Advances in understanding pituitary tumors

The nomogram for predicting nasal bleeding after endoscopic transsphenoidal resection of pituitary adenomas: a retrospective study

Objective

This study aimed to develop and validate a dynamic nomogram to assess the risk of nasal bleeding after endoscopic transnasal transsphenoidal pituitary tumor resection.

Methods

A retrospective analysis was conducted on patients who underwent endoscopic transnasal transsphenoidal pituitary tumor resection from June 2019 to June 2021. Univariate and multivariate logistic regression analyses were used to screen for independent risk factors for nasal bleeding from the training set. A multivariate logistic regression model was established, a nomogram was plotted, and it was validated in an internal validation set. The performance of the nomogram was evaluated based on the receiver operating characteristic (ROC) curve, calibration curve, and decision curve analysis (DCA).

Results

The nomogram indicators included anticoagulant use, sphenoid sinus artery injury, nasal irrigation, platelet count (PLT), and constipation. The predictive model had an area under the ROC curve of 0.932 (95% CI: 0.873-0.990) and 0.969 (95% CI: 0.940-0.997) for the training and validation sets, respectively, indicating good discrimination. The calibration curve showed good consistency between the actual and predicted incidence of nasal bleeding (p > 0.05). DCA indicated that the nomogram had good clinical net benefit in predicting postoperative nasal bleeding in patients.

Conclusion

In summary, this study explored the incidence and influencing factors of nasal bleeding after endoscopic transnasal transsphenoidal pituitary tumor resection and established a predictive model to assist clinical decision-making.

Successful medical management of a pituitary macroadenoma with features of resistant acromegaly and hyperprolactinemia using pasireotide

BACKGROUND

The somatostatin analog, pasireotide, is used for the treatment of acromegaly after the failure of surgery and/or first-line medical treatment.

CASE PRESENTATION

A 48-year-old male reported that during a workup for obesity in his home country, hyperprolactinemia was diagnosed and a 3.5 × 3.5 cm pituitary macroadenoma was identified on pituitary MRI. He received cabergoline for 6 months; then he was lost to follow-up. He presented at our Endocrine clinic 2 years later for treatment of obesity (BMI 49.5 kg/m2). Biochemical workup revealed that in addition to hyperprolactinemia (7,237 [normal: 85-323 mIU/L), he had acromegaly, evident by elevated insulin-like growth factor 1 (IGF-1) level (450 [normal: 88-210 µg/L]), and a positive growth hormone suppression test, secondary hypothyroidism, and secondary hypogonadism. Pituitary MRI showed that the adenoma encased parts of the left and right internal carotid arteries and encroached on the optic chiasm. Surgical excision was therefore not feasible. He was treated with cabergoline and later, long-acting release (LAR) octreotide. Prolactin levels were reduced with cabergoline, but IGF-1 levels did not respond to octreotide, and it was discontinued. The patient abandoned radiotherapy after two sessions. He was started on LAR pasireotide 40 mg every 4 weeks and continued on cabergoline 0.5 mg per week. His biochemical response was dramatic, with a near normalization of IGF-1 levels in 3 months. After 6 months from starting pasireotide, we increased cabergoline dose from 0.5 mg/week to 3 mg/week. Three months later, IGF-1 level was normalized. The patient developed type 2 diabetes as a side effect of pasireotide; however, this was well-controlled with medications.

CONCLUSIONS

The case suggests that pasireotide can provide marked biochemical improvement in acromegaly after the failure of both cabergoline monotherapy and cabergoline plus octreotide. This further confirms a potentially efficacious treatment regimen in treatment-resistant acromegaly with hyperprolactinemia.

