Treatment with octreotide LAR in clinically non-functioning pituitary adenoma: results from a case-control study

Hybrid Somatostatin Receptor PET/MRI of the Head and Neck

Hybrid PET/MRI has the potential to transform neuro-oncologic imaging, particularly in diagnosis and treatment planning of somatostatin receptor-expressing tumors of the head and neck. Hybrid PET/MRI combines high-resolution MRI with functional information from PET, providing precise anatomic information and overcoming difficulties in localization inherent to PET alone. There is a range of tumors in the head and neck that overexpress somatostatin receptors and are therefore amenable to evaluation with somatostatin receptor PET/MRI. These include meningiomas, paragangliomas, olfactory neuroblastomas, pituitary neuroendocrine tumors, middle ear neuroendocrine tumors, and medullary thyroid carcinomas. The combination of PET and MRI is superior to either modality alone and can address several unique diagnostic challenges associated with these lesions. The authors discuss the superior capabilities of somatostatin receptor PET/MRI, including improved lesion localization, more sensitive demonstration of disease extent, enhanced surveillance, optimized radiation therapy planning, and accurate prediction of response to somatostatin analog therapy. Although there are only a few dedicated PET/MRI units available in clinical practice, commercial software is now available that can automatically fuse PET/CT data with recently acquired MRI data, increasing the availability of this approach. Radiologists should be aware of the advantages of somatostatin receptor PET/MRI in evaluation of head and neck tumors as well as the potential pitfalls of this approach so that they can accurately advise clinicians and better interpret these studies. ©RSNA, 2024 See the invited commentary by Shatzkes and Strauss in this issue.

Treatment of an Aggressive Gonadotroph Pituitary Neuroendocrine Tumor With 177Lutetium DOTATATE Radionuclide Therapy

Aggressive pituitary neuroendocrine tumors (PitNETs) present significant morbidity, and multimodal therapies including surgery, radiotherapy, and medications are frequently required. Chemotherapy, particularly temozolomide, is often pursued for tumors that progress despite these treatments. Although peptide receptor radionuclide therapy (PRRT) using radiolabeled somatostatin analogs is approved for the treatment of well-differentiated gastrointestinal neuroendocrine tumors, its use in aggressive PitNETs is limited. We describe the case of a 65-year-old man who presented with vision changes and hypopituitarism at age 33 secondary to a nonfunctioning gonadotroph PitNET. His initial treatment included a craniotomy followed by radiation therapy. With tumor regrowth, he required transsphenoidal surgeries at age 44 and age 52. At age 56, further tumor regrowth and a positive octreotide scan prompted treatment with long-acting octreotide for 1 year. Given absent tumor response, 12 cycles (4 treatment cycles and 8 maintenance cycles) of PRRT with 177Lutetium-DOTATATE were pursued. This resulted in partial response with significant tumor shrinkage. Notably, there was no tumor regrowth 40 months after treatment discontinuation. This is only the second report on the effectiveness of PRRT in patients with aggressive gonadotroph PitNETs. We also provide an overview of PRRT for PitNETs and describe clinical outcomes previously reported in the literature.

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.

Association between Intracellular Calcium Signaling and Tumor Recurrence in Human Non-Functioning Pituitary Adenomas

Clinically non-functioning pituitary adenomas (CNFPAs) are the second most frequent sellar tumor among studies on community-dwelling adults. They are characterized by the absence of hormonal hypersecretion syndrome, and patients present with compressive symptoms, such as a headache and visual field defects. Immunohistochemically, most CNFPAs are of gonadotrope differentiation, with only a few of them being truly null cell adenomas. Although these tumors express receptors for one or more hypothalamic releasing hormones, to what extent this has an impact on the biological and clinical behavior of these neoplasms remains to be defined. In this research, we evaluated the basal and hypothalamic secretagogue-stimulated intracellular calcium mobilization in 13 CNFPAs, trying to correlate this response to the phenotypic features of the patients. Our results indicate that the recurrence of a CNFPA correlates positively with cellular responsiveness, as measured by spontaneous intracellular calcium activity and the ability to respond to multiple hypothalamic secretagogues. We conclude that this finding may be a useful tool for predicting the clinicopathologic behavior of CNFPAs, by testing the variation of cellular responsiveness to hypothalamic secretagogues.

Somatostatin and Somatostatin Receptors in Tumour Biology

Somatostatin (SST), a growth hormone inhibitory peptide, is expressed in endocrine and non-endocrine tissues, immune cells and the central nervous system (CNS). Post-release from secretory or immune cells, the first most appreciated role that SST exhibits is the antiproliferative effect in target tissue that served as a potential therapeutic intervention in various tumours of different origins. The SST-mediated in vivo and/or in vitro antiproliferative effect in the tumour is considered direct via activation of five different somatostatin receptor subtypes (SSTR1-5), which are well expressed in most tumours and often more than one receptor in a single cell. Second, the indirect effect is associated with the regulation of growth factors. SSTR subtypes are crucial in tumour diagnosis and prognosis. In this review, with the recent development of new SST analogues and receptor-specific agonists with emerging functional consequences of signaling pathways are promising therapeutic avenues in tumours of different origins that are discussed.

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.

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.

