8 μg/dL, 7.2-63.3), but 8 AM cortisol level during an overnight dexamethasone suppression test was only modestly elevated (1.9 μg/dL, expected < 1.8). The patient underwent transsphenoidal surgery (TSS) to remove accessible tumor and relieve symptoms of mass effect. Histopathology was notable for a pituitary adenoma with low Ki-67 proliferation index (< 5%) and 70-80% staining for ACTH. Symptoms recurred approximately 1 y later, and imaging revealed a substantial increase in volume of residual tumor. Unfortunately, the patient died from arterial bleeding during a second attempt at TSS. SCAs are more aggressive than NFAs that fail to stain for an intact pituitary hormone. Patients with SCAs are younger, more likely female, and have a greater likelihood of symptoms at diagnosis than patients with NFAs, though the proportion of SCAs present with extrasellar extension is equivalent to NFAs. SCAs and NFAs progress or recur at the same rate, but time to recurrence for SCAs is more than two-fold faster than for NFAs. Recurrence rate and time to recurrence for SCAs are unaffected by adjuvant radiation. SCAs with extensive staining for ACTH as in this case are more likely to be aggressive than tumors with limited staining for ACTH. Reduced expression of the mismatch repair gene MSH 6/2 may be a driver for the behavior of SCAs. This case illustrates SCAs are a small but challenging subset of NFAs with greater propensity to cause symptoms of mass effect and recur quickly than the typical NFA. Extensive ACTH staining is a poor prognostic sign for tumor recurrence.

Radiomics model and clinical scale for the preoperative diagnosis of silent corticotroph adenomas.

Silent corticotroph adenomas (SCAs) are a subtype of nonfunctioning pituitary adenomas that exhibit more aggressive behavior. However, rapid and accurate preoperative diagnostic methods are currently lacking. The purpose of this study was to examine the differences between SCA and non-SCA features and to establish radiomics models and a clinical scale for rapid and accurate prediction. A total of 260 patients (72 SCAs vs. 188 NSCAs) with nonfunctioning adenomas from Peking Union Medical College Hospital were enrolled in the study as the internal dataset. Thirty-five patients (6 SCAs vs. 29 NSCAs) from Fuzhou General Hospital were enrolled as the external dataset. Radiomics models and an SCA scale to preoperatively diagnose SCAs were established based on MR images and clinical features. There were more female patients (internal dataset: p < 0.001; external dataset: p = 0.028) and more multiple microcystic changes (internal dataset: p < 0.001; external dataset: p = 0.012) in the SCA group. MRI showed more invasiveness (higher Knosp grades, p ≤ 0.001). The radiomics model achieved AUCs of 0.931 and 0.937 in the internal and external datasets, respectively. The clinical scale achieved an AUC of 0.877 and a sensitivity of 0.952 in the internal dataset and an AUC of 0.899 and a sensitivity of 1.0 in the external dataset. Based on clinical information and imaging characteristics, the constructed radiomics model achieved high preoperative diagnostic ability. The SCA scale achieved the purpose of rapidity and practicality while ensuring sensitivity, which is conducive to simplifying clinical work.

Molecular characterization of epithelial-mesenchymal transition and medical treatment related-genes in non-functioning pituitary neuroendocrine tumors.