Localization of TSH-secreting pituitary adenoma using 11C-methionine image subtraction

BACKGROUND

Pituitary adenomas (PA) affect ~ 1:1200 of the population and can cause a wide range of symptoms due to hormone over-secretion, loss of normal pituitary gland function and/or compression of visual pathways, resulting in significantly impaired quality of life. Surgery is potentially curative if the location of the adenoma can be determined. However, standard structural (anatomical) imaging, in the form of MRI, is unable to locate all tumors, especially microadenomas (< 1 cm diameter). In such cases, functional imaging [¹¹C-methionine PET/CT (Met-PET)] can facilitate tumor detection, although may be inconclusive when the adenoma is less metabolically active. We, therefore, explored whether subtraction imaging, comparing findings between two Met-PET scans with medical therapy-induced suppression of tumor activity in the intervening period, could increase confidence in adenoma localization. In addition, we assessed whether normalization to a reference region improved consistency of pituitary gland signal in healthy volunteers who underwent two Met-PET scans without medical suppression.

RESULTS

We found that the mean percentage differences in maximum pituitary uptake between two Met-PET scans in healthy volunteers were 2.4% for (SUVr) [cerebellum], 8.8% for SUVr [pons], 5.2% for SUVr [gray matter] and 23.1% for the SUVbw [no region]. Laterality, as measured by contrast-noise ratio (CNR), indicated the correct location of the adenoma in all three image types with mean CNR values of 6.2, 8.1 and 11.1 for SUVbw, SUVbwSub and SUVrSub [cerebellum], respectively. Subtraction imaging improved CNR in 60% and 100% of patients when using images generated from SUVbw [no region] and SUVr [cerebellum] scans compared to standard clinical SUVbw imaging.

CONCLUSIONS

Met-PET scans should be normalized to the cerebellum to minimize the effects of physiological variation in pituitary gland uptake of 11C-methionine, especially when comparing serial imaging. Subtraction imaging following endocrine suppression of tumor function improved lateralization of PA when compared with single time point clinical Met-PET but, importantly, only if the images were normalized to the cerebellum prior to subtraction.

Tamoxifen Exerts Anticancer Effects on Pituitary Adenoma Progression via Inducing Cell Apoptosis and Inhibiting Cell Migration

Although pituitary adenomas are histologically benign, they are often accompanied by multiple complications, such as cardiovascular disease and metabolic dysfunction. In the present study, we repositioned the Food and Drug Administration -approved immune regulator tamoxifen to target STAT6 based on the genomics analysis of PAs. Tamoxifen inhibited the proliferation of GH3 and AtT-20 cells with respective IC₅₀ values of 9.15 and 7.52 μM and increased their apoptotic rates in a dose-dependent manner. At the molecular level, tamoxifen downregulated phosphorylated PI3K, phosphorylated AKT and the anti-apoptotic protein Bcl-2 and increased the expression of pro-apoptotic proteins p53 and Bax in GH3 and AtT-20 cells. Furthermore, tamoxifen also inhibited the migration of both cell lines by reprogramming tumor-associated macrophages to the M1 phenotype through STAT6 inactivation and inhibition of the macrophage-specific immune checkpoint SHP1/SHP. Finally, administration of tamoxifen (20, 50, 100 mg·kg⁻¹·d⁻¹, for 21 days) inhibited the growth of pituitary adenomas xenografts in nude mice in a dose-dependent manner. Taken together, tamoxifen is likely to be a promising combination therapy for pituitary adenomas and should be investigated further.

Gender-Specific Efficacy Revealed by Head-to-Head Comparison of Pasireotide and Octreotide in a Representative In Vivo Model of Nonfunctioning Pituitary Tumors

Simple Summary

No effective medical therapy exists for residual/recurrent nonfunctioning pituitary tumors (NFPTs). First-generation somatostatin analogs (SSAs) like octreotide targeting somatostatin receptor type 2 (SSTR2) are the mainstay therapy for functioning PTs, but have shown little effect in NFPTs. This is in agreement with an SSTR profile characterized by low SSTR2, and high SSTR3 levels in the latter. Pasireotide a multi-SSTR-preferring SSA, should be effective against NFPTs. To test this hypothesis, we conducted a head-to-head comparison of octreotide and pasireotide in the only spontaneous in vivo model of NFPTs (MENX rats), which recapitulates the human disease. Pasireotide showed a superior anti-tumor effect vs. octreotide, especially in females. Interestingly, Sstr3 levels were higher in female vs. male NFPTs. A sex-related SSTR3 expression may extend to human NFPTs, thereby representing a tool for patient stratification. Our results have translational relevance for the medical treatment of patients with residual/recurrent NFPTs currently lacking efficacious therapeutic options.

