Treatment of clinically nonfunctioning pituitary adenomas with dopamine agonists

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

BACKGROUND

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.

METHODS

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.

RESULTS

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).

CONCLUSIONS

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.

A Non-Secreting Pituitary Adenoma That Changed to a Prolactinoma

Pituitary adenomas (PAs) are the third most common brain tumors in adults right after meningiomas and gliomas. Taking into account their hormonal activity in vivo, they can be divided in functioning PAs, which secrete hormones, and nonfunctioning pituitary adenomas (NFPAs), which are not associated with increased hormone secretion. We present the case of a man diagnosed with pituitary apoplexy. A transsphenoidal surgery was performed with subtotal removal of the mass. Pituitary hormones were measured before and after the procedure on several occasions, showing always normal PRL values, so he was diagnosed with a clinically NFPA. Two years later, the patient noticed a visual deficit. A new magnetic resonance imaging study was performed, showing adenomatous recurrence, and the patient underwent a new surgery. After this, hormonal evaluation revealed high levels of PRL on several occasions. After treatment with cabergoline was started, PRL levels normalized, the visual deficit improved, and there was a slight adenoma reduction. This case report represents an exception to the paradigm that in the presence of a macroadenoma and normal PRL levels (avoiding the "hook effect"), a prolactinoma can be discarded. Moreover, it stresses the importance of comprehensive, regular, and lifelong surveillance of patients with NFPAs and the close monitoring of serum PRL.

Lanreotide versus placebo for tumour reduction in patients with a 68Ga-DOTATATE PET-positive, clinically non-functioning pituitary macroadenoma (GALANT study): a randomised, multicentre, phase 3 trial with blinded outcome assessment

Background

No established medical treatment options currently exist for patients with non-functioning pituitary macroadenoma (NFPMA). Somatostatin analogues may prevent tumour growth, but randomised controlled trials are lacking. In vivo somatostatin receptor assessment with 68Ga-DOTATATE PET could help in selecting patients for treatment. We aimed to determine the effect of the somatostatin analogue lanreotide on tumour size in patients with a 68Ga-DOTATATE PET-positive NFPMA.

Methods

The GALANT study was an investigator-initiated, multicentre, randomised, double-blind, placebo-controlled, parallel-group, phase 3 trial with recruitment at three academic hospitals in the Netherlands. Adult patients with a suprasellar extending NFPMA, either surgery-naïve or postoperative remnant ≥10 mm, were eligible for inclusion. Important exclusion criteria were previous sellar radiotherapy and use of dopamine receptor agonists. Somatostatin receptor expression in the NFPMA was determined through 68Ga-DOTATATE PET/CT, co-registered with MRI. A predefined sample of 44 patients with PET-positive NFPMA were randomly assigned (1:1) to lanreotide acetate 120 mg or placebo, both administered as deep subcutaneous injections every 28 days for 72 weeks. Primary outcome was the change in cranio-caudal tumour diameter measured on pituitary MRI from baseline to end-of-treatment in the intention-to-treat population. Participants, investigators and outcome assessors were masked to treatment allocation. The trial is registered with the Netherlands Trial Registry, NL5136, and EudraCT, 2015-001234-22.

Findings

Between Nov 3, 2015, and Dec 10, 2019, 49 patients were included in the study. Forty-four patients with a 68Ga-DOTATATE PET-positive NFPMA were randomly assigned to lanreotide (22 [50%]) or placebo (22 [50%]). Study treatment was completed in 13 (59%) lanreotide and 19 (86%) placebo participants. The mean (SD) change from baseline in cranio-caudal tumour diameter after treatment was +1·2 (2·5) mm with lanreotide and +1·3 (1·5) mm with placebo; adjusted mean difference versus placebo -0·1 mm (95% CI -1·3 to 1·2, p = 0·93). Adverse events occurred in 22 (100%, 147 events) lanreotide and 21 (95%, 94 events) placebo participants. Gastrointestinal complaints were most common, reported by 18 (82%) lanreotide and 8 (36%) placebo participants. There were no treatment-related serious adverse events.

Interpretation

Compared with placebo, lanreotide treatment did not reduce tumour size or growth in patients with 68Ga-DOTATATE PET-positive NFPMA.

Funding

Ipsen Farmaceutica BV.

Consensus guideline for the diagnosis and management of pituitary adenomas in childhood and adolescence: Part 2, specific diseases

Pituitary adenomas are rare in children and young people under the age of 19 (hereafter referred to as CYP) but they pose some different diagnostic and management challenges in this age group than in adults. These rare neoplasms can disrupt maturational, visual, intellectual and developmental processes and, in CYP, they tend to have more occult presentation, aggressive behaviour and are more likely to have a genetic basis than in adults. Through standardized AGREE II methodology, literature review and Delphi consensus, a multidisciplinary expert group developed 74 pragmatic management recommendations aimed at optimizing care for CYP in the first-ever comprehensive consensus guideline to cover the care of CYP with pituitary adenoma. Part 2 of this consensus guideline details 57 recommendations for paediatric patients with prolactinomas, Cushing disease, growth hormone excess causing gigantism and acromegaly, clinically non-functioning adenomas, and the rare TSHomas. Compared with adult patients with pituitary adenomas, we highlight that, in the CYP group, there is a greater proportion of functioning tumours, including macroprolactinomas, greater likelihood of underlying genetic disease, more corticotrophinomas in boys aged under 10 years than in girls and difficulty of peri-pubertal diagnosis of growth hormone excess. Collaboration with pituitary specialists caring for adult patients, as part of commissioned and centralized multidisciplinary teams, is key for optimizing management, transition and lifelong care and facilitates the collection of health-related quality of survival outcomes of novel medical, surgical and radiotherapeutic treatments, which are currently largely missing.

Clinical and Molecular Characteristics of Gonadotroph Pituitary Tumors According to the WHO Classification

Since 2017, hormone-negative pituitary neuroendocrine tumors expressing the steroidogenic factor SF1 have been recognized as gonadotroph tumors (GnPT) but have been poorly studied. To further characterize their bio-clinical spectrum, 54 GnPT defined by immunostaining for FSH and/or LH (group 1, n = 41) or SF1 only (group 2, n = 13) were compared and studied for SF1, βFSH, βLH, CCNA2, CCNB1, CCND1, caspase 3, D2R, and AIP gene expression by qRT-PCR. Immunohistochemistry for AIP and/or D2R was performed in representative cases. Overall, patients were significantly younger in group 1 (P = 0.040 vs group 2), with a similar trend excluding recurrent cases (P = 0.078), and no significant difference in gender, tumor size, invasion or Ki67. SF1 expression was similar in both groups but negatively correlated with the patient's age (P = 0.013) and positively correlated with βLH (P < 0.001) expression. Beta-FSH and AIP were significantly higher in group 1 (P = 0.042 and P = 0.024, respectively). Ki67 was unrelated to gonadotroph markers but positively correlated with CCNB1 (P = 0.001) and negatively correlated with CCND1 (P = 0.008). D2R and AIP were strongly correlated with each other (P < 0.001), and both positively correlated with SF1, βFSH, βLH, and CCND1. AIP immunopositivity was frequently observed in both groups, with a similar median score, and unrelated to Ki67. D2R immunostaining was best detected with a polyclonal antibody and mostly cytoplasmic. This study indicates that hormone-negative GnPT tend to occur in older patients but do not significantly differ from other GnPT in terms of invasion or proliferation. It also points out the current limits of D2R immunostaining in such tumors.

Cabergoline treatment for surgery-naïve non-functioning pituitary macroadenomas

PURPOSE

The treatment strategy of non-functioning pituitary adenomas (NFPAs) includes surgery, radiotherapy, medical therapy, or observation without intervention. Cabergoline, a dopaminergic agonist, was suggested for the treatment of NFPA remnants after trans-sphenoidal surgery. This study investigates the efficacy of cabergoline in surgery-naive patients with NFPA.

METHODS

Retrospective cohort study including surgery-naive patients with NFPA ≥ 10 mm, treated with cabergoline at a dose of ≥ 1 mg/week for at least 24 months. Patients with chiasmal damage were excluded. Data collected included symptoms, in particular visual disturbances, hormonal levels, tumor characteristics and size evaluated by MRI. Tumor growth was defined as an increase in maximal diameter of ≥  2 mm, and shrinkage as reduction of ≥ 2 mm.