Different medical therapies have been developed for pituitary adenomas. However, Non-Functioning Pituitary Neuroendocrine Tumors (NF-PitNET) have shown little response to them. Furthermore, epithelial-mesenchymal transition (EMT) has been linked to resistance to medical treatment in a significant number of tumors, including pituitary adenomas. We aimed to evaluate the expression of EMT-related markers in 72 NF-PitNET and 16 non-tumoral pituitaries. To further explore the potential usefulness of medical treatment for NF-PitNET we assessed the expression of somatostatin receptors and dopamine-associated genes. We found that SNAI1, SNAI2, Vimentin, KLK10, PEBP1, Ki-67 and SSTR2 were associated with invasive NF-PitNET. Furthermore, we found that the EMT phenomenon was more common in NF-PitNET than in GH-secreting pituitary tumors. Interestingly, PEBP1 was overexpressed in recurrent NF-PitNET, and could predict growth recurrence with 100% sensitivity but only 43% specificity. In parallel with previously reported studies, SSTR3 is highly expressed in our NF-PitNET cohort. However, SSTR3 expression is highly heterogeneous among the different histological variants of NF-PitNET with very low levels in silent corticotroph adenomas. NF-PitNET showed an enhanced EMT phenomenon. SSTR3 targeting could be a good therapeutic candidate in NF-PitNET except for silent corticotroph adenomas, which express very low levels of this receptor. In addition, PEBP1 could be an informative biomarker of tumor regrowth, useful for predictive medicine in NF-PitNET.

Refractory nonfunctioning pituitary adenomas.

Non-functioning pituitary adenomas (NFPAs) comprise silent tumors of different pituitary lineages that tend to escape early detection and present as invasive macroadenomas with symptoms of mass effect. Incomplete surgical resection is common and may be followed by significant rates of subsequent remnant progression. Pituitary tumors are defined as refractory when resistance to optimal standard therapies including surgery, radiotherapy, and medical treatment is documented. In the absence of approved medications for the treatment of NFPAs, the last criterion to classify these tumors as refractory is ill defined. Silent corticotroph and null cell adenomas have been reported, albeit not in all studies, to be larger and recur more often compared with silent gonadotroph tumors. Nevertheless, it is currently unknown if certain NFPA subtypes are more often refractory using well defined criteria. The response rate to temozolomide is lower in NFPA compared to that seen in functioning tumors. Refractory NFPAs present a significant diagnostic and therapeutic challenge and are associated with increased morbidity and mortality rates.

ODP355 The analysis of tumor infiltrative lymphocytes in corticotroph adenomas and its relation to hormonal status

Abstract Background Corticotrophs are a well-known tissue susceptible to cytotoxicity by lymphocytes, as seen in autoimmune hypophysitis, suggesting that immunological approach may be one of the therapeutic strategies for ACTH-producing adenomas. However, the efficacy of immune therapy for general ACTH-producing adenomas remains unclear. And cortisol levels expected to affect the tumor microenvironment (TME). Objectives To clarify whether ACTH-producing adenomas are sensitive to immunotherapy and if this approach can be a potential treatment for these challenging tumors. Methods TME was examined by immunostaining using pituitary adenomas specimens. This study consists of two phases: In phase 1, TME of ACTH-producing adenomas (n=29) was analyzed by comparing with GH-producing pituitary adenomas (GHomas) (n=10) and nonfunctioning pituitary adenomas (NPAs) derived from gonadotrophs origin (Gnomas) (n=10). In phase 2, corticotroph adenomas were divided into three groups that were considered to be at different cortisol exposure; naïve ACTH-producing adenomas (Naïve, n=29), treatment with metyrapone (Met, n=13), and silent corticotroph adenomas (SCAs) (n=12). These TME were analyzed and compared. To detect T-lymphocytes and M2 macrophages, antibodies to CD3, 4, or 8, and CD163 were used, respectively. The association between TME and patients’ background data including urinary free cortisol levels were analyzed. Results Phase 1: Tumor infiltrating lymphocytes (TILs) evaluated by CD3 + cells inACTH-producing adenomas were less than those in the GHomas (p&amp;lt;0. 01) and lower tendency compare to Gnomas (p=0. 05). Among them, CD8 + cells in ACTH-producing adenomas were less than both (p&amp;lt;0. 01, p&amp;lt;0. 01, respectively). CD163 + cells were widely distributed in ACTH-producing adenomas but less than Gnomas (p&amp;lt;0. 01). The number of CD163 + cells were not associated with tumor aggressiveness or invasiveness in ACTH-producing adenomas. Phase 2: First, SCAs, NPAs from corticotroph origin were compared to Gnomas, showing that less CD8 + cells were detected in SCAs (p&amp;lt;0. 01), suggesting low CD8 + cells were common feature of corticotroph adenomas regardless of cortisol level. Among 3 groups of different cortisol exposure, CD4 + cells were higher both in Met and SCAs than in Naïve (p&amp;lt;0. 01, p=0. 01, respectively), while CD8+ cells were not altered. In contrast, the number of CD163+ cells were lower in Met than Naïve (p&amp;lt;0. 01), suggesting the association between cortisol levels and the number of CD163 + cells. Conclusions We revealed for the first time that low TILs are common features among corticotroph adenomas regardless cortisol levels. Moreover, the CD4 + cells but not CD8 + cells were higher in tumors with low cortisol status, suggesting induction of CD8 + cells are required for the immune therapy to corticotroph adenomas. Regarding with CD163 + cells, no association with tumor behavior was shown rather related to cortisol exposure status. Presentation: No date and time listed