Abstract

Invasive nonfunctioning pituitary tumors (NFPTs) are non-resectable neoplasms associated with frequent relapse and significant comorbidities. Current treatments, including somatostatin receptor 2 (SSTR2)-directed somatostatin analogs (SSAs), often fail against NFPTs. Thus, identifying effective therapies is clinically relevant. As NFPTs express SSTR3 at high levels, pasireotide, a multireceptor-targeted SSA, might be beneficial. Here we evaluated pasireotide in the only representative model of spontaneous NFPTs (MENX rats) in vivo. Octreotide long-acting release (LAR), pasireotide LAR, or placebo, were administered to age-matched, tumor-bearing MENX rats of both sexes for 28 d or 56 d. Longitudinal high-resolution magnetic resonance imaging monitored tumor growth. While tumors in placebo-treated rats increased in volume over time, PTs in drug-treated rats displayed significant growth suppression, and occasional tumor shrinkage. Pasireotide elicited stronger growth inhibition. Radiological responses correlated with tumors’ proliferation rates. Both SSAs, but especially pasireotide, were more effective in female vs. male rats. Basal Sstr3 expression was significantly higher in the former group. It is noteworthy that female human NFPTs patients also have a trend towards higher SSTR3 expression. Altogether, our studies provide the rationale for testing pasireotide in patients with residual/recurrent NFPTs. If confirmed, the sex-related SSTR3 expression might be used as criteria to stratify NFPTs patients for treatment with pasireotide.

A Somatostatin Receptor Subtype-3 (SST3) Peptide Agonist Shows Antitumor Effects in Experimental Models of Nonfunctioning Pituitary Tumors

PURPOSE

Somatostatin analogues (SSA) are efficacious and safe treatments for a variety of neuroendocrine tumors, especially pituitary neuroendocrine tumors (PitNET). Their therapeutic effects are mainly mediated by somatostatin receptors SST₂ and SST₅. Most SSAs, such as octreotide/lanreotide/pasireotide, are either nonselective or activate mainly SST₂. However, nonfunctioning pituitary tumors (NFPTs), the most common PitNET type, mainly express SST₃ and finding peptides that activate this particular somatostatin receptor has been very challenging. Therefore, the main objective of this study was to identify SST₃-agonists and characterize their effects on experimental NFPT models.

EXPERIMENTAL DESIGN

Binding to SSTs and cAMP level determinations were used to screen a peptide library and identify SST₃-agonists. Key functional parameters (cell viability/caspase activity/chromogranin-A secretion/mRNA expression/intracellular signaling pathways) were assessed on NFPT primary cell cultures in response to SST₃-agonists. Tumor growth was assessed in a preclinical PitNET mouse model treated with a SST₃-agonist.

RESULTS

We successfully identified the first SST₃-agonist peptides. SST₃-agonists lowered cell viability and chromogranin-A secretion, increased apoptosis in vitro, and reduced tumor growth in a preclinical PitNET model. As expected, inhibition of cell viability in response to SST₃-agonists defined two NFPT populations: responsive and unresponsive, wherein responsive NFPTs expressed more SST₃ than unresponsive NFPTs and exhibited a profound reduction of MAPK, PI3K-AKT/mTOR, and JAK/STAT signaling pathways upon SST₃-agonist treatments. Concurrently, SSTR3 silencing increased cell viability in a subset of NFPTs.

CONCLUSIONS

This study demonstrates that SST₃-agonists activate signaling mechanisms that reduce NFPT cell viability and inhibit pituitary tumor growth in experimental models that expresses SST₃, suggesting that targeting this receptor could be an efficacious treatment for NFPTs.

Emerging Role of USP8, HMGA, and Non-Coding RNAs in Pituitary Tumorigenesis

Two novel molecular mechanisms with a driver role in pituitary tumorigenesis have been recently identified. They are (a) mutations in the Ubiquitin-Specific Protease 8 (USP8) gene in corticotroph tumors and (b) overexpression of the HMGA1 and HMGA2 genes in most of the pituitary tumors. Moreover, deregulated expression of the non-coding RNAs has been very frequently observed in this neoplasia. The aim of this review is to better elucidate the role, the mechanisms, and the possible clinical impact of these novel alterations in the development of pituitary neoplasia.