Somatostatin Receptor-PET/CT/MRI of Head and Neck Neuroendocrine Tumors

BACKGROUND AND PURPOSE

Due to its high sensitivity, somatostatin receptor-PET may detect smaller lesions and more extensive disease than contrast-enhanced MR imaging, while the superior spatial resolution of MR imaging enables lesions to be accurately localized. We compared results of somatostatin receptor-PET/MRI with those of MR imaging alone and assessed the added value of vertex-to-thigh imaging for head and neck neuroendocrine tumors.

MATERIALS AND METHODS

Somatostatin receptor-PET/CT was acquired as limited brain or head and neck imaging, with optional vertex-to-thigh imaging, following administration of 64CU/68GA DOTATATE. Somatostatin receptor-PET was fused with separately acquired contrast-enhanced MR imaging. DOTATATE activity was classified as comparable, more extensive, and/or showing additional lesions compared with MR imaging. Vertex-to-thigh findings were classified as positive or negative for metastatic disease or incidental.

RESULTS

Thirty patients (with 13 meningiomas, 11 paragangliomas, 1 metastatic papillary thyroid carcinoma, 1 middle ear neuroendocrine adenoma, 1 external auditory canal mass, 1 pituitary carcinoma, 1 olfactory neuroblastoma, 1 orbital mass) were imaged. Five had no evidence of somatostatin receptor-positive lesions and were excluded. In 11/25, somatostatin receptor-PET/MRI and MR imaging were comparable. In 7/25, somatostatin receptor-PET/MRI showed more extensive disease, while in 9/25, somatostatin receptor-PET/MRI identified additional lesions. On vertex-to-thigh imaging, 1 of 17 patients was positive for metastatic disease, 8 of 17 were negative, and 8 of 17 demonstrated incidental findings.

CONCLUSIONS

Somatostatin receptor-PET detected additional lesions and more extensive disease than contrast-enhanced MR imaging alone, while vertex-to-thigh imaging showed a low incidence of metastatic disease. Somatostatin receptor-PET/MRI enabled superior anatomic delineation of tumor burden, while any discrepancies were readily addressed. Somatostatin receptor-PET/MRI has the potential to play an important role in presurgical and radiation therapy planning of head and neck neuroendocrine tumors.

[68 Ga]-DOTATATE PET/MR-based evaluation of physiologic somatostatin receptor 2 expression in the adult pituitary gland as a function of age and sex in a prospective cohort

PURPOSE

The pituitary gland has the fourth highest physiologic avidity of [68 Ga]-DOTATATE. In order to guide our understanding of [68 Ga]-DOTATATE PET in clinical contexts, accurate characterization of the normal pituitary gland is first required. This study aimed to characterize the normal pituitary gland using dedicated brain [68 Ga]-DOTATATE PET/MRI as a function of age and sex.

METHODS

A total of 95 patients with a normal pituitary gland underwent brain [68 Ga]-DOTATATE PET examinations for the purpose of diagnosing CNS SSTR2 positive tumors (mean age: 58.9, 73% female). Maximum SUV of the pituitary gland was obtained in each patient. SUV of superior sagittal sinus was obtained to calculate normalized SUV score (SUVR) of the gland. The anatomic size of the gland was collected as maximum sagittal height (MSH). Correlations with age and sex were analyzed.

RESULTS

The mean SUV and SUVR of the pituitary gland were 17.6 (range: 7-59.5, SD = 7.1) and 13.8 (range: 3.3-52.6, SD = 7.2), respectively. Older females had significantly higher SUV of the pituitary gland compared to younger females. When stratified by age and sex, both older and younger females had significantly higher pituitary SUV than older males. SUVR did not differ significantly by age or sex. MSH of the pituitary gland in younger females was significantly greater than in younger males at all age cutoffs.

CONCLUSION

This study provides an empiric profiling of the physiological [68 Ga]-DOTATATE avidity of the pituitary gland. The findings suggest that SUV may vary by age and sex and can help guide the use of [68 Ga]-DOTATATE PET/MRI in clinical and research settings. Future studies can build on these findings to investigate further the relationship between pituitary biology and demographic factors.

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.

Recent advancements in the molecular biology of pituitary adenomas

INTRODUCTION

Pituitary adenomas are a common and diverse group of intracranial tumors arising from the anterior pituitary that are usually slow-growing and benign, but still pose a significant healthcare burden to patients. Additionally, they are increasing in both incidence and prevalence, leading to a need for better understanding of molecular changes in the development of these tumors.

AREAS COVERED

A PubMed literature search was conducted using the terms 'pituitary adenoma' in combination with keywords related to secretory subtype: lactotroph, somatotroph, corticotroph, gonadotroph and null cell, in addition to their transcription factor expression: PIT1, TPIT, and SF-1. Articles resulting from this search were analyzed, as well as relevant articles cited as their references. In this review, we highlight recent advances in the genetic and epigenetic characterization of individual pituitary adenoma subtypes and the effect it may have on guiding future clinical treatment of these tumors.

EXPERT OPINION

Understanding the molecular biology of pituitary adenomas is a fundamental step toward advancing the treatment of these tumors. Yet crucial knowledge gaps exist in our understanding of the underlying molecular biology of pituitary adenomas which can potentially be addressed by turning to differentially activated molecular pathways in tumor relative to normal gland.

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.

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.

Treatment of Aggressive Pituitary Adenomas: A Case-Based Narrative Review

Management of aggressive pituitary adenomas is challenging due to a paucity of rigorous evidence supporting available treatment approaches. Recent guidelines emphasize the need to maximize standard therapies as well as the use of temozolomide and radiation therapy to treat disease recurrence. However, