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

Giant prolactinomas, a detailed analysis of 196 adult cases

PURPOSE

Giant prolactinomas are a rare entity, representing approximately 5% of all prolactinomas. A systematic review of 196 adult cases was performed. A comparison of the clinical, biochemical and radiological characteristics, management and therapeutic outcomes in men versus women is made.

METHODS

A structured search was conducted using the term 'giant prolactinoma'. Following inclusion criteria were used: diameter ≥ 40 mm, prolactin levels > 1000 ng/ml and no concomitant GH/ ACTH secretion.

RESULTS

196 cases were included [age: 38 (28-50) years, F/M ratio: 1/3.6]. Median tumor diameter was 53 (43-69) mm. Pituitary deficiency was present in 91% of cases, with hypogonadotropic hypogonadism being the most frequent. Most common presenting symptoms were visual impairment (73%) and headache (50%) in men and amenorrhea (58%) in women. 82% of cases were treated with a dopamine agonist (DA) as first-line treatment which led to normoprolactinemia, tumor shrinkage and visual improvement in 51%, 88% and 85% of cases, respectively. Surgery was performed in 29% of cases and all showed tumor remnant and persistent hyperprolactinemia. Women had a lower prolactin level and a smaller tumor diameter at diagnosis but pituitary deficiencies were more frequent and outcome was worse.

CONCLUSION

Giant prolactinomas are rare and have a male predominance. Visual impairment is the most frequent presenting symptom in men and amenorrhea in women. The gender-related difference in tumor size and level of prolactin was confirmed in this analysis where men had a larger diameter and a higher baseline prolactin level. DAs are the treatment of choice, irrespective of tumor size and presence of visual impairment. As only half of the cases achieved normoprolactinemia we do not, in contrast to previous literature, state giant prolactinomas to be exquisitely sensitive to DAs. Patient characteristics associated with persistent hyperprolactinemia after treatment with a DA were female gender, higher baseline prolactin and larger tumor size . This analysis did show TSH- and ACTH-deficiency to be more frequent after surgery which was not seen for LH/FSH deficiency.

β-Catenin is reduced in membranes of human prolactinoma cells and it is inhibited by temozolomide in prolactin secreting tumor models

INTRODUCTION: Prolactinomas are the most frequent pituitary tumor subtype. Despite most of them respond to medical treatment, a proportion are resistant and become a challenge in clinical management. Wnt/β-Catenin pathway has been implicated in several cancers including pituitary tumors and other sellar region malignancies. Interestingly, Wnt/β-Catenin inhibition augments the cytotoxicity of the chemotherapeutic agent Temozolomide (TMZ) in different cancers. TMZ is now being implemented as rescue therapy for aggressive pituitary adenoma treatment. However, the molecular mechanisms associated with TMZ action in pituitary tumors remain unclear. OBJECTIVES: Our aims in the present study were to evaluate differential β-Catenin expression in human resistant prolactinomas and Wnt/β-Catenin signaling activation and involvement in Prolactin (PRL) secreting experimental models treated with TMZ. RESULTS: We first evaluated by immunohistochemistry β-Catenin localization in human resistant prolactinomas in which we demonstrated reduced membrane β-Catenin in prolactinoma cells compared to normal pituitaries, independently of the Ki-67 proliferation indexes. In turn, in vivo 15 mg/kg of orally administered TMZ markedly reduced PRL production and increased prolactinoma cell apoptosis in mice bearing xenografted prolactinomas. Intratumoral β-Catenin strongly correlated with Prl and Cyclin D1, and importantly, TMZ downregulated both β-Catenin and Cyclin D1, supporting their significance in prolactinoma growth and as candidates of therapeutic targets. When tested in vitro, TMZ directly reduced MMQ cell viability, increased apoptosis and produced G2/M cell cycle arrest. Remarkably, β-Catenin activation and VEGF secretion were inhibited by TMZ in vitro. CONCLUSIONS: We concluded that dopamine resistant prolactinomas undergo a β-Catenin relocalization in relation to normal pituitaries and that TMZ restrains experimental prolactinoma tumorigenicity by reducing PRL production and β-Catenin activation. Together, our findings contribute to the understanding of Wnt/β-Catenin implication in prolactinoma maintenance and TMZ therapy, opening the opportunity of new treatment strategies for aggressive and resistant pituitary tumors.

Aggressive nonfunctioning pituitary neuroendocrine tumors

Nonfunctioning pituitary neuroendocrine tumors (NF-PitNETs) are tumors that are not associated with clinical evidence of hormonal hypersecretion. According to the World Health Organization (WHO), there are some subtypes of PitNETs that exhibit more aggressive behavior than others. Among the types of potentially aggressive PitNETs, three are nonfunctional: silent sparsely granulated somatotropinomas, silent corticotropinomas, and poorly differentiated PIT-1 lineage tumors. Several biological markers have been investigated in NF-PitNETs. However, there is no single biomarker able to independently predict aggressive behavior in NF-PitNETs. Thus, a more complex and multidisciplinary proposal of a comprehensive definition of aggressive NF-PitNETs is necessary. Here, we suggest a combined and more complete criterion for the NF-PitNETs classification. We propose that aggressiveness is due to a multifactorial combination, and we emphasize the need to include new emerging markers that are involved in the aggressiveness of NF-PitNETs and the need to identify.

Pituitary carcinoma - case series and review of the literature

Although pituitary adenomas (PAs) account for 15% of intracranial tumors, pituitary carcinomas (PCs) are a rare entity. Most commonly, PCs evolve from aggressive PAs invading the surrounding structures and eventually leading to metastatic lesions. Due to the low incidence, the diagnosis and treatment remains challenging. We report a case series of five patients with pituitary carcinoma (PC) treated in our center. At first diagnosis 3 patients had an ACTH-producing adenoma, 1 a prolactinoma and 1 a double secreting adenoma (GH and prolactin). The mean time interval from initial diagnosis to diagnosis of PC was 10.7 years (range 5-20 years). All patients underwent multiple surgical resections and radiotherapy. Four patients were treated with temozolomide for metastatic disease. One patient with concomitant radiochemotherapy for local recurrence. Temozolomide led to a stable disease in 2 patients. One patient had a progressive disease after 9 cycles of temozolomide. In absence of standard treatment, immunotherapy was initiated, resulting in a stable disease. We report five cases of PCs. Three patients obtained a stable disease after tailored multidisciplinary treatment. Additionally, one patient was treated with immunotherapy, opening a new treatment option in PCs. Overall, PCs are rare intracranial neoplasms occurring several years after the initial diagnosis of aggressive PAs. Currently, the absence of predictive factors for an aggressive clinical course, provokes a challenging management.

Temozolomide Nonresponsiveness in Aggressive Prolactinomas and Carcinomas: Management and Outcomes

Context

Temozolomide (TMZ) is endorsed as the treatment of choice in aggressive or malignant pituitary adenomas.

Objective

Herein we describe a case of an aggressive prolactinoma that was resistant to TMZ. We performed a literature review of similar nonresponsive, aggressive prolactinomas.

Methods

A 40-year-old woman presented with a giant prolactinoma that required cabergoline, transsphenoidal surgery, and radiotherapy to achieve near-normal prolactin and apparently no residual tumor. A year later, she presented with multiple cranial nerve involvement due to a recurrent tumor extending to the infratemporal fossa. She underwent transfrontal surgery, second radiotherapy, and was started on TMZ. Despite 8 cycles of temozolomide (200 mg/m², 5/28-day cycle), she had progressive disease and ultimately succumbed to the disease. PubMed/MEDLINE, Google Scholar, and prior review articles were searched for manuscripts about patients with aggressive prolactinomas who had been treated with TMZ. Data on demography, duration of therapy, and management outcomes were analyzed in those with progressive disease.

Results

We identified 94 cases of patients with aggressive/malignant prolactinomas in the literature who had received TMZ. Progressive disease despite TMZ was present in 36 cases (38%). There was a male preponderance (65%) among these and 40% had aggressive prolactinomas, whereas the rest had carcinomas. Patients received a median of 8 cycles (interquartile range, 3.5-11.5) of TMZ. O6‐methylguanine‐DNA‐methyltransferase (MGMT) immunostaining was negative in 35%. Overall mortality at the time of publication was 40%, at a duration varying from 2 to 20 years from diagnosis.

Conclusion

TMZ resistance in aggressive/malignant prolactinomas is challenging. Progressive disease on optimal TMZ treatment entails the use of newer agents.

Long-Term Use of Temozolomide as Safe and Effective Therapy for an Aggressive Corticotroph Adenoma in a Very Old Patient

Background

Temozolomide (TMZ) is safe and effective in the treatment of aggressive pituitary adenomas (PAs). However, the optimal duration of TMZ therapy is still unknown. Moreover, data about administration of TMZ in elderly (≥65 years) people to treat aggressive PAs are scarce. We report the case of the oldest female patient undergoing the longest TMZ protocol described so far to treat an aggressive, initially silent corticotroph PA.

Case report

The patient initially underwent partial surgical removal of the PA. Subsequent treatment with cabergoline was applied, but it was unsuccessful in controlling the growth of the residual tumor. Pasireotide and external radiation also showed to be ineffective; therefore, treatment with TMZ was started at the standard dose of 200 mg/m²/day for 5 days every 4 weeks for a total of 47 cycles. At the time of treatment’s beginning, the patient was 83 years old. Radiological follow-up documented a progressive, remarkable reduction of the adenoma and the last imaging, after 39 cycles of TMZ, showed an intrasellar lesion with large areas of cystic degeneration. The patient also developed adrenal deficiency managed with glucocorticoid replacement. No major side effects were observed throughout the treatment, with exception of nausea, well controlled with anti-emetic medication. TMZ therapy was discontinued after 47 cycles; hormonal and imaging follow-up investigations documented sustained functional and dimensional response.

Conclusions

Our case supports the long-term use of TMZ, confirming its safety and efficacy also for elderly patients.

Pituitary Neoplasm Nomenclature Workshop: Does Adenoma Stand the Test of Time?

The WHO Classification of Endocrine Tumours designates pituitary neoplasms as adenomas. A proposed nomenclature change to pituitary neuroendocrine tumors (PitNETs) has been met with concern by some stakeholder groups. The Pituitary Society coordinated the Pituitary Neoplasm Nomenclature (PANOMEN) workshop to address the topic. Experts in pituitary developmental biology, pathology, neurosurgery, endocrinology, and oncology, including representatives nominated by the Endocrine Society, European Society of Endocrinology, European Neuroendocrine Association, Growth Hormone Research Society, and International Society of Pituitary Surgeons. Clinical epidemiology, disease phenotype, management, and prognosis of pituitary adenomas differ from that of most NETs. The vast majority of pituitary adenomas are benign and do not adversely impact life expectancy. A nomenclature change to PitNET does not address the main challenge of prognostic prediction, assigns an uncertain malignancy designation to benign pituitary adenomas, and may adversely affect patients. Due to pandemic restrictions, the workshop was conducted virtually, with audiovisual lectures and written précis on each topic provided to all participants. Feedback was collated and summarized by Content Chairs and discussed during a virtual writing meeting moderated by Session Chairs, which yielded an evidence-based draft document sent to all participants for review and approval. There is not yet a case for adopting the PitNET nomenclature. The PANOMEN Workshop recommends that the term adenoma be retained and that the topic be revisited as new evidence on pituitary neoplasm biology emerges.

Temozolomide cytoreductive treatment in a giant cabergoline-resistant prolactin-secreting pituitary neuroendocrine tumor

Dopamine agonists (DAs, especially cabergoline) are recommended as first-line treatment in patients with prolactin-secreting pituitary adenomas, to reduce hormone secretion and tumor size. Pituitary surgery, suggested in nonresponsive patients, cannot achieve a gross total resection or is not feasible in some cases. Temozolomide (TMZ) has been proposed in patients with aggressive pituitary neuroendocrine tumors (PitNETs) who do not respond to conventional treatments. We present a 47-year-old man with a giant (70×51×64 mm) prolactin-secreting PitNET. Cabergoline treatment (at first 1.5 mg/week, and then increased to 3.5 mg/week after 3 months) achieved prolactin suppression; however, magnetic resonance revealed a stable mass. After explanation of surgical complications, the patient rejected the procedure. Therefore, a primary neoadjuvant cytoreductive TMZ treatment was discussed during a meeting of the Pituitary Multidisciplinary Team, and added to cabergoline. After 13 cycles of TMZ (1 year of treatment), we observed dramatic reduction of the PitNET (from 18 cm of adenoma to 6 cm of necrotic tissue). MRI performed 4, 12, and 18 months after TMZ discontinuation revealed a stable residual PitNET, and 1.5 mg/week of cabergoline has been continued until today. Recently, the criteria for developing Pituitary Tumors Centers of Excellence have been proposed, indicating that a multidisciplinary team is the best care for patients. Surgery, rejected by the patient, could only achieve a partial resection; therefore, we decided to combine TMZ and cabergoline. An early initiation of TMZ could be considered in selected cases, especially when surgery could be only partially effective.