Biguanides Exert Antitumoral Actions in Pituitary Tumor Cells Through AMPK-Dependent and -Independent Mechanisms

CONTEXT

Pituitary neuroendocrine tumors (PitNETs) are a commonly underestimated pathology in terms of incidence and associated morbimortality. Currently, an appreciable subset of patients are resistant or poorly responsive to the main current medical treatments [i.e., synthetic somatostatin analogs (SSAs) and dopamine agonists]. Thus, development and optimization of novel and available medical therapies is necessary. Biguanides (metformin, buformin, and phenformin) are antidiabetic drugs that exert antitumoral actions in several tumor types, but their pharmacological effects on PitNETs are poorly known.

OBJECTIVE

We aimed to explore the direct effects of biguanides on key functions (cell viability, hormone release, apoptosis, and signaling pathways) in primary cell cultures from human PitNETs and cell lines. Additionally, we evaluated the effect of combined metformin with SSAs on cell viability and hormone secretion.

DESIGN

A total of 13 corticotropinomas, 13 somatotropinomas, 13 nonfunctioning PitNETs, 3 prolactinomas, and 2 tumoral pituitary cell lines (AtT-20 and GH3) were used to evaluate the direct effects of biguanides on cell viability, hormone release, apoptosis, and signaling pathways.

RESULTS

Biguanides reduced cell viability in all PitNETs and cell lines (with phenformin being the most effective biguanide) and increased apoptosis in somatotropinomas. Moreover, buformin and phenformin, but not metformin, reduced hormone secretion in a cell type-specific manner. Combination metformin/SSA therapy did not increase SSA monotherapy effectiveness. Effects of biguanides on PitNETs could involve the modulation of AMP-activated protein kinase-dependent ([Ca2+]i, PI3K/Akt) and independent (MAPK) mechanisms.

CONCLUSION

Altogether, our data unveil clear antitumoral effects of biguanides on PitNET cells, opening avenues to explore their potential as drugs to treat these pathologies.

Risk factors and the prognosis of sexual dysfunction in male patients with pituitary adenomas: a multivariate analysis

The impact of sexual dysfunction (SD) is distressing to many male patients with pituitary adenomas which affect both physical and psychological health. The research explored to identify risk factors affecting sexual function and the prognosis of male patients with pituitary adenomas. Two hundred and fifty-four male patients, who aged between 18 and 60 (mean ± s.d.: 44.16 ± 10.14) years and diagnosed with pituitary adenomas, were retrospectively analyzed. One hundred and fifty-nine patients (62.6%) complained of SD prior to surgery. The mean International Index of Erectile Function (IIEF-5) in patients with giant adenomas was 16.13 ± 2.51, much smaller than those with microadenomas or macroadenomas (P < 0.05). All the patients showed significant improvement in terms of erectile dysfunction (ED) following surgery (P < 0.05). In addition, complete resection achieved a higher degree of SD relief than partial resection. The incidence of SD in functioning pituitary adenomas (FPAs) was much higher than that in nonfunctioning pituitary adenomas (NFPAs) (P < 0.05). In addition, compared with NFPAs, males with prolactinomas (82.8%) had the higher prevalence of SD and significantly improvement following surgical intervention (P < 0.05). An inverse relationship was identified between decreasing testosterone levels and increasing incidence of SD before surgery (P < 0.05). There was no significant difference between 6 months and 12 months after surgery in serum testosterone level (P > 0.05). Our results indicated that surgical therapy could be optimized for improvements in SD and that testosterone levels can be used as a sensitive indicator to predict the recovery rate of sexual function in patients with pituitary adenomas following surgery and the serum testosterone level will stay stable in 6 months after surgery.