RESULTS

Our cohort included 25 patients treated with cabergoline as primary therapy. Mean age was 63.3 ± 17.3 years, 56% (14/25) were males. Mean tumor size at diagnosis was 18.6 ± 6.3 mm (median 17 mm, range 10-36), and the average follow-up period with cabergoline was 4.6 ± 3.4 years. Out of the 25 tumors, five tumors (20%) decreased in size (mean decrease of 5.0 ± 3.0 mm), 12 tumors (48%) remained stable, and eight (32%) increased in size (mean growth of 5.0 ± 3.3 mm) with cabergoline treatment. During the first two years of cabergoline treatment, the median tumor size exhibited a reduction of 0.5 mm. Patients with an increase in tumor size had larger adenomas at diagnosis and a longer follow-up. Two patients (8%) underwent surgery due to tumor enlargement.

CONCLUSION

Primary treatment with cabergoline is a reasonable approach for selected patients with NFPAs without visual threat.

Aggressive and Metastatic Pituitary Neuroendocrine Tumors: Therapeutic Management and Off-Label Drug Use

Pituitary neuroendocrine tumors (PitNETs) are the most common pituitary tumors and the second most common brain tumors. Although the vast majority (>90%) are benign, a small percentage (<2%) are aggressive. These aggressive PitNETs (AgPitNETs) are defined by the presence of radiological invasion, a high rate of cell proliferation, resistance to conventional treatments, and/or a high propensity for recurrence. Lastly, there are the rare pituitary carcinomas, also known as metastatic PitNETs (MetPitNETs), which account for only 0.2% of cases and are defined by the presence of craniospinal or distant metastases. At present, there are no definitive factors that allow us to predict with certainty the aggressive behavior of PitNETs, making the therapeutic management of AgPitNETs a real challenge. Surgery is considered the first-line treatment for AgPitNETs and MetPitNETs. Radiation therapy can be effective in controlling tumor growth and regulating hormone hypersecretion. Currently, there are no approved non-endocrine medical therapies for the management of AgPitNETs/MetPitNETs, mainly due to the lack of randomized controlled clinical trials. As a result, many of the medical therapies used are off-label drugs, and several are under investigation. Temozolomide (TMZ) is now recognized as the primary medical treatment following the failure of standard therapy (medical treatment, surgery, and radiotherapy) in AgPitNETs/MetPitNETs due to its ability to improve overall and progression-free survival rates in responding patients over 5 years. Other therapeutic options include pituitary-targeted therapies (dopamine agonists and somatostatin analogs), hormonal antisecretory drugs, non-hormonal targeted therapies, radionuclide treatments, and immunotherapy. However, the number of patients who have undergone these treatments is limited, and the results obtained to date have been inconsistent. As a result, it is imperative to expand the cohort of patients undergoing treatment to better determine the therapeutic efficacy and safety of these drugs for individuals with AgPitNETs/MetPitNETs.

Pharmacological Treatment of Non-Functioning Pituitary Adenomas

Treatment strategies for NFPA include surgery, radiotherapy, medical treatment, or follow-up. The treatment of NFPAs with compressive symptoms is surgical. However, in case of post-surgical tumor remnants, there may be treatment strategies that include observation and radiotherapy. Recently, medical treatment with cabergoline (CAB) has been recommended to contain and/or reduce the size of the tumor remnant. Based on the findings that many NFPAs show a dopamine receptor (DR) and somatostatin receptor (SR) expression, medical therapy with dopamine agonists (DAs) and somatostatin receptor ligands (SSRLs) has been tested as an alternative to prevent recurrence after surgery. The DAs have been the most extensively studied, showing some potential in terms of tumor shrinkage. SSRLs and other emerging medical options are much less studied. We will review and critically evaluate the current data on the medical therapy of NFPAs to elucidate their role in the management of this tumor type. In the case of actively growing remnants (more than 10% growth per year) and high-risk pituitary adenomas, treatment with CAB at a dose of 1.5-3.0 mg is indicated for tumor containment and/or reduction. In relation to combined chemotherapy with CAB, there is little information in the literature to support its use. In our experience, CAB treatment can be used after radiotherapy as an adjuvant treatment.

Clinical Significance of T2-Weighted Sequence Intensity on Magnetic Resonance Imaging in Clinically Non-Functioning Pituitary Adenomas

BACKGROUND

Little is known about the relationship between signal intensity patterns on T2-weighted magnetic resonance imaging (MRI) in non-functioning pituitary adenomas (NFPAs).

OBJECTIVE

In this study, the clinical, hormonal, histological features, and therapeutic responses were evaluated according to the T2 signal intensity in NFPAs.

METHODS

This retrospective and multicenter study included a group of 166 NFPA patients (93 men, 56%, mean age 58.5 ±14.8 yr).

RESULTS

Approximately half of the tumors (n=84, 50.6%) were hyperintense, while 34.3% (n=57) and 15.1% (n=25) were iso- and hypointense, respectively. The median maximum tumor diameter of the isointense group [16 (13-25) mm] was significantly lower than that of the hyperintense [23 (16.6-29.7) mm] group (p=0.003). Similarly, the tumor volume of the isointense group [1,523 (618-5,226) mm3] was significantly lower than that of the hyperintense [4,012 (2,506-8,320) mm3] group (p=0.002). Chiasmatic compression occurred less frequently in tumors with isointense signal characteristics (38.6%) compared to tumors with hypointense (68%) and hyperintense (65.5%) signal characteristics (p=0.003). Invasive adenomas (p=0.001) and the degree of cavernous sinus invasion (p<0.001) were more frequent in the hyperintense adenoma group compared to the remaining groups. Plurihormonal tumors and silent lactotroph adenomas were more frequent in the isointense tumor group.

CONCLUSION

In conclusion, hyperintensity on T2-weighted MRI in NFPAs is associated with larger and more invasive tumors compared to isointense NFPAs.

Update on Current Evidence for the Diagnosis and Management of Nonfunctioning Pituitary Neuroendocrine Tumors

Pituitary neuroendocrine tumors (PitNETs) are the third most frequently diagnosed intracranial tumors, with nonfunctioning PitNETs (nfPitNETs) accounting for 30% of all pituitary tumors and representing the most common type of macroPitNETs. NfPitNETs are usually benign tumors with no evidence of hormone oversecretion except for hyperprolactinemia secondary to pituitary stalk compression. Due to this, they do not typically present with clinical syndromes like acromegaly, Cushing's disease or hyperthyroidism and instead are identified incidentally on imaging or from symptoms of mass effects (headache, vision changes, apoplexy). With the lack of effective medical interventions, first-line treatment is transsphenoidal surgical resection, however, nfPitNETs often have supra- or parasellar extension, and total resection of the tumor is often not possible, resulting in residual tumor regrowth or reoccurrence. While functional PitNETs can be easily followed for recurrence using hormonal biomarkers, there is no similar parameter to predict recurrence in nfPitNETs, hence delaying early recognition and timely management. Therefore, there is a need to identify prognostic biomarkers that can be used for patient surveillance and as therapeutic targets. This review focuses on summarizing the current evidence on nfPitNETs, with a special focus on potential new biomarkers and therapeutics.

A β-Arrestin 2-Biased Dopamine Receptor Type 2 (DRD2) Agonist Is More Efficacious Than Cabergoline in Reducing Cell Proliferation in PRL-Secreting but Not in Non-Functioning Pituitary Tumor Cells

The molecular events underlying the variable effectiveness of dopamine receptor type 2 (DRD2) agonists in pituitary neuroendocrine tumors (PitNETs) are not known. Besides the canonical pathway induced by DRD2 coupling with Gi proteins, the β-arrestin 2 pathway contributes to DRD2's antimitotic effects in PRL- and NF-PitNETs. A promising pharmacological strategy is the use of DRD2-biased agonists that selectively activate only one of these two pathways. The aim of the present study was to compare the effects of two biased DRD2 ligands, selectively activating the G protein (MLS1547) or β-arrestin 2 (UNC9994) pathway, with unbiased DRD2 agonist cabergoline in PRL- and NF-PitNET cells. In rat tumoral pituitary PRL-secreting MMQ cells, UNC9994 reduced cell proliferation with a greater efficacy compared to cabergoline (-40.2 ± 20.4% vs. -21 ± 10.9%, p < 0.05), whereas the G-protein-biased agonist induced only a slight reduction. β-arrestin 2 silencing, but not pertussis toxin treatment, reverted UNC9994 and cabergoline's antiproliferative effects. In a cabergoline-resistant PRL-PitNET primary culture, UNC9994 inhibited cell proliferation and PRL release. In contrast, in NF-PitNET primary cultures (n = 23), biased agonists did not show better antiproliferative effects than cabergoline. In conclusion, the preferential activation of the β-arrestin 2 pathway by UNC9994 improves DRD2-mediated antiproliferative effects in PRL-PitNETs, suggesting a new pharmacological approach for resistant or poorly responsive tumors.