Efficacy of Temozolomide Therapy in Patients With Aggressive Pituitary Adenomas and Carcinomas-A German Survey

CONTEXT

Despite growing evidence that temozolomide (TMZ) therapy is effective for the treatment of aggressive pituitary tumors (APTs) or carcinomas (PCs), individual therapy decisions remain challenging.

OBJECTIVE

We therefore aimed to report on clinical characteristics leading to initiation of TMZ therapy and to add evidence on TMZ long-term effectiveness.

DESIGN AND SUBJECTS

Retrospective survey on TMZ treatment in patients with APTs or PCs. TMZ therapy was initiated in 47 patients (22 females) with APTs (n = 34) or PCs (n = 13). Mean age at diagnosis was 45 ± 15 years. The immunohistochemical subtypes were corticotroph (n = 20), lactotroph (n = 18), and nonfunctioning (n = 9) tumors. TMZ therapy started 8 years after initial diagnosis using a standard regimen (median 6 cycles) for the majority of patients.

RESULTS

Long-term radiological response to TMZ after a median follow-up of 32 months with 4 patients still on TMZ therapy was tumor regression for 9 (20%), stable disease for 8 (17%), and tumor progression for 29 patients (63%) (outcome data available for 46 patients). Progression occurred 16 months after initiation of TMZ. Median estimated progression-free survival was 23 months. Disease stabilization and median progression-free survival did not differ between patients with APTs or PCs. Predictors of tumor response were not identified. Overall, TMZ was well tolerated.

CONCLUSION

We performed a nationwide survey on TMZ therapy in patients with APTs and PCs. While early response rates to TMZ are promising, long-term outcome is less favorable. Prolonged TMZ administration should be considered. We were not able to confirm previously reported predictors of tumor response to TMZ.

Aggressive prolactinomas: how to manage?

PURPOSE

Aggressive prolactinomas are defined as radiologically invasive tumors which cannot be cured by surgery, and that have an unusually rapid rate of tumor growth despite dopamine agonist treatment and surgery. In some cases, metastasis occurs, defining prolactin carcinoma which is the second most frequent pituitary carcinoma.

METHODS

A literature search was performed to review the available data on the treatment of aggressive pituitary prolactinomas or carcinomas.

RESULTS

When optimal standard therapies (high dose cabergoline, surgery and radiotherapy) failed, temozolomide, an alkylating drug, is currently the best option, allowing to control tumor growth in about 50% of treated prolactinomas and improving overall survival of these patients. However, long-term complete response occurs in a limited subgroup of tumors. Alternative drugs could be discussed in a subset of aggressive prolactinomas either before temozolomide (pasireotide, peptide receptor radionuclide therapy…) or after temozolomide failure.

CONCLUSION

Despite the significant improvement obtained with the use of temozolomide, a need for alternative drugs persists since a majority of these tumors are resistant or will recur during the follow-up. Patients suffering from such a rare condition should have access to clinical trials available for other types of rare cancers, such as tyrosine kinase inhibitors or immunotherapy.

Italian Association of Clinical Endocrinologists (AME) and Italian AACE Chapter Position Statement for Clinical Practice: Acromegaly - Part 2: Therapeutic Issues

Any newly diagnosed patient should be referred to a multidisciplinary team experienced in the treatment of pituitary adenomas. The therapeutic management of acromegaly always requires a personalized strategy. Normal age-matched IGF-I values are the treatment goal. Transsphenoidal surgery by an expert neurosurgeon is the primary treatment modality for most patients, especially if there are neurological complications. In patients with poor clinical conditions or who refuse surgery, primary medical treatment should be offered, firstly with somatostatin analogs (SSAs). In patients who do not reach hormonal targets with first-generation depot SSAs, a second pharmacological option with pasireotide LAR or pegvisomant (alone or combined with SSA) should be offered. Irradiation could be proposed to patients with surgical remnants who would like to be free from long-term medical therapies or those with persistent disease activity or tumor growth despite surgery or medical therapy. Since the therapeutic tools available enable therapeutic targets to be achieved in most cases, the challenge is to focus more on the quality of life.