Pharmacokinetic analysis for the differentiation of pituitary microadenoma subtypes through dynamic contrast-enhanced magnetic resonance imaging

The value of pharmacokinetic parameters derived from dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) in distinguishing pituitary microadenoma subtypes was investigated in the present study. Pathology and follow-up outcomes were applied as the gold standard for differentiating between 76 patients with pituitary microadenomas (38 prolactin-producing tumors, 17 adrenocorticotropic hormone adenomas and 21 growth hormone-producing tumors) and 20 patients with normal pituitary glands. DCE-MRI was conducted to obtain the following quantitative permeability parameters: Volume transfer constant (K^trans), rate constant (K_ep) and extracellular extravascular volume fraction (V_e). Among the 76 cases included, 61 were visually diagnosed using conventional MRI. The K^trans, K_ep and V_e of the microadenoma cases were 0.472±0.292/min, 0.765±0.359/min and 0.792±0.345, respectively. The K^trans, K_ep and V_e of the normal control group were 0.902±0.238/min, 1.208±0.599/min and 0.928±0.378, respectively. The K^trans and K_ep of patients with microadenomas were significantly lower compared with those of the normal controls (P<0.05). However, the V_e of the two groups did not significantly differ. Subtype differentiation analysis revealed that patients with growth hormone-producing tumors exhibited the highest K^trans value (P<0.05). K_ep significantly differed between growth hormone-producing tumors and the other two subtypes (P<0.05), but did not significantly differ among three subtypes. Receiver-operator characteristic analysis indicated that the area under the curve values of K^trans and K_ep were 0.884 and 0.728, respectively. Sensitivity and specificity were 95.0 and 82.6%, respectively, when K^trans was set to 0.614/min as the cut-off value, and when the K_ep cut-off value was set to 0.985/min, sensitivity and specificity were 60.0 and 81.3%, respectively. In conclusion, K^trans and K_ep derived from DCE-MRI could be applied to detect and identify microadenoma subtypes. K^trans better reflects the blood perfusion alterations exhibited by patients with different microadenoma subtypes.

Utilization of the Nasoseptal Flap for Repair of Cerebrospinal Fluid Leak after Endoscopic Endonasal Approach for Resection of Pituitary Tumors

Background

One of the most frequent complications after endoscopic endonasal approach (EEA) for resection of pituitary tumors is cerebrospinal fluid (CSF) leaks. With the introduction of the pedicled nasoseptal flap, the reconstruction of the skull base has improved significantly resulting in a decrease in the occurrence of persistent CSF leaks. We present our experience utilizing the pedicled nasoseptal flap technique after EEA for reconstruction of the skull base in cases where CSF leak was detected.

Methods

Data for patients undergoing EEA for pituitary tumors was retrospectively reviewed. These included demographic, clinical, operative, radiographic, and pathological information. Incidence of post-operative complications and CSF leaks were recorded. Descriptive statistical analysis was performed.

Results

Between 2008 and 2015, 67 patients and 69 hospital admissions with pituitary tumors underwent a nasoseptal flap to reconstruct a skull base defect at Johns Hopkins Hospital. The mean age at surgery was 54.5±14.2 years. Fifty-two percent of patients were male. Forty-six percent of patients were white, 33% African-American, and 12% belonged to other racial groups. There was an intraoperative CSF leak in 39% of patients. Seventy percent of patients with an intraoperative CSF leak had a nasoseptal flap reconstruction of the skull base. There were zero postoperative CSF leaks.

Conclusion

With the introduction of the pedicled nasoseptal flap for reconstruction of the skull base after EEA for resection of pituitary adenomas, the incidence of postoperative CSF leaks has decreased significantly. In this retrospective analysis, we demonstrate the effectiveness of the use of nasoseptal flap in repairing CSF leak after EEA.

Immunotherapy and potential molecular targets for the treatment of pituitary adenomas resistant to standard therapy: a critical review of potential therapeutic targets and current developments

INTRODUCTION

Pituitary adenomas (PAs) are primary central nervous system (CNS) tumors, accounting for as much as 25% of intracranial neoplasms. Although existing remedies show success in treating most PAs, treatment of invasive and non-functioning PAs, in addition to functioning PAs unresponsive to standard therapy, remains challenging. With the continually increasing understanding of biochemical pathways involved in tumorigenesis, immunotherapy stands as a promising alternative therapy for pituitary tumors that are resistant to standard therapy.