LBODP079 A Case of Silent Invasive Corticotroph Adenoma

Abstract ACTH-secreting pituitary adenomas account for about two-thirds of cases of endogenous Cushing's syndrome and are considered the most common cause of endogenous hypercortisolemia. Silent corticotroph adenomas (SCAs) are pituitary tumors that stain positive for adrenocorticotropic hormone (ACTH) but do not produce biochemical levels of excess ACTH or cortisol. These tumors account for approximately 20% of all corticotroph adenomas and 5.5% of nonfunctioning pituitary adenomas. New immunohistochemical (IHC) techniques continue to be the gold standard in diagnosis, while having prognostic implications. Presentation: No date and time listed

ODP351 Silent Corticotroph Adenomas – Characteristics and Comparisons to Other Non-functioning Pituitary Adenomas: A Case Series

Abstract Introduction Silent corticotroph adenomas (SCA) are characterised by an absence of cortisol excess yet show positive immunostaining for T-Box transcription factor (TPIT) and frequently adrenocorticotropic hormone (ACTH). Patients with a SCA commonly present with symptoms of mass effect such as headache or visual compromise or are identified incidentally on imaging. SCAs are high risk according to the WHO 2017 classification scheme. Aim To assess our cohort of SCAs for differences in demographics, presenting symptoms and imaging results compared to other non-functioning pituitary adenomas (NFPA). Methods Surgically treated patients with NFPAs seen by endocrinology at an Australian Tertiary Centre between the years 2011-2021 were included in the analysis. SCA was diagnosed based on the absence of clinical and biochemical features of cortisol excess in combination with immunohistochemical staining including positive staining for ACTH. Other NFPA subtypes were defined by immunohistochemical staining and the absence of hormone overproduction. We compared demographic information, symptoms at presentation and tumour size as assessed by magnetic resonance imaging (MRI) between the SCA and all other NFPA groups. Where available, pre- and postoperative ACTH and cortisol levels were compared in the SCA and non-SCA groups. Results 31 patients were identified, 5 with SCA and 26 with other NFPA, all were macroadenomas. All 5 cases of SCA showed ACTH positivity, 2 of 5 cases were stained for TPIT, both were positive. Mean age at surgery for the SCA group was 50.8±10.9 years. Mean non-SCA age was 54.3±15.4 years. 3 of the 5 patients with SCA were women. The most frequent symptoms at presentation were headache (SCA: 40%; non-SCA 36%) and visual disturbances (SCA: 60%; non-SCA 68%). The mean maximal tumour diameter in the SCA group was 31.36±13.61 mm versus 24.65±6.80 mm in the non-SCA group on MRI. Cavernous sinus invasion was present in 60% of the SCA and 38.5% of the non-SCA group. In the SCA group pre-operative ACTH levels were 5.1±2.6 pmol/L (normal &amp;lt;12.1 pmol/L) and dropped to 2.5±1.8 pmol/L postoperatively. Cortisol levels were 344±205 nmol/L (normal 138-650 nmol/L) and dropped to 269±228 nmol/L. In the non-SCA group ACTH levels were 4.5±2.3 pmol/L preoperatively and 4.6±3.8 pmol/L postoperatively. Cortisol levels were and 538±168 nmol/L preoperatively and 403±179 nmol/L postoperatively. Conclusion In this retrospective comparison, compared to other NFPAs the SCA group showed younger age, more frequent headaches, less visual compromise, larger tumour size and increased cavernous sinus invasion. These findings are consistent with the known aggressiveness of SCAs. The reduction in ACTH levels postoperatively support the concept that SCAs produce inactive forms of ACTH. Although this is a small case series, there may be merit in monitoring for relative increases in ACTH levels in patients with a history of SCA. Presentation: No date and time listed