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.

Natural history of nonfunctioning pituitary macroadenomas followed without intervention: A retrospective cohort study

OBJECTIVE

The treatment strategy for nonfunctioning pituitary adenomas (NFPA) includes surgery, radiotherapy, medical treatment, or follow-up. Prior series of patients with NFPAs followed without intervention include small numbers of patients with macroadenomas. This study investigated the natural history of patients with macroadenomas followed without treatment.

DESIGN AND PATIENTS

Retrospective cohort study included patients>18 years, with a diagnosis of NFPA ≥ 10 mm who were naïve to surgery or medical treatment and followed more than 12 months after diagnosis. Patients with chiasmal threat were excluded. Follow-up terminated if the patient underwent surgery, received cabergoline or was lost to follow-up.

MEASUREMENTS

Data collected included evaluation of tumour characteristics and size by MRI, symptoms including visual disturbances, and hormonal levels. Tumour growth was defined as maximal diameter increase of ≥2 mm.

RESULTS

The cohort included 49 patients (30 males, mean age 68.0 ± 12.0 years). At diagnosis, the average tumour size was 17.8 ± 5.9 mm. Mean follow-up time was 4.9 ± 4.9 years. Increase in tumour size occurred in 16 patients (33%), with an average growth of 5.1 ± 4.4 mm. Reduction in tumour size occurred in 10 patients (20%), with a mean decrease of 3.5 ± 1.3 mm. Twenty-three patients remained with stable tumours. Overall, 33 patients (67%) were observed without any intervention; 3 patients were operated and 13 were treated with cabergoline. None of the parameters including age, gender, baseline tumour size, invasiveness, visual disturbances, or hypopituitarism at diagnosis, predicted tumour growth.

CONCLUSION

Observation of NFPAs without surgery or medical therapy is a reasonable approach in selected patients. In our study, no parameter predicted tumour growth.

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

Introduction

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.

Methods

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.

Results

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.

Conclusion

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.

Current medical treatment and perspective in gonadotroph tumors

Gonadotroph cell adenoma is the most common clinically nonfunctioning pituitary adenoma; and is pathologically defined by immunopositivity for SF-1, GATA2 and ER-α. Most tumors also stain for follicle stimulating hormone and luteinizing hormone β-subunits, but are usually hormonally silent and discovered incidentally or due to local mass effects. Complete transsphenoidal resection should be attempted when surgery is indicated. Post-surgical treatment can include radiation of the tumor remnant and medical treatment. Among medical treatments, dopamine agonists show the best evidence for preventing the need for recurrent surgery or radiation, and should be considered in patients with relatively bulky remnants or who have high risk features associated with tumor progression. Temozolomide is indicated for aggressive adenomas and carcinomas. Less well-established treatments include somatostatin receptor ligands, peptide receptor radionucleotide therapy and immunomodulatory agents.

Treatment of non-functioning pituitary adenoma with cabergoline: a systematic review and meta-analysis

PURPOSE

To make a systematic review and meta-analysis of studies evaluating the effect of cabergoline (CBG) in the treatment of non-functioning pituitary adenomas (NFPAs).

METHODS

The primary outcome was tumor shrinkage, using as cut-off a reduction of at least 20% of the NFPA size from baseline. The secondary outcomes were prevention of tumor progression, clinically required additional interventions and adverse events (AE). Search strategies were applied to MEDLINE, EMBASE, LILACS and CENTRAL. Independent reviewers assessed the study eligibility, extracted data, and evaluated risk of bias. Random meta-analysis for the proportion of tumor shrinkage, prevention of tumor progression, clinically required additional interventions and frequency of AE were conducted.

RESULTS

Five studies were included. The meta-analysis of proportion was 19% for tumor shrinkage (95% CI 8-38%, 4 studies, 108 participants), 50% for prevention of tumor progression (95% CI 35-64%, 5 studies, 187 participants), 14% for clinically required additional interventions (95% CI 6-30%, 4 studies, 128 participants) and 2% for adverse events (95% CI 1-6%, 3 studies, 157 participants).

CONCLUSIONS

Effect of CBG to promote tumor shrinkage in NFPAs was low, while prevention of tumor progression after surgery was seen in half of the cases, with a low frequency of adverse events.

SYSTEMATIC REVIEW REGISTRATION

PROSPERO CRD42020206778.

Efficacy of cabergoline therapy in patients with non-functioning pituitary adenomas: A single center clinical experience

Introduction

To evaluate the response to cabergoline (CBG) treatment in patients with non-functioning pituitary adenomas (NFPA).

Subjects and methods

Retrospective, single tertiary care center study. A total of 44 patients were treated with 3 mg/week of CBG, 32 after surgical treatment (transsphenoidal surgery [TSS] in 27 and TC in 5 patients) and 12 as primary therapy. Mean age was 59.2 ± 12 years and 23 (52.2%) were women. Response to therapy was ascertained by serial magnetic resonance imaging. The median duration of CBG therapy was 30 months (IQR 24-48). Response to CBG therapy was defined as a greater than 20% reduction in tumor size and volume.

Results

A significant reduction in tumor size was documented in 29 patients (66%), whereas in 11 patients (25%) the tumor increased in size and in 4 (9%), it remained stable. Significant tumor shrinkage was documented in 4 (33.3%) of 12 patients treated primarily and in 23 (71.8%) of those treated secondarily. The three-year progression-free survival was 0.61.

Conclusion

Cabergoline therapy is effective in reducing tumor growth in over two thirds of patients with NFPA, however 16% of patients will escape to this beneficial effect and will require alternative forms of treatment to halt tumor progression.

Development and Validation of a Prognostic Model for Post-Operative Recurrence of Pituitary Adenomas

Background

We aimed to assess clinical factors associated with tumor recurrence and build a nomogram based on identified risk factors to predict postoperative recurrence in patients with pituitary adenomas (PAs) who underwent gross-total resection (GTR).

Methods

A total of 829 patients with PAs who achieved GTR at Tongji Hospital between January 2013 and December 2018 were included in this retrospective study. The median follow-up time was 66.7 months (range: 15.6-106.3 months). Patients were randomly divided into training (n = 553) or validation (n = 276) cohorts. A range of clinical characteristics, radiological findings, and laboratory data were collected. Uni- and multivariate Cox regression analyses were applied to determine the potential risk factors for PA recurrence. A nomogram model was built from the identified factors to predict recurrence. Concordance index (C-index), calibration curve, and receiver operating characteristic (ROC) were used to determine the predictive accuracy of the nomogram. Decision curve analysis (DCA) was performed to evaluate the clinical efficacy of the nomogram.

Results

Pseudocapsule-based extracapsular resection (ER), cavernous sinus invasion (CSI), and tumor size were included in the nomogram. C-indices of the nomogram were 0.776 (95% confidence interval [CI]: 0.747-0.806) and 0.714 (95% CI: 0.681-0.747) for the training and validation cohorts, respectively. The area under the curve (AUC) of the nomogram was 0.770, 0.774, and 0.818 for 4-, 6-, 8-year progression-free survival (PFS) probabilities in the training cohort, respectively, and 0.739, 0.715 and 0.740 for 4-, 6-, 8-year PFS probabilities in the validation cohort, respectively. Calibration curves were well-fitted in both training and validation cohorts. DCA revealed that the nomogram model improved the prediction of PFS in both cohorts.

Conclusions

Pseudocapsule-based ER, CSI, and tumor size were identified as independent predictors of PA recurrence. In the present study, we developed a novel and valid nomogram with potential utility as a tool for predicting postoperative PA recurrence. The use of the nonogram model can facilitate the tailoring of counseling to meet the individual needs of patients.

Prognostic Factors for Recurrence in Pituitary Adenomas: Recent Progress and Future Directions

Pituitary adenomas (PAs) are benign lesions; nonetheless, some PAs exhibit aggressive behaviors, which lead to recurrence. The impact of pituitary dysfunction, invasion-related risks, and other complications considerably affect the quality of life of patients with recurrent PAs. Reliable prognostic factors are needed for recurrent PAs but require confirmation. This review summarizes research progress on two aspects—namely, the clinical and biological factors (biomarkers) for recurrent PAs. Postoperative residue, age, immunohistological subtypes, invasion, tumor size, hormone levels, and postoperative radiotherapy can predict the risk of recurrence in patients with PAs. Additionally, biomarkers such as Ki-67, p53, cadherin, pituitary tumor transforming gene, matrix metalloproteinase-9, epidermal growth factor receptor, fascin actin-bundling protein 1, cyclooxygenase-2, and some miRNAs and lncRNAs may be utilized as valuable tools for predicting PA recurrence. As no single marker can independently predict PA recurrence, we introduce an array of comprehensive models and grading methods, including multiple prognostic factors, to predict the prognosis of PAs, which have shown good effectiveness and would be beneficial for predicting PA recurrence.

Past, Present, and Future of Therapies for Pituitary Neuroendocrine Tumors: Need for Omics and Drug Repositioning Guidance

Innovation roadmaps are important, because they encourage the actors in an innovation ecosystem to creatively imagine multiple possible science future(s), while anticipating the prospects and challenges on the innovation trajectory. In this overarching context, this expert review highlights the present unmet need for therapeutic innovations for pituitary neuroendocrine tumors (PitNETs), also known as pituitary adenomas. Although there are many drugs used in practice to treat PitNETs, many of these drugs can have negative side effects and show highly variable outcomes in terms of overall recovery. Building innovation roadmaps for PitNETs' treatments can allow incorporation of systems biology approaches to bring about insights at multiple levels of cell biology, from genes to proteins to metabolites. Using the systems biology techniques, it will then be possible to offer potential therapeutic strategies for the convergence of preventive approaches and patient-centered disease treatment. Here, we first provide a comprehensive overview of the molecular subtypes of PitNETs and therapeutics for these tumors from the past to the present. We then discuss examples of clinical trials and drug repositioning studies and how multi-omics studies can help in discovery and rational development of new therapeutics for PitNETs. Finally, this expert review offers new public health and personalized medicine approaches on cases that are refractory to conventional treatment or recur despite currently used surgical and/or drug therapy.

Exosomal miRNA Profiling is a Potential Screening Route for Non-Functional Pituitary Adenoma

Non-functional pituitary adenomas (NFPAs) are one of the most prevalent pituitary adenoma subtypes. The lack of reliable screening approach for NFPAs for the insidious clinical course usually leads to delays in medical therapy and consequently worse prognosis. Hence, we employed a sequence cohort (patient: control, 6:2) and a validation cohort (patient: control, 22:8) to develop a serum exosomal miRNA profile-based method for NFPA screening and prognosis prediction. We found that a total of 1,395 kinds of human miRNA were detected. Compared with healthy donors, 18 up-regulated and 36 down-regulated miRNAs showed significant expression alterations in NFPA patients. Target genes of differentially expressed miRNAs are mainly enriched in axonogenesis and cancer-associated terms. After validation, hsa-miR-486-5p, hsa-miR-151a-5p, hsa-miR-652-3p_R+1, and hsa-miR-1180-3p were promising biomarkers for NFPA, in which miR-486-5p was the most competent one. After a median of 33 months of prospective follow-up, exosomal hsa-miR-486-5p also was an efficient predictive biomarker for progression or relapse of NFPAs. By protein-protein interaction network construction of hsa-miR-486-5p targeted genes, the core modules revealed a high possibility that exosomal hsa-miR-486-5p regulated tumor progression by epigenetic regulation of MAPK signaling pathways. In conclusion, exosomal hsa-miR-486-5p, hsa-miR-151a-5p, hsa-miR-652-3p_R+1, and hsa-miR-1180-3p are candidate biomarkers for diagnosis and screening of NFPAs. More importantly, prospective follow-up reveals that hsa-miR-486-5p can be regarded as a significant predictor for prognosis of NFPAs.

DRD2 Agonist Cabergoline Abolished the Escape Mechanism Induced by mTOR Inhibitor Everolimus in Tumoral Pituitary Cells

The mammalian target of rapamycin (mTOR) inhibitor everolimus has been shown to display antiproliferative effects on a wide spectrum of tumors. In vitro studies demonstrated that everolimus inhibited pituitary neuroendocrine tumor (PitNET) cell growth in a subset of patients. Sensitivity to everolimus is reduced by an escape mechanism that increases AKT phosphorylation (p-AKT), leading to pro-survival pathway activation. Dopamine receptor type 2 (DRD2) mediates a reduction of p-AKT in a subgroup of non-functioning PitNETs (NF-PitNETs) and in prolactin-secreting tumor cells (MMQ cells) through a β-arrestin 2-dependent mechanism. The aim of this study was to investigate the efficacy of everolimus combined with DRD2 agonist cabergoline in reducing NF-PitNET primary cells and MMQ cell proliferation and to evaluate AKT phosphorylation and a possible role of β-arrestin 2. We found that 9 out of 14 NF-PitNETs were resistant to everolimus, but the combined treatment with cabergoline inhibited cell proliferation in 7 out of 9 tumors (-31.4 ± 9.9%, p < 0.001 vs. basal) and reduced cyclin D3 expression. In the everolimus-unresponsive NF-PitNET group, everolimus determined a significant increase of p-AKT/total-AKT ratio (2.1-fold, p < 0.01, vs. basal) that was reverted by cabergoline cotreatment. To investigate the molecular mechanism involved, we used MMQ cells as a model of everolimus escape mechanism. Indeed everolimus did not affect MMQ cell proliferation and increased the p-AKT/total-AKT ratio (+1.53 ± 0.24-fold, p < 0.001 vs. basal), whereas cabergoline significantly reduced cell proliferation (-22.8 ± 6.8%, p < 0.001 vs. basal) and p-AKT. The combined treatment of everolimus and cabergoline induced a reduction of both cell proliferation (-34.8 ± 18%, p < 0.001 vs. basal and p < 0.05 vs. cabergoline alone) and p-AKT/total-AKT ratio (-34.5 ± 14%, p < 0.001 vs. basal and p < 0.05 vs. cabergoline alone). To test β-arrestin 2 involvement, silencing experiments were performed in MMQ cells. Our data showed that the lack of β-arrestin 2 prevented the everolimus and cabergoline cotreatment inhibitory effects on both p-AKT and cell proliferation. In conclusion, this study revealed that cabergoline might overcome the everolimus escape mechanism in NF-PitNETs and tumoral lactotrophs by inhibiting upstream AKT activation. The co-administration of cabergoline might improve mTOR inhibitor antitumoral activity, paving the way for a potential combined therapy in β-arrestin 2-expressing NF-PitNETs or other PitNETs resistant to conventional treatments.

Targeting Aggressive Pituitary Adenomas at the Molecular Level-A Review

Pituitary adenomas (PAs) are mostly benign endocrine tumors that can be treated by resection or medication. However, up to 10% of PAs show an aggressive behavior with invasion of adjacent tissue, rapid proliferation, or recurrence. Here, we provide an overview of target structures in aggressive PAs and summarize current clinical trials including, but not limited to, PAs. Mainly, drug targets in PAs are based on general features of tumor cells such as immune checkpoints, so that programmed cell death 1 (ligand 1) (PD-1/PD-L1) targeting may bear potential to cure aggressive PAs. In addition, epidermal growth factor receptor (EGFR), mammalian target of rapamycin (mTOR), vascular endothelial growth factor (VEGF), fibroblast growth factor (FGF) and their downstream pathways are triggered in PAs, thereby modulating tumor cell proliferation, migration and/or tumor angiogenesis. Temozolomide (TMZ) can be an effective treatment of aggressive PAs. Combination of TMZ with 5-Fluorouracil (5-FU) or with radiotherapy could strengthen the therapeutic effects as compared to TMZ alone. Dopamine agonists (DAs) are the first line treatment for prolactinomas. Dopamine receptors are also expressed in other subtypes of PAs which renders DAs potentially suitable to treat other subtypes of PAs. Furthermore, targeting the invasive behavior of PAs could improve therapy. In this regard, human matrix metalloproteinase (MMP) family members and estrogens receptors (ERs) are highly expressed in aggressive PAs, and numerous studies demonstrated the role of these proteins to modulate invasiveness of PAs. This leaves a number of treatment options for aggressive PAs as reviewed here.

Current opinion on the diagnosis and management of non-functioning pituitary adenomas

INTRODUCTION

Non-functioning pituitary adenomas (NFPAs) are clinically silent tumors and the second most common pituitary adenoma. Surgery is the mainstay of treatment as there is, as yet, no effective medical treatment.