EVIDENCE ACQUISITION

A literature search was conducted of the PubMed database for immunotherapies of PAs. The search yielded a total of 2621 articles, 26 of which were included in our discussion.

EVIDENCE SYNTHESIS

Several pathologically expressed molecules could potentially serve as promising targets of current or future immunotherapies for PAs. Programmed death ligand-1, matrix metalloproteinases, EpCAM (Trop1) and Trop2, cancer-testis antigen MAGE-A3, epidermal growth factor receptor (EGFR), folate receptor alpha, vascular endothelial growth factor, and galectin-3 have all been implicated as crucial factors involved with tumor survival and invasion. Inhibition of these pathways may prove efficacious in the management of invasive and treatment-resistant PAs.

CONCLUSIONS

Rapid advancements in tumor immunology may increase the probability of successful treatment of PAs by exploitation of the normal immune response or by targeting novel proteins. Current research on many of the targets reviewed in this article are successfully being utilized to manage various neoplastic disease including CNS tumors. These therapies may eventually play a key role in the treatment of PAs that do not respond to standard therapy.

Notch system is differentially expressed and activated in pituitary adenomas of distinct histotype, tumor cell lines and normal pituitaries

Pituitary adenomas are among the most frequent intracranial neoplasms and treatment depends on tumor subtype and clinical features. Unfortunately, non responder cases occur, then new molecular targets are needed.

Notch system component expression and activation data are scarce in pituitary tumorigenesis, we therefore aimed to characterize Notch system in pituitary tumors of different histotype. In human pituitary adenomas we showed NOTCH1-4 receptors, JAGGED1 ligand and HES1 target gene expression with positive correlations between NOTCH1,2,4 and HES1, and NOTCH3 and JAGGED1 denoting Notch system activation in a subset of tumors. Importantly, NOTCH3 positive cells were higher in corticotropinomas and somatotropinomas compared to non functioning adenomas. In accordance, Notch activation was evidenced in AtT20 tumor corticotropes, with higher levels of NOTCH1-3 active domains, Jagged1 and Hes1 compared to normal pituitary.

In the prolactinoma cell lines GH3 and MMQ, in vivo GH3 tumors and normal glands, Notch system activation was lower than in corticotropes. In MMQ cells only the NOTCH2 active domain was increased, whereas NOTCH1 active domain was higher in GH3 tumors. High levels of Jagged1 and Dll1 were found solely in GH3 cells, and Hes1, Hey1 and Hey2 were expressed in a model dependent pattern.

Prolactinomas harbored by lacDrd2KO mice expressed high levels of NOTCH1 active domain and reduced Hes1.

We show a differential expression of Notch system components in tumoral and normal pituitaries and specific Notch system involvement depending on adenoma histotype, with higher activation in corticotropinomas. These data suggest that targeting Notch pathway may benefit non responder pituitary adenomas.

Programmed cell senescence: role of IL-6 in the pituitary

IL-6 is a pleiotropic cytokine with multiple pathophysiological functions. As a key factor of the senescence secretome, it can not only promote tumorigenesis and cell proliferation but also exert tumor suppressive functions, depending on the cellular context. IL-6, as do other cytokines, plays important roles in the function, growth and neuroendocrine responses of the anterior pituitary gland. The multiple actions of IL-6 on normal and adenomatous pituitary function, cell proliferation, angiogenesis and extracellular matrix remodeling indicate its importance in the regulation of the anterior pituitary. Pituitary tumors are mostly benign adenomas with low mitotic index and rarely became malignant. Premature senescence occurs in slow-growing benign tumors, like pituitary adenomas. The dual role of IL-6 in senescence and tumorigenesis is well represented in pituitary tumor development, as it has been demonstrated that effects of paracrine IL-6 may allow initial pituitary cell growth, whereas autocrine IL-6 in the same tumor triggers senescence and restrains aggressive growth and malignant transformation. IL-6 is instrumental in promotion and maintenance of the senescence program in pituitary adenomas.

