O-6-Methylguanine-DNA methyltransferase expression is associated with pituitary adenoma tumor recurrence: a systematic meta-analysis

Targeting the Tumor Immune Microenvironment Could Become a Potential Therapeutic Modality for Aggressive Pituitary Adenoma

OBJECT

This study aimed to explore the relationship between the aggressiveness and immune cell infiltration in pituitary adenoma (PA) and to provide the basis for immuno-targeting therapies.

METHODS

One hundred and three patients with PA who underwent surgery at a single institution were retrospectively identified. The infiltration of macrophages and T-lymphocytes was quantitatively assessed.

RESULTS

The number of CD68+ macrophages was positively correlated with Knosp (p = 0.003) and MMP-9 expression grades (p = 0.00). The infiltration of CD163+ macrophages differed among Knosp (p = 0.022) and MMP-9 grades (p = 0.04). CD8+ tumor-infiltrating lymphocytes (TILs) were also positively associated with Knosp (p = 0.002) and MMP-9 grades (p = 0.01). Interestingly, MGMT expression was positively correlated with MMP-9 staining extent (p = 0.000). The quantities of CD8+ TILs (p = 0.016), CD68+ macrophages (p = 0.000), and CD163+ macrophages (p = 0.043) were negatively associated with MGMT expression levels. The number of CD68+ macrophages in the PD-L1 negative group was significantly more than that in the PD-L1 positive group (p = 0.01). The rate of PD-L1 positivity was positively correlated with the Ki-67 index (p = 0.046) and p53 expression (p = 0.029).

CONCLUSION

Targeted therapy for macrophages and CD8+ TILs could be a helpful treatment in the future for aggressive PA. Anti-PD-L1 therapy may better respond to PAs with higher Ki-67 and p53 expression and more infiltrating CD68+ macrophages. Multiple treatment modalities, especially combined with immunotherapy could become a novel therapeutic strategy for aggressive PA.

Correlation Analysis of Magnetic Resonance Imaging Characteristics and Prognosis of Invasive Pituitary Adenomas in Neurosurgery Hospitals

The incidence of pituitary adenoma is second only to glioma and meningioma, and its incidence ranks third among intracranial tumors. Most pituitary adenomas are benign and noninvasive tumors, but invasive pituitary adenomas pose a great threat to human health. In order to explore the risk factors that affect the clinical aggressive behavior of patients with pituitary adenoma, analyze the correlation between different classification methods and clinical aggressive behavior, and lay the foundation for early judgment and individualized treatment of clinical aggressive behavior of patients with pituitary adenoma. We conducted statistical research on patients who were treated for pituitary adenomas in the city's Yangzhou Hongquan Hospital. The results of the study showed that six patients in this study showed aggressiveness in the clinical symptomatic outcome, six patients showed aggressiveness in the serological outcome, and seven patients showed aggressiveness in imaging. In the multimodal classification, the clinical aggressiveness of pituitary adenomas in the invasion + atypical group was significantly higher than that in other groups, and the difference was statistically significant (P < 0.05). The correlation analysis of magnetic resonance imaging features and prognosis of invasive pituitary adenomas were verified to be feasible for the treatment of patients.

Genomic and molecular characterization of pituitary adenoma pathogenesis: review and translational opportunities

OBJECTIVE

Innovations in genomics, epigenomics, and transcriptomics now lay the groundwork for therapeutic interventions against neoplastic disease. In the past 30 years, the molecular pathogenesis of pituitary adenomas has been characterized. This enhanced understanding of the biology of pituitary tumors has potential to impact current treatment paradigms, and there exists significant translational potential for these results. In this review the authors summarize the results of genomics and molecular biology investigations into pituitary adenoma pathogenesis and behavior and discuss opportunities to translate basic science findings into clinical benefit.

METHODS

The authors searched the PubMed and MEDLINE databases by using combinations of the keywords "pituitary adenoma," "genomics," "pathogenesis," and "epigenomics." From the initial search, additional articles were individually evaluated and selected.

RESULTS

Pituitary adenoma growth is primarily driven by unrestrained cell cycle progression, deregulation of growth and proliferation pathways, and abnormal epigenetic regulation of gene expression. These pathways may be amenable to therapeutic intervention. A significant number of studies have attempted to establish links between gene mutations and tumor progression, but a thorough mechanistic understanding remains elusive.

CONCLUSIONS

Although not currently a prominent aspect in the clinical management of pituitary adenomas, genomics and epigenomic studies may become essential in refining patient care and developing novel pharmacological agents. Future basic science investigations should aim at elucidating mechanistic understandings unique to each pituitary adenoma subtype, which will facilitate rational drug design.

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.

Evaluation of prognostic utility of Ki-67, P53, and O-6-methylguanine-DNA methyltransferase expression in pituitary tumors

BACKGROUND OR CONTEXT:

Pituitary adenoma (PA) is the most common pathology of the pituitary gland. Pituitary tumors were historically considered benign, however, from recent advances in pathological and molecular analyses, numerous prognostic markers have been identified, allowing a better characterization of tumor behavior and prediction of response to treatment and recurrences.