Recurrent Metastasized Parathyroid Carcinoma-Long-Term Remission After Combined Treatments With Surgery, Radiotherapy, Cinacalcet, Zoledronic Acid, and Temozolomide

Parathyroid carcinoma is a rare cause of primary hyperparathyroidism with rather poor prognosis. Apart from surgery, no evidence-based treatments exist. A 48-year-old woman presented with weight loss, nausea, constipation, hypercalcemic crisis, and a recurrent neck tumor 5 years after primary surgery of a parathyroid tumor that primarily was classified as an adenoma. Histopathological reevaluation of the original tumor revealed the correct diagnosis to be parathyroid carcinoma (PC). The patient underwent surgery of the recurrent tumor, which was locally invasive with metastatic spread to the mediastinum and neck lymph nodes. Computed tomography demonstrated large lytic bone lesions in both iliac bones including, on the right, a soft tissue mass compatible with bone metastasis. The patient was treated with cinacalcet, repeated zoledronic acid infusions, and temozolomide cycles for 1 year. She underwent two additional neck surgeries for PC and sternotomy for resection of mediastinal metastases. Massive osteolytic lesions in both femoral necks caused imminent fracture risk and therefore both femurs were prophylactically stabilized by intramedullary nail. Serum calcium normalized after the third neck surgery, cinacalcet was discontinued, and parathyroid hormone gradually normalized during continued treatments with temozolomide, adjuvant radiotherapy, and zoledronic acid, with no signs of active disease on imaging and normal biochemistry. The patient remains in remission 17 years after successful combined treatments for recurrent, metastasized PC. The parathyroid tumor tissue demonstrated high O6-methylguanine DNA methyltransferase (MGMT) promoter methylation status, a known predictor of positive temozolomide treatment response in other tumors. In addition, synergistic effects of multiple treatments may have accounted for the favorable response. © 2018 The Authors. JBMR Plus is published by Wiley Periodicals, Inc. on behalf of the American Society for Bone and Mineral Research.

Aggressive and malignant pituitary tumours: state-of-the-art

Pituitary adenomas are unique in multiple ways. They are rarely malignant in terms of metastases; yet, they may be aggressive. Their cancerous potential is defined in a classic oncological way by the ability to metastasise, and therefore, it has been crucial to differentiate this process from aggressive behaviour, characterised as a particularly invasive and/or recurrent behaviour and resistance to common modalities of therapy. Recently, however, important changes have been introduced to the diagnosis and management of aggressive and malignant pituitary tumours including the 4th edition of the World Health Organization (WHO) classification for endocrine tumours (2017) as well as ESE Clinical Guidelines (2018), although an attempt to establish predictive and/or prognostic markers of clinical aggressiveness remains difficult. In this review, we focus on a group of pituitary tumours causing significant problems in clinical practice and requiring multidisciplinary input. We summarise updates in definitions of tumour invasiveness, aggressiveness and malignant transformation, as well as histological classification, and emphasise the new considerations regarding aggressive and malignant potential and its relationship to therapeutic strategies.

Effective long-term temozolomide rechallenge in a macroprolactinoma

We describe the 20-year course of a 63-year-old male with a macroprolactinoma that acquired resistance to treatment and aggressive behavior after a 4-year successful treatment with cabergoline. He was submitted to multiple surgical resections by a skilled surgeon, fractionated radiotherapy and was eventually treated with temozolomide. After a first 6-month standard cycle, a relapse occurred and he was treated again successfully.

Temozolomide and Pituitary Tumors: Current Understanding, Unresolved Issues, and Future Directions

Temozolomide, an alkylating agent, initially used in the treatment of gliomas was expanded to include pituitary tumors in 2006. After 12 years of use, temozolomide has shown a notable advancement in pituitary tumor treatment with a remarkable improvement rate in the 5-year overall survival and 5-year progression-free survival in both aggressive pituitary adenomas and pituitary carcinomas. In this paper, we review the mechanism of action of temozolomide as alkylating agent, its interaction with deoxyribonucleic acid repair systems, therapeutic effects in pituitary tumors, unresolved issues, and future directions relating to new possibilities of targeted therapy.