A rare case of pituitary chromophobe carcinoma in a dog: clinical, tomographic and histopathological findings

A 9 year old male mixed-breed dog was presented for progressive aggressiveness towards the owner. The neurological evaluation was consistent with a forebrain syndrome. Magnetic Resonance Imaging (MRI) of the brain revealed enlargement of the third ventricle and presence of a large spheroidal neoplasm in the sellar/parasellar region suggestive of a pituitary macroadenoma. On the owner request, the dog was euthanized. Histopathological examination revealed the presence of a pituitary chromophobe carcinoma. To the author’s knowledge, pituitary carcinomas have been rarely described in dogs, especially the chromophobe subtype.

Three-Dimensional Endoscopic Endonasal Approach and Outcomes in Sellar Lesions: A Single-Center Experience of 104 Cases

BACKGROUND

Pituitary tumors account for approximately 15% of primary intracranial neoplasms and often are diagnosed incidentally. Common sellar lesions are pituitary adenomas, craniopharyngiomas, and Rathke cleft cysts. Currently endoscopic transsphenoidal approaches are largely used, and many centers also use 3-dimensional (3D) technology, although additional results of long-term follow-up are still being accumulated.

METHODS

We present a retrospective analysis of 104 patients with sellar lesions (57 male and 47 female, mean age 52 years) who underwent 3D endoscopic transsphenoidal surgery in our center from December 2011 to March 2015 and were followed up for a mean time of 18 months.

RESULTS

A total of 16 patients were diagnosed with growth hormone-secreting adenomas, 9 with adrenocorticotropic hormone-secreting, 5 with prolactin-secreting, and 2 with thyroid-stimulating hormone-secreting tumors and 58 with nonsecreting pituitary adenomas. Five patients had Rathke cleft cysts, 5 craniopharyngiomas, 2 fibrous solitary tumors, 1 a metastasis, and 1 a chordoma. At baseline, 47 patients (45.2%) had hormonal changes and 52 (50%) had visual field changes. Complete resection was achieved in 73 patients (70.1%). Follow-up evaluation detected hormonal remission in 7 patients with Cushing disease (77.7%) and in 11 patients with acromegaly (68.7%). Complications were cerebrospinal fluid leak in 5 cases (4.8%) and transient diabetes insipidus in 6 cases (5.7%). A total of 55 patients (52.9%) were discharged less than 72 hours after surgery.

CONCLUSIONS

The use of an endoscopic endonasal approach with 3D technology provides several advantages relating to patient length of stay, rate of complications, postoperative recovery, and novice surgeons' training. Advantages of 3D endoscopy and long-term follow-up still need further elucidation.

Temozolomide treatment of pituitary carcinomas and atypical adenomas: systematic review of case reports

BACKGROUND

Pituitary carcinomas (PC) and atypical pituitary adenomas (APA) are rare variants of pituitary tumors for which no evidence-based treatment currently exists. We sought to determine whether temozolomide represents an effective chemotherapeutic option for patients with PC and APA.

METHODS

A systematic review was performed using all published cases of PC and APA treated with temozolomide, and for which information on treatment regimen, clinical response, and survival could be identified. The primary goal of this analysis was to describe overall survival and progression-free survival among PC and APA patients after temozolomide treatment. Secondary goals included assessment of response rate and biomarkers of response.

RESULTS

We identified 57 cases and obtained follow-up data on 54 patients (31 APA and 23 PC) for analysis. Estimates of 5-year progression-free survival and overall survival were 21.9% and 57.4% for patients with APA and 36.1% and 56.2% for patients with PC. Among those who responded to temozolomide, overall survival was marginally statistically significantly greater for patients on long-term temozolomide therapy compared with those who were not (5-year overall survival 91.7% vs 54.1%, P = .08); Progression-free survival results were similar but not statistically significant. The objective response rate was 48.4% for patients with APA and 65.2% for patients with PC. Stable disease occurred in 29% of APA and 17.4% of PC patients. Neither histology nor expression of Ki-67 correlated with response; however, negative O⁶-methylguanine-DNA methyltransferase staining was strongly related to response to temozolomide in patients with APA (P < .001).

CONCLUSIONS

Temozolomide is an effective treatment of both PC and APA, and long-term treatment can be considered for particularly aggressive cases.