Quantitative Ubiquitinomics Revealed Abnormal Ubiquitinated ATP7A Involved in Down-Regulation of ACTH in Silent Corticotroph Adenomas.

Ubiquitination is reported to be a critical biological event on ACTH secretion in corticotroph adenomas. However, the effect of ubiquitylation on ACTH secretion in silent corticotroph adenomas (SCAs) remains unclear. The aim of our study was to explore the mechanism of decreased secretion of ACTH in SCAs with ubiquitinomics. The differently expressed ubiquitinated proteins between SCAs and functioning corticotroph adenomas (FCAs) were identified by 4D label-free mass spectrometer, followed by bioinformatics analysis. The function of the candidate ubiquitinated protein ATP7A (K333) was validated in AtT20 cells. A total of 111 ubiquitinated sites corresponding to 94 ubiquitinated proteins were typically different between SCAs and FCAs. Among all the ubiquitinated sites, 102 showed decreased ubiquitination in SCAs, which mapped to 85 ubiquitinated proteins. Pathway enrichment analysis revealed that ubiquitinated proteins were mainly enriched in vesicle pathway and protein secretion pathway. ATP7A (K333) was one of the proteins enriched in vesicle pathway and protein secretion pathway with decreased ubiquitination level in SCAs. In vitro assay indicated that both ATP7A siRNA and omeprazole (ATP7A protein inhibitor) increased the secretion of ACTH in AtT20 cell supernatant compared to control groups (p<0.05). These results indicated that ATP7A might be related to the abnormal expression of ACTH in SCAs and potential for the treatment of SCAs.

Difference in miRNA Expression in Functioning and Silent Corticotroph Pituitary Adenomas Indicates the Role of miRNA in the Regulation of Corticosteroid Receptors.

Corticotroph pituitary adenomas commonly cause Cushing’s disease (CD), but some of them are clinically silent. The reason why they do not cause endocrinological symptoms remains unclear. We used data from small RNA sequencing in adenomas causing CD (n = 28) and silent ones (n = 20) to explore the role of miRNA in hormone secretion and clinical status of the tumors. By comparing miRNA profiles, we identified 19 miRNAs differentially expressed in clinically functioning and silent corticotroph adenomas. The analysis of their putative target genes indicates a role of miRNAs in regulation of the corticosteroid receptors expression. Adenomas causing CD have higher expression of hsa-miR-124-3p and hsa-miR-135-5p and lower expression of their target genes NR3C1 and NR3C2. The role of hsa-miR-124-3p in the regulation of NR3C1 was further validated in vitro using AtT-20/D16v-F2 cells. The cells transfected with miR-124-3p mimics showed lower levels of glucocorticoid receptor expression than control cells while the interaction between miR-124-3p and NR3C1 3′ UTR was confirmed using luciferase reporter assay. The results indicate a relatively small difference in miRNA expression between clinically functioning and silent corticotroph pituitary adenomas. High expression of hsa-miR-124-3p in adenomas causing CD plays a role in the regulation of glucocorticoid receptor level and probably in reducing the effect of negative feedback mediated by corticosteroids.