AIMS AND OBJECTIVES:

Evaluation of the epidemiological occurrence of pituitary tumors in our center and prediction of the benign, aggressive, or malignant nature of the tumor with the help of immunohistochemical markers (IHC) Ki-67, P53, and O-6-methylguanine-DNA methyltransferase (MGMT) along with radiology.

MATERIALS AND METHODS:

A prospective study was done in 33 cases. Patients with clinically suspected pituitary tumors and related symptoms and signs are referred from the endocrine outpatient department and subsequently operated at the neurosurgery department were selected. We have studied the clinical features, radiology, histopathology, and IHC with the help of Ki-67, P53, and MGMT of PA over 2 years.

RESULTS:

We have 94% (31/33) cases of PA among them 94% (29/31) cases are macroadenoma. The IHC was conducted on 30 cases (excluding 1 case of pituitary apoplexy) where Ki-67, p53, and MGMT have been used for IHC in order to analyze the prognosis of the PA, irrespective of the immunological subtype of the PA. In our study, only 13% (4 patients) had MGMT score 0 and 2 patients, among these 4 patients having above cutoff level of Ki-67 and p53 value, considered as aggressive (in case of Ki-67 >3% and >50% in case of p53). When comparing MGMT expression with recurrence, a high degree of significance was found (Mann–Whitney U-test, P = 0.0038). Most of the recurrent tumors (6/9) had MGMT score 1 or below and most of the nonrecurring tumor had MGMT score 2 or above. When comparing MGMT expression with aggressiveness, a high degree of significance was found (Mann–Whitney U-test, P < 0.0001). Finally, combining the radiological Ki-67, p53, and MGMT values, two cases of aggressive adenoma have been seen in our study, the remaining being benign adenomas (WHO classification 2004). We did not encounter any case of pituitary carcinoma. MGMT did not show any significant correlation with radiological grading and histology.

CONCLUSION:

The benign, aggressive, or malignant nature of PA can be effectively predicted with the help of IHC, such as Ki-67, p53, and MGMT. This helps in better patient management and predicts recurrences and prognosis.

Invited Review: Pathology of pituitary neuroendocrine tumours: present status, modern diagnostic approach, controversies and future perspectives from a neuropathological and clinical standpoint

Neuroendocrine tumours of the adenohypophysis have traditionally been designated as pituitary adenomas to underline their usually indolent growth and lack of metastatic potential. However, they may demonstrate a huge spectrum of growth patterns and endocrine disturbances, some of them significantly affecting health and quality of life. To predict tumour growth, risk of postoperative recurrence and response to medical therapy in patients with pituitary neuroendocrine tumours is challenging. A thorough histopathological and immunohistochemical diagnostic work-up is an obligatory part of a multidisciplinary effort to precisely define the tumour type and assess prognostic and predictive factors on an individual basis. In this review, we have summarized the current status in the pathology in pituitary neuroendocrine tumours based on the selection of references from the PubMed database. We have presented possible diagnostic approaches according to the current pituitary cell lineage-based classification. The importance of recognizing histological subtypes with potentially aggressive behaviour and identification of prognostic and predictive tissue biomarkers have been highlighted. Controversies related to particular subtypes of pituitary tumours and a still limited prognostic impact of the current classification indicate the need for further refinement. Multidisciplinary approach including clinical, pathological and molecular genetic characterization will be essential for improved personalized therapy and the search for novel therapeutic targets in patients with pituitary neuroendocrine tumours.

Recent advances in understanding corticotroph pituitary tumor initiation and progression

Cushing’s disease is the most frequent form of hypercortisolism and is caused by hypophyseal corticotroph adenomas secreting excessive amounts of adrenocorticotropic hormone. Most of the tumors develop sporadically and only a limited number of corticotroph adenomas have been found to be associated with different neuroendocrine syndromes or with familial isolated pituitary adenomas. The pathogenic mechanisms of corticotroph adenomas are largely unknown, but the discovered aberrant chaperoning activity of heat shock protein 90 on the one hand and the presence of ubiquitin-specific protease 8 mutations on the other hand partially explained the causes of their development. Corticotroph tumors arise initially as benign microadenomas but with time form invasively growing aggressive macroadenomas which can switch to corticotroph carcinomas in extremely rare cases. The mechanisms through which corticotroph tumors escape from glucocorticoid negative feedback are still poorly understood, as are the processes that trigger the progression of benign corticotroph adenomas toward aggressive and malignant phenotypes. This review summarizes recent findings regarding initiation and progression of corticotroph pituitary tumors.

65 YEARS OF THE DOUBLE HELIX: Treatment of pituitary tumors with temozolomide: an update

Temozolomide is an alkylating chemotherapeutic agent used in malignant neuroendocrine neoplasia, melanoma, brain metastases and an essential component of adjuvant therapy in the treatment of glioblastoma multiforme and anaplastic astrocytoma. Since 2006, it has been used for the treatment of pituitary carcinomas and aggressive pituitary adenomas. Here, we discuss the current indications and results of temozolomide therapy in pituitary tumors, as well as frequently asked questions regarding temozolomide treatment, duration of therapy, dosage, tumor recurrence and resistance.