Epigenetic Mechanisms Leading to Overexpression of HMGA Proteins in Human Pituitary Adenomas

Overexpression of the high-mobility group A (HMGA)1 and HMGA2 proteins is a feature of all human pituitary adenoma (PAs) subtypes. However, amplification and/or rearrangement of the HMGA2 have been described in human prolactinomas, but rarely in other pituitary subtypes, and no genomic amplification of HMGA1 was detected in PAs. Here, we summarize the functional role of HMGA proteins in pituitary tumorigenesis and the epigenetic mechanisms contributing to HMGA overexpression in these tumors focusing on recent studies indicating a critical role of non-coding RNAs in modulating HMGA protein levels.

Decreased expression of APAF-1 and increased expression of cathepsin B in invasive pituitary adenoma

PURPOSE

Apoptotic protease-activating factor-1 (APAF-1) and cathepsin B are important functional proteins in apoptosis; the former is involved in the intrinsic (mitochondrial) pathway, while the latter is associated with both intrinsic and extrinsic pathways. Changes in the expression of apoptosome-related proteins could be useful indicators of tumor development since a priori defects in the mitochondrial pathway might facilitate the inception and progression of human neoplasms. Our aim was to evaluate the profiles of APAF-1 and cathepsin B in relation with other molecules involved in apoptosis/proliferation and to correlate them with the aggressive behavior of invasive pituitary adenomas.

MATERIALS AND METHODS

APAF-1 and cathepsin B were assessed in tissue samples from 30 patients with pituitary adenomas, of which 16 were functional adenomas and 22 were invasive adenomas.

RESULTS

A positive relationship between high proliferation and invasiveness was observed in invasive pituitary adenomas when compared to their noninvasive counterparts (Ki-67 labeling index - 4.72% versus 1.75%). Decreased expression of APAF-1 was recorded in most of the invasive adenomas with a high proliferation index, while the cathepsin B level was elevated in this group. We have noticed a negative correlation between the low level of APAF-1 and invasiveness (63.63%; P<0.01); at the same time, a positive correlation between cathepsin B expression and invasiveness (59.09%; P<0.01) was found. In all, 81.25% out of the total APAF-1-positive samples were cathepsin B negative (P<0.01); 76.92% out of the total cathepsin B-positive samples were APAF-1-negative (P<0.01). These results were reinforced by an apoptosis protein array examination, which showed inhibition of the extrinsic apoptotic pathway in an invasive pituitary adenoma.

CONCLUSION

A bidirectional-inverted relationship between APAF-1 and cathepsin B expressions was noticed. One might hypothesize that shifting the balance between mediators of cell death could result in changes in tumor behavior.

A Histopathological Study of Multi-hormone Producing Proliferative Lesions in Estrogen-induced Rat Pituitary Prolactinoma

Rats with estrogen-induced prolactin-producing pituitary adenoma (E2-PRLoma) have been employed as an animal model of human PRL-producing pituitary adenoma in a large number of studies. Presently, we found that long-term administration of estrogen to SD rats resulted in the development of E2-PRLomas, some of which included multi-hormone producing nodules. We herein report results of histopathological analyses of these lesions. PRLoma models were created in female SD rats by 22 weeks or longer administration of a controlled-release preparation of estradiol at a dose of 10 mg/kg/2 weeks. Ten of the 11 PRLoma model rats had proliferative nodular lesions composed of large eosinophilic cells like gonadotrophs inside the PRLoma. These lesions were positive for PRL, TSHβ, and α subunits and were negative for GH, LHβ, ACTH, and S-100. Double immunostaining revealed that these large eosinophilic cells showed coexpression of PRL and TSHβ, PRL and α subunits, and TSHβ and α subunits. Those results clarified that long-term estrogen administration to female SD rats induced multi-hormone producing neoplastic pituitary nodules that expressed PRL, TSHβ, and α subunits. We studied these neoplastic nodules obtained by laser microdissection to acquire findings similar to those of the immuno­histochemical analysis. We consider that this animal model is useful for pathogenesis analyses and therapeutic agent development concerning human multi-hormone producing pituitary adenomas.