AREAS COVERED

We present current knowledge on the clinical diagnosis, histopathological classification, molecular data, and management strategies in NFPA.

EXPERT OPINION

NFPA is a heterogeneous group of tumors, in respect to their origin and clinical course. In recent years, research on pathology and molecular biology have advanced our knowledge of NFPA pathogenesis. NFPA exhibit, in the majority of cases, an indolent behavior, with satisfactory response to treatment. In aggressive cases, multimodal management is needed; however, even this approach may be insufficient, so the development of new treatments is warranted for better management. In this setting, the understanding of the mechanisms involved in the genesis and progression of NFPA is crucial for the identification and development of directed treatments with higher chances of response.

Clinically non-functioning pituitary adenomas

Clinically non functioning pituitary adenomas (NFPAs) include all pituitary adenomas that are not hormonally active. They are not associated with clinical syndromes such as amenorrhea-galactorrhea (prolactinomas), acromegaly, Cushing's disease or hyperthyroidism (TSH-secreting adenomas) and are therefore usually diagnosed by signs and symptoms related to a mass effect (headache, visual impairment, sometimes pituitary apoplexy), but also incidentally. Biochemical work up often documents several pituitary insufficiencies. In histopathology, the majority of NFPAs are gonadotroph. In the absence of an established medical therapy, surgery is the mainstay of treatment, unless contraindicated or in particular situations (e.g. small incidentalomas, distance from optic pathways). Resection, generally via a trans-sphenoidal approach (with the help of an endoscope), should be performed by a neurosurgeon with extensive experience in pituitary surgery, in order to maximize the chances of complete resection and to minimize complications. If a tumor remnant persists, watchful waiting is preferred to routine radiotherapy, as long as the tumor residue does not grow and is distant from the optic pathways. NFPA can sometimes recur even after complete resection, but predicting the individual risk of tumor remnant progression is difficult. Postoperative irradiation is only considered in case of residual tumor growth or relapse, due to its potential side effects.

Association of PTTG1 expression with invasiveness of non-functioning pituitary adenomas

Background

Pituitary tumor transforming gene 1 (PTTG1), paired-like homeodomain 2 (PITX2), and galectin-3 have been widely studied as predictive biomarkers for various tumors and are involved in tumorigenesis and tumor progression. We evaluated the usefulness of PTTG1, PITX2, and galectin-3 as predictive biomarkers for invasive non-functioning pituitary adenomas (NFPAs) by determining the relationship between the expressions of these three proteins and the invasiveness of the NFPAs. We also investigated whether PTTG1, E-cadherin, and Ki-67, which are known to be related to each other, show a correlation with NFPA features.

Methods

A retrospective study was conducted on 87 patients with NPFAs who underwent surgical removal. The NFPAs were classified into three groups based on magnetic resonance imaging findings of suprasellar extension and cavernous sinus invasion. Immunohistochemical staining for PTTG1, PITX2, galectin-3, E-cadherin, and Ki-67 was performed on tissue microarrays.

Results

PTTG1 expression showed a statistically significant correlation with the invasiveness of NFPAs, whereas PITX2 and galectin-3 did not have a relationship with the invasiveness of NFPAs. Moreover, there was no association among PTTG1, E-cadherin, and Ki-67 expression.

Conclusion

PTTG1 has the potential to serve as a predictive biomarker for invasive NFPA. Furthermore, this study may serve as a reference for the development of PTTG1-targeted therapeutic agents.

Potential biomarkers of miRNA in non-functional pituitary adenomas

BACKGROUND

The abnormal expression of microRNA (miRNA) has been proved to be closely related to the occurrence and progression of tumors. A unique expression of multiple miRNAs has been found in different types of tumors. However, the correlation between miRNA and non-functional pituitary adenoma (NFPA) is not clear. In this study, miRNAs (miRNA-26b, miRNA-138, miRNA-206, and miRNA-let-7e) have been used as detection genes to compare the miRNA expression levels of NFPA subjects and healthy controls and to explore the expression of four different miRNAs in NFPA.

METHODS

Ten untreated NFPA volunteers were served as subjects, and 10 normal subjects were selected as controls. Peripheral blood samples were collected, and four differentiated expressed miRNAs (miRNA-26b, miRNA-138, miRNA-206, and miRNA-let-7e) obtained in the early stage of the test group were detected, recorded, and archived by quantitative real-time PCR (qPCR). The difference and significance of endogenous miRNA expressions were explored through statistical analysis, hoping to find biomarkers for clinical treatment.

RESULTS

The levels of miRNA-26b, miRNA-138, miRNA-206, and miRNA-let-7e in the peripheral serum of patients with NFPA were significantly lower than those in normal subjects (P < 0.05).

CONCLUSION

miRNA-26b, miRNA-138, miRNA-206, and miRNA-let-7e may be involved in the occurrence and progress of NFPAs. This study aims to study the biological targets of NFPA. It starts from the study of whether miRNA, miRNA-26b, miRNA-138, miRNA-206, and miRNA-let-7e may be tumor suppressor genes in NFPA, which provides a basis for further exploration of tumor markers of pituitary adenoma.

Towards precision medicine for clinically non-functioning pituitary tumours

OBJECTIVE

Clinically non-functioning pituitary tumours (NFPT) are a heterogenous group of neoplasms with diverse outcomes. The purpose of this narrative review was to summarize available data on predictive factors, both in routine practice and research settings.

DESIGN

A literature review was conducted for papers published in peer-reviewed journals, investigating clinical, radiological, pathological and genetic predictive factors in NFPT.

RESULTS

Several clinical and radiological factors have been associated with NFPT recurrence and/or aggressiveness, including larger size and pre-/post-operative growth rates. Application of transcription factor immunohistochemistry has given rise to improved subtype identification, including 'higher-risk' subtypes, in routine clinical practice. Numerous other pathological and genetic biomarkers have demonstrated promise for prognostication in the research setting.

CONCLUSION

NFPT are a heterogenous group of tumours, characterized by diverse presentation, pathogenesis and outcomes. Ongoing refinements in understanding of tumour biology are likely to pave the way to improved integrative prognostication and precision medicine for NFPT.

Drug resistance in pituitary tumours: from cell membrane to intracellular signalling

The pharmacological treatment of pituitary tumours is based on the use of stable analogues of somatostatin and dopamine. The analogues bind to somatostatin receptor types 2 and 5 (SST2 and SST5) and dopamine receptor type 2 (DRD2), respectively, and generate signal transduction cascades in cancerous pituitary cells that culminate in the inhibition of hormone secretion, cell growth and invasion. Drug resistance occurs in a subset of patients and can involve different steps at different stages, such as following receptor activation by the agonist or during the final biological responses. Although the expression of somatostatin and dopamine receptors in cancer cells is a prerequisite for these drugs to reach a biological effect, their presence does not guarantee the success of the therapy. Successful therapy also requires the proper functioning of the machinery of signal transduction and the finely tuned regulation of receptor desensitization, internalization and intracellular trafficking. The present Review provides an updated overview of the molecular factors underlying the pharmacological resistance of pituitary tumours. The Review discusses the experimental evidence that supports a role for receptors and intracellular proteins in the function of SSTs and DRD2 and their clinical importance.

Pituitary disease and pregnancy

Pregnancy results in a significant change in both pituitary gland size and function. Due to this physiological adaptation, the diagnosis and management of pituitary diseases during pregnancy represents a particularly complex challenge. The presence of a functioning pituitary adenoma may be harmful to the health of the mother and fetus, and scientific evidence regarding the safety of drugs normally used to control hormone excess during pregnancy is scarce. In addition, pregnancy may be associated with the risk of the growth of a pre-existing pituitary adenoma. This review focuses on the diagnostic challenges in pregnant women with adenomas secreting prolactin, growth hormone, or adrenocorticotropic hormone. Some evidence-based recommendations for the treatment of these conditions during pregnancy are provided, and algorithms that could help monitor a pituitary adenoma during pregnancy are examined. Mention is also made of how hormone replacement therapy can be optimised in pregnant women with hypopituitarism. Finally, differential diagnosis between Sheehan's syndrome and lymphocytic hypophysitis, two pituitary disorders that may occur during pregnancy or delivery, is discussed.

Nomogram predictive model of post-operative recurrence in non-functioning pituitary adenoma

Background

To analyze and predict the possibility of post-operative recurrence in non-functioning pituitary adenoma (NFPA) patients, we investigated the clinical factors leading to tumor recurrence and built a nomogram predictive model based on these risk factors.