The expression profile of PD-L1 and CD8+ lymphocyte in pituitary adenomas indicating for immunotherapy

BACKGROUND

Pituitary adenomas (PAs) are the second most common brain tumors, and mostly are benign tumors. However, there exists subtypes of PAs refractory to common treatments, and need novel therapy. Programmed death 1 (PD-1) blockade has shown durable objective response in a variety of malignancies, and the key predictive markers for this immunotherapy were PD-L1 and CD8⁺ tumor-infiltrating lymphocyte (TILs) expression. To evaluate the potential immunotherapy for PAs, we investigated the expression of these two immune markers in PAs.

METHODS

Immunohistochemistry (IHC) was performed to detect the expression of PD-L1 and CD8⁺ TILs in PAs. The ratio of positive expression of PD-L1 and CD8⁺ TILs was compared with chi-squared tests among different subtypes of PAs. The association between their expression profile and clinical parameters was analyzed using a chi-squared test, or Fisher's exact probability test when appropriate.

RESULTS

One hundred and ninety one patients with PAs were retrospectively involved in this study, consisting of 106 non-functioning PAs (NF-PAs, 55.5%), 40 PRL-secreting PAs (PRL-PAs, 20.9%), 31 GH-secreting PAs (GH-PAs, 16.2%), 9 ACTH-secreting PAs (ACTH-PAs, 4.7%) and 5 plurihormonal adenomas (2.6%) respectively. 36.6% of them were PD-L1 positive and 86.9% were CD8⁺ TILs positive. The positive PD-L1 immunostaining presented more frequently in functioning PAs (58.8%), compared with that (34.3%) in nonfunctioning group (p = 0.000). Moreover, the rates of PD-L1 expression were more associated with increased blood levels of PRL, GH, ACTH and cortisol. Contrastly, positive CD8⁺ TILs immunostaining was only correlated with elevated blood level of GH. For the analysis of immune markers with pathological results, PD-L1 expression was associated with PRL and GH immunostaining and higher Ki-67 index. But CD8⁺ TILs was only correlated with PRL immunostaining.

CONCLUSION

Our results showed that PD-L1 was frequently expressed in functioning PAs with association of aggressive behaviors in PAs. The immunotherapy could be a promising treatment option of PAs.

Malignant transformation in non-functioning pituitary adenomas (pituitary carcinoma)

Non-functioning pituitary carcinomas (NFPC) are defined as tumours of adenophyseal origin with craniospinal or systemic dissemination, with the absence of a hormonal hypersecretion syndrome. These are a histologically heterogenous group of tumours, comprising gonadotroph, null cell, "silent" tumours of corticotroph, somatotroph or lactotroph cell lineages as well as plurihormonal Pit-1 tumours. NFPC are exceedingly rare, and hence few cases have been described. This review has identified 38 patients with NFPC reported in the literature. Recurrent invasive non-functioning pituitary adenomas (NFPA) were observed in a majority of patients. Various factors have been identified as markers of the potential for aggressive behaviour, including rapid tumour growth, growth after radiotherapy, gain or shift of hormone secretion and raised proliferative markers. Typically, there is a latency of several years from the original presentation with an NFPA to identification of metastases and only 5 cases reported with rapidly progressive malignant disease within 1 month of presentation. Therapeutic options include debulking surgery, radiation therapy and chemotherapy with temozolomide recommended as first line systemic treatment. Although long-term survivors are described, prognosis remains generally very poor (median survival 8 months). Improvements in molecular tumour profiling may assist in predicting tumour behaviour, guide therapeutic choices and identify novel therapies.

Histopathological classification of non-functioning pituitary neuroendocrine tumors

Non-functioning pituitary neuroendocrine tumors do not cause endocrine symptoms related to hypersecretion of adenohypophyseal hormones and are clinically characterized by symptoms due to growing sellar tumor mass. Histopathological classification of this tumor group has always been challenging due to their heterogeneity, limited knowledge on their biology, and diverse methodological problems. We have searched PubMed database for data related to the histopathological classification of non-functioning pituitary tumors and methods for its application. Principles of the classification and grading presented in the recently released 4th edition of the World Health Organization classification of endocrine tumors have been summarized. Based on the expression of anterior pituitary hormones and pituitary specific transcription factors, gonadotroph tumors dominate within the group of clinically non-functioning tumors, followed by corticotroph type; however, other less common types of the non-functioning tumors can be identified. Assessment of tumor cell proliferation is important to identify "high-risk adenomas." A few subtypes of non-functioning tumors belong to the category of potentially aggressive tumors, independent of the cell proliferation rate. Here, we present up to date criteria for the classification of clinically non-functioning pituitary tumors, offer a diagnostic approach for the routine clinical use, and emphasize a need for inclusion of prognostic and predictive markers in the classification.