Methods

A single-center retrospective study was performed. A total of 145 NFPA patients who underwent surgical treatment at Shenzhen People's Hospital from September 2013 to January 2019 were selected. Among them, 52 patients were diagnosed with recurrence of NFPA according to follow-up investigations. Binary logistic regression analysis was used to determine the significant risk factors. A nomogram model was then built to predict recurrence using these factors.

Results

The univariate analysis and the binary logistic regression analysis showed that age, tumor size, cavernous invasion, sphenoid sinus invasion, and surgical extension were significant factors affecting tumor recurrence. We then built a nomogram model to predict post-operative recurrence in NFPA patients using these factors. The correlation analysis indicated that sphenoid sinus invasion [hazard ratio (HR) =13.14, 95% confidence interval (CI): 7.03-24.58, P<0.0001], cavernous sinus invasion (HR =7.53, 95% CI: 4.27-13.28, P<0.0001), and tumor size (HR =11.06, 95% CI: 6.11-20.03, P<0.0001) could promote the recurrence of NFPA. In contrast, advanced age (HR =0.50, 95% CI: 0.28-0.86, P<0.0001) and gross total resection (HR =0.12, 95% CI: 0.07-0.22, P<0.0001) could effectively inhibit recurrence.

Conclusions

In this study, we developed a nomogram predictive model based on the significant recurrence-associated factors for NFPA. This nomogram may aid neurosurgeons in the post-operative prediction of recurrence, and may facilitate tailored counseling of individual patients.

Therapeutic approach to non-functioning pituitary adenomas

The treatment of non-functioning pituitary adenomas raises two questions: when should they be treated and what role does each available treatment play. We review the usefulness of the different treatments and propose a therapeutic scheme based on the existing literature. Active treatment of pituitary adenomas should be performed when they produce symptoms, have contact with the optic tract, or have grown on imaging tests. The treatment is surgical, using radiotherapy for cases with significant non-removable postsurgical tumour remnants and for those in which histopathology studies show aggressive features. Medical treatment is reserved for situations in which surgical and radiotherapy treatments have been exhausted. The most advisable surgical treatment is endoscopic, although experienced neurosurgeons achieve results with microsurgery that are only slightly inferior.

Pituitary disease and pregnancy

Pregnancy results in a significant change in both pituitary gland size and function. Due to this physiological adaptation, the diagnosis and management of pituitary diseases during pregnancy represents a particularly complex challenge. The presence of a functioning pituitary adenoma may be harmful to the health of the mother and fetus, and scientific evidence regarding the safety of drugs normally used to control hormone excess during pregnancy is scarce. In addition, pregnancy may be associated with the risk of the growth of a pre-existing pituitary adenoma. This review focuses on the diagnostic challenges in pregnant women with adenomas secreting prolactin, growth hormone, or adrenocorticotropic hormone. Some evidence-based recommendations for the treatment of these conditions during pregnancy are provided, and algorithms that could help monitor a pituitary adenoma during pregnancy are examined. Mention is also made of how hormone replacement therapy can be optimised in pregnant women with hypopituitarism. Finally, differential diagnosis between Sheehan's syndrome and lymphocytic hypophysitis, two pituitary disorders that may occur during pregnancy or delivery, is discussed.

Beta-Arrestin 2 Is Required for Dopamine Receptor Type 2 Inhibitory Effects on AKT Phosphorylation and Cell Proliferation in Pituitary Tumors

Dopamine receptor type 2 (DRD2) agonists are the first-choice treatment for prolactin-secreting pituitary tumors but are poorly effective in nonfunctioning pituitary neuroendocrine tumors (NF-PitNETs). DRD2 reduces AKT phosphorylation in lactotrophs, but no data are available in NF-PitNETs. DRD2 effects on AKT are mediated by a β-arrestin 2-dependent mechanism in mouse striatum. The aim of this study was to investigate DRD2 effects on AKT phosphorylation and cell proliferation in human primary cultured NF-PitNET cells and in rat tumoral lactotroph cells MMQ, and to test β-arrestin 2 involvement. We found that the DRD2 agonist BIM53097 induced a reduction of the p-AKT/total-AKT ratio in MMQ (-32.8 ± 17.6%, p < 0.001 vs. basal) and in a subset (n = 15/41, 36.6%) of NF-PitNETs (subgroup 1). In the remaining NF-PitNETs (subgroup 2), BIM53097 induced an increase in p-AKT. The ability of BIM53097 to reduce p-AKT correlated with its antimitotic effect, since the majority of subgroup 1 NF-PitNETs was responsive to BIM53097, and nearly all subgroup 2 NF-PitNETs were resistant. β-Arrestin 2 was expressed in MMQ and in 80% of subgroup 1 NF-PitNETs, whereas it was undetectable in 77% of subgroup 2 NF-PitNETs. In MMQ, β-arrestin 2 silencing prevented DRD2 inhibitory effects on p-AKT and cell proliferation. Accordingly, β-arrestin 2 transfection in subgroup 2 NF-PitNETs conferred to BIM53097 the ability to inhibit both p-AKT and cell growth. In conclusion, we demonstrated that β-arrestin 2 is required for DRD2 inhibitory effects on AKT phosphorylation and cell proliferation in MMQ and NF-PitNETs, paving the way for a potential role of β-arrestin 2 as a biomarker predicting NF-PitNETs' responsiveness to treatment with dopamine agonists.

Resistance to Dopamine Agonists in Pituitary Tumors: Molecular Mechanisms

Pituitary neuroendocrine tumors (PitNET) are commonly benign tumors accounting for 10-25% of intracranial tumors. Prolactin-secreting adenomas represent the most predominant type of all PitNET and for this subtype of tumors, the medical therapy relies on the use of dopamine agonists (DAs). DAs yield an excellent therapeutic response in reducing tumor size and hormonal secretion targeting the dopamine receptor type 2 (D2DR) whose higher expression in prolactin-secreting adenomas compared to other PitNET is now well established. Moreover, although DAs therapy does not represent the first-line therapy for other PitNET, off-label use of DAs is considered in PitNET expressing D2DR. Nevertheless, DAs primary or secondary resistance, occurring in a subset of patients, may involve several molecular mechanisms, presently not fully elucidated. Dopamine receptors (DRs) expression is a prerequisite for a proper DA function in PitNET and several molecular events may negatively modify DR membrane expression, through the DRs down-regulation and intracellular trafficking, and DR signal transduction pathway. The current mini-review will summarise the presently known molecular events that underpin the unsuccessful therapy with DAs.

Multimodal Non-Surgical Treatments of Aggressive Pituitary Tumors

Up to 35% of aggressive pituitary tumors recur and significantly affect mortality and quality of life. Management can be challenging and often requires multimodal treatment. Current treatment options, including surgery, conventional medical therapies such as dopamine agonists, somatostatin receptor agonists and radiotherapy, often fail to inhibit pituitary tumor growth. Recently, anti-tumor effects of chemotherapeutic drugs such as Temozolomide, Capecitabine, and Everolimus, as well as peptide receptor radionuclide therapy on aggressive pituitary tumors have been increasingly investigated and yield mixed, although sometimes promising, outcomes. The purpose of this review is to provide thorough information on non-surgical medical therapies and their efficacies and used protocols for aggressive pituitary adenomas from pre-clinical level to clinical use.

Treatment Options for Gonadotroph Tumors: Current State and Perspectives

CONTEXT

Gonadotroph tumors represent approximatively one-third of anterior pituitary tumors, but despite their frequency, no medical treatment is currently recommended for them. This would be greatly needed because following surgery, which is the first-line treatment, a significant percentage of gonadotroph tumors regrow.

EVIDENCE ACQUISITION

We performed PubMed searches in March 2020 using the term "gonadotroph" in combination with 36 different keywords related to dopamine type 2 receptor agonists, somatostatin receptor (SST) ligands, temozolomide, peptide receptor radionuclide therapy (PRRT), immunotherapy, vascular endothelial growth factor receptor (VEGFR)-targeted therapy, mammalian target of rapamycin (mTOR) inhibitors, and tyrosine kinase inhibitors. Articles resulting from these searches, as well as relevant references cited by these articles were reviewed.

EVIDENCE SYNTHESIS

SST2 analogs have demonstrated only very limited antitumor effect, while high-dose cabergoline has been more effective in preventing tumor regrowth, but still in only a minority of cases. In the setting of an aggressive gonadotroph tumor, temozolomide is the recommended medical treatment, but has demonstrated also only limited efficacy. Still, its efficacy has been so far better than that of PRRT. No case of a gonadotroph tumor treated with pasireotide, VEGFR-targeted therapy, mTOR inhibitors, tyrosine kinase inhibitors, or immune checkpoint inhibitors is reported in literature.

CONCLUSIONS

Gonadotroph tumors need better phenotyping in terms of both tumor cells and associated tumor microenvironment to improve their treatment. Until formal recommendations will be available, we provide the readers with our suggested approach for the management of gonadotroph tumors, management that should be discussed within multidisciplinary teams.

Quantitative Analysis of Somatostatin and Dopamine Receptors Gene Expression Levels in Non-functioning Pituitary Tumors and Association with Clinical and Molecular Aggressiveness Features

The primary treatment for non-functioning pituitary tumors (NFPTs) is surgery, but it is often unsuccessful. Previous studies have reported that NFPTs express receptors for somatostatin (SST_1-5) and dopamine (DRDs) providing a rationale for the use of dopamine agonists and somatostatin analogues. Here, we systematically assessed SST_1-5 and DRDs expression by real-time quantitative PCR (RT-qPCR) in a large group of patients with NFPTs (n = 113) and analyzed their potential association with clinical and molecular aggressiveness features. SST_1-5 expression was also evaluated by immunohistochemistry. SST₃ was the predominant SST subtype detected, followed by SST₂, SST₅, and SST₁. DRD2 was the dominant DRD subtype, followed by DRD4, DRD5, and DRD1. A substantial proportion of NFPTs displayed marked expression of SST₂ and SST₅. No major association between SST_s and DRDs expression and clinical and molecular aggressiveness features was observed in NFPTs.

Accurate assessment of estrogen receptor profiles in non-functioning pituitary adenomas using RT-digital PCR and immunohistochemistry

BACKGROUND

Non-functioning pituitary adenomas (NFPAs) are common pituitary tumors, and surgery is generally the only treatment option. Few attempts have been made to explore target molecules for the development of NFPA pharmacological treatments.

METHOD

We quantitatively assessed the expression profiles of estrogen receptor (ER) transcripts and proteins in NFPA samples, using reverse transcription-digital polymerase chain reaction (RT-dPCR) and immunohistochemistry, and further investigated the correlations between the expression levels of ER and those of downstream responsive genes. All patients had undergone surgery at the same high-volume hospital. A total of 20 patients with NFPAs were included. All patients were new-onset, and none were diagnosed with intratumoral hemorrhages or cysts.

RESULTS

NFPA samples exhibited a bimodal ESR1 expression pattern and were categorized into significantly different high- and low-ESR1 expression level groups (P < 0.05). In contrast, expression levels of ESR1 variants and ESR2 could barely be detected. Similar results were obtained through the immunohistochemical staining of NFPAs, using well-validated antibodies against ERs. The expression levels of ESR1 positively correlated with those of GREB1, an estrogen-responsive gene [correlation coefficient (r) = 0.623, P = 0.003].

CONCLUSIONS

ESR1 expression levels in NFPAs exhibited a bimodal pattern and were positively correlated with GREB1 expression levels. The accurate assessment of ER expression levels may further advance future NFPA-related research.

Autophagy and Pituitary Adenoma

Pituitary adenomas (PAs) are common, benign intracranial tumors that are usually effectively controlled with surgery, pharmacotherapy or radiotherapy. Some PAs against which conventional treatment is ineffective are great clinical challenges at present. Autophagy is a widespread physiological process in cells. Through autophagy, cells can degrade damaged or redundant proteins and organelles and achieve the recycling of intracellular substances to maintain the homeostasis of the intracellular environment. An increasing number of studies have demonstrated the importance of autophagy in tumor therapy. Both radiotherapy and chemotherapy can induce autophagy, which plays different roles in the course of therapy. In recent years, there has been growing interest in the role of autophagy during the treatment of PAs. This chapter reviews the recent progress of research on autophagy in PA and the autophagic mechanisms in the treatment of PA.

The Role of Dopamine Agonists in Pituitary Adenomas

Dopamine agonist therapy is the primary therapy for prolactin-secreting adenomas and usually results in normoprolactinemia, eugonadism, and tumor reduction. Cabergoline is superior to bromocriptine with regard to efficacy and tolerance. Withdrawal of cabergoline can be attempted in patients with normal prolactin levels on low doses of medication and evidence of radiographic tumor involution. Dopamine agonists have been used off label in patients with acromegaly, Cushing disease, and nonfunctioning adenomas. A trial of cabergoline monotherapy can be effective in patients with biochemically mild acromegaly. Cabergoline combination with somatostatin receptor ligands or pegvisomant improves insulin-like growth factor level 1 in majority of patients.

TBR-760, a Dopamine-Somatostatin Compound, Arrests Growth of Aggressive Nonfunctioning Pituitary Adenomas in Mice

TBR-760 (formerly BIM-23A760) is a chimeric dopamine (DA)-somatostatin (SST) compound with potent agonist activity at both DA type 2 (D2R) and SST type 2 (SSTR2) receptors. Studies have shown that chimeric DA-SST compounds are more efficacious than individual DA and/or SST analogues, either alone or combined, in inhibiting secretion from primary cultures of human somatotroph and lactotroph tumor cells. Nonfunctioning pituitary adenomas (NFPAs) express both D2R and SSTR2 and, consequently, may respond to TBR-760. We used a mouse model with the pro-opiomelanocortin (POMC) gene knocked out that spontaneously develops aggressive NFPAs. Genomic microarray and DA and SST receptor messenger RNA expression analysis indicate that POMC KO mouse tumors and human NFPAs have similar expression profiles, despite arising from different cell lineages, establishing POMC KO mice as a model for study of NFPAs. Treatment with TBR-760 for 8 weeks resulted in nearly complete inhibition of established tumor growth, whereas tumors from vehicle-treated mice increased in size by 890 ± 0.7%. Comparing TBR-760 with its individual DA and SST components, TBR-760 arrested tumor growth. Treatment with equimolar or 10×-higher doses of the individual SST or DA agonists, either alone or in combination, had no significant effect. One exception was the lower dose of DA agonist that induced modest suppression of tumor growth. Only the chimeric compound TBR-760 arrested tumor growth in this mouse model of NFPA. Further, significant tumor shrinkage was observed in 20% of the mice treated with TBR-760. These results support the development of TBR-760 as a therapy for patients with NFPA.

Contemporary Management of Clinically Non-functioning Pituitary Adenomas: A Clinical Review

Non-functioning pituitary adenomas (NFPAs) are benign pituitary tumours that constitute about one-third of all pituitary adenomas. They typically present with symptoms of mass effects resulting in hypopituitarism, visual symptoms, or headache. Most NFPAs are macroadenomas (>1 cm in diameter) at diagnosis that can occasionally grow quite large and invade the cavernous sinus causing acute nerve compression and some patients may develop acute haemorrhage due to pituitary apoplexy. The progression from benign to malignant pituitary tumours is not fully understood; however, genetic and epigenetic abnormalities may be involved. Non-functioning pituitary carcinoma is extremely rare accounting for only 0.1% to 0.5 % of all pituitary tumours and presents with cerebrospinal, meningeal, or distant metastasis along with the absence of features of hormonal hypersecretion. Pituitary surgery through trans-sphenoidal approach has been the treatment of choice for symptomatic NFPAs; however, total resection of large macroadenomas is not always possible. Recurrence of tumours is frequent and occurs in 51.5% during 10 years of follow-up and negatively affects the overall prognosis. Adjuvant radiotherapy can decrease and prevent tumour growth but at the cost of significant side effects. The presence of somatostatin receptor types 2 and 3 (SSTR3 and SSTR2) and D2-specific dopaminergic receptors (D2R) within NFPAs has opened a new perspective of medical treatment for such tumours. The effect of dopamine agonist from pooled results on patients with NFPAs has emerged as a very promising treatment modality as it has resulted in reduction of tumour size in 30% of patients and stabilization of the disease in about 58%. Despite the lack of long-term studies on the mortality, the available limited evidence indicates that patients with NFPA have higher standardized mortality ratios (SMR) than the general population, with women particularly having higher SMR than men. Older age at diagnosis and higher doses of glucocorticoid replacement therapy are the only known predictors for increased mortality.

Folate Receptor Near-Infrared Optical Imaging Provides Sensitive and Specific Intraoperative Visualization of Nonfunctional Pituitary Adenomas

BACKGROUND

Surgical resection is the primary treatment for nonfunctional (NF) pituitary adenomas, but gross-total resection is difficult to achieve in all cases. NF adenomas overexpress folate receptor alpha (FRα).

OBJECTIVE

To test the hypothesis that we could target FRα for highly sensitive and specific intraoperative detection of NF adenomas using near-infrared (NIR) imaging.

METHODS

Fourteen patients with NF pituitary adenoma were infused with the folate analog NIR dye OTL38 preoperatively. NIR fluorescence signal-to-background ratio (SBR) was recorded for each tumor during resection of the adenomas. Extent of surgery was not modified based on the presence or absence of fluorescence. Immunohistochemistry was performed to assess FRα expression in all specimens. Magnetic resonance imaging (MRI) was performed postoperatively to assess residual neoplasm.

RESULTS

Nine adenomas overexpressed FRα and fluoresced with a NIR SBR of 3.2 ± 0.52, whereas the 5 non-FRα-overexpressing adenomas fluoresced with an SBR of 1.5 ± 0.21. Linear regression demonstrated a significant correlation between intraoperative SBR and the FRα expression (P-value < .001). Analysis of 14 margin samples revealed that the surgeon's impression of the tissue had 83% sensitivity, 100% specificity, 100% positive predictive value, and 89% negative predictive value, while NIR fluorescence had 100% for all values. NIR fluorescence accurately predicted postoperative MRI results in 78% of FRα-overexpressing patients.

CONCLUSION

Preoperative injection of folate-tagged NIR dye provides strong signal and visualization of NF pituitary adenomas. It is 100% sensitive and specific for detecting margin neoplasm and can predict postoperative MRI findings. Our results suggest that NIR fluorescence may be superior to white-light visualization alone and may improve resection rates in NF pituitary adenomas.

Gonadotroph Tumors Show Subtype Differences That Might Have Implications for Therapy

Gonadotroph tumors, although frequent, are poorly studied and understood, being usually included in the larger nonfunctioning pituitary neuroendocrine tumors (PitNETs) group. Moreover, in comparison to the other types of PitNETs, no established medical treatment is currently available for gonadotroph tumors. Here, we performed a retrospective study and analyzed the clinicopathological characteristics of 98 gonadotroph tumors operated in a single large pituitary center. Although being larger in men (p = 0.01), the aggressiveness of gonadotroph tumors did not appear to be sex-related. LH tumors were rare (4/98) and exclusively encountered in men. Somatostatin receptor type 5 (SST5) was absent in all analyzed tumors. The immunoreactive score (IRS) of somatostatin receptor type 2 (SST2) and of estrogen receptor alpha (ERα) was associated with the histological subtype (p = 0.01 and p = 0.02). IRS ERα correlated moderately with IRS SST2 in all (rho = 0.44, adjusted p-value = 0.0001) and in male (rho = 0.51, adjusted p-value = 0.0002) patients, and with follicle-stimulating hormone (FSH) percentage in all (rho = 0.40, adjusted p-value = 0.0005) and in female (rho = 0.58, adjusted p-value = 0.004) patients. In conclusion, gonadotroph tumors exhibit histological characteristics pinpointing the existence of several subtypes. Their heterogeneity warrants further investigations and may have to be taken into account when studying these tumors and investigating treatment options.

Current perspectives on recurrent pituitary adenoma: The role and timing of surgery vs adjuvant treatment

The clinical course of pituitary adenoma can be highly variable. Aggressive pituitary tumours may require multimodal therapy with multiple operations. Even standard pituitary adenomas exhibit relatively high long-term recurrence rates and delayed intervention is often required. The indications for revision surgery in the endoscopic era are expanding for both functioning and nonfunctioning tumours, including access to the cavernous sinus and intracranial compartments. Although revision surgery can be challenging, it has been demonstrated to be both safe and effective. The question of the use of early radiotherapy in pituitary adenoma remains controversial. Our increasing understanding of pituitary tumour biology facilitates individualized treatment and surveillance protocols, with early intervention in high-risk adenoma subtypes. In this review, we discuss the treatment options for recurring pituitary tumours and focus on the role of revision surgery.

Treatment of Pituitary and Other Tumours with Cabergoline: New Mechanisms and Potential Broader Applications

Cabergoline is a dopamine agonist that has been used as the first-line treatment option for prolactin-secreting pituitary adenomas for several decades. It not only suppresses hormone production from these prolactinomas, but also causes tumour shrinkage. Recent studies revealed some novel mechanisms by which cabergoline suppresses tumour cell proliferation and induces cell death. In this article, we review the most recent findings in cabergoline studies, focusing on its anti-tumour function. These studies suggest the potential broader clinical use of cabergoline in the treatment of other tumours such as breast cancer, pancreatic neuroendocrine tumours, and lung cancer.

Hyperprolactinaemia

Hyperprolactinaemia is one of the most common problems in clinical endocrinology. It relates with various aetiologies (physiological, pharmacological, pathological), the clarification of which requires careful history taking and clinical assessment. Analytical issues (presence of macroprolactin or of the hook effect) need to be taken into account when interpreting the prolactin values. Medications and sellar/parasellar masses (prolactin secreting or acting through “stalk effect”) are the most common causes of pathological hyperprolactinaemia. Hypogonadism and galactorrhoea are well-recognized manifestations of prolactin excess, although its implications on bone health, metabolism and immune system are also expanding. Treatment mainly aims at restoration and maintenance of normal gonadal function/fertility, and prevention of osteoporosis; further specific management strategies depend on the underlying cause. In this review, we provide an update on the diagnostic and management approaches for the patient with hyperprolactinaemia and on the current data looking at the impact of high prolactin on metabolism, cardiovascular and immune systems.

Intraoperative near-infrared imaging with receptor-specific versus passive delivery of fluorescent agents in pituitary adenomas

OBJECTIVE

Intraoperative molecular imaging with tumor-targeted fluorescent dyes can enhance resection rates. In contrast to visible-light fluorophores (e.g., 5-aminolevulinic-acid), near-infrared (NIR) fluorophores have increased photon tissue penetration and less contamination from tissue autofluorescence. The second-window ICG (SWIG) technique relies on passive accumulation of indocyanine green (ICG) in neoplastic tissues. OTL38, conversely, targets folate receptor overexpression in nonfunctioning pituitary adenomas. In this study, we compare the properties of these 2 modalities for NIR imaging of pituitary adenomas to better understand the potential for NIR imaging in neurosurgery.

METHODS

A total of 39 patients with pituitary adenomas were enrolled between June 2015 and January 2018 in 2, sequential, IRB-approved studies. Sixteen patients received systemic ICG infusions 24 hours prior to surgery, and another 23 patients received OTL38 infusions 2-3 hours prior to surgery. NIR fluorescence signal-to-background ratio (SBR) was recorded during and after resection. Immunohistochemistry was performed on the 23 adenomas resected from patients who received OTL38 to assess expression of folate receptor-alpha (FRα).

RESULTS

All 16 adenomas operated on after ICG administration demonstrated strong NIR fluorescence (mean SBR 4.1 ± 0.69 [SD]). There was no statistically significant difference between the 9 functioning and 7 nonfunctioning adenomas (p = 0.9). After administration of OTL38, the mean SBR was 1.7 ± 0.47 for functioning adenomas, 2.6 ± 0.91 for all nonfunctioning adenomas, and 3.2 ± 0.53 for the subset of FRα-overexpressing adenomas. Tissue identification with white light alone for all adenomas demonstrated 88% sensitivity and 90% specificity. SWIG demonstrated 100% sensitivity but only 29% specificity for both functioning and nonfunctioning adenomas. OTL38 was 75% sensitive and 100% specific for all nonfunctioning adenomas, but when assessment was limited to the 9 FRα-overexpressing adenomas, the sensitivity and specificity of OTL38 were both 100%.

CONCLUSIONS

Intraoperative imaging with NIR fluorophores demonstrates highly sensitive detection of pituitary adenomas. OTL38, a folate-receptor-targeted fluorophore, is highly specific for nonfunctioning adenomas but has no utility in functioning adenomas. SWIG, which relies on passive diffusion into neoplastic tissue, is applicable to both functioning and nonfunctioning pituitary adenomas, but it is less specific than targeted fluorophores. Thus, targeted and nontargeted NIR fluorophores play important, yet distinct, roles in intraoperative imaging. Selectively and intelligently using either agent has the potential to greatly improve resection rates and outcomes for patients with intracranial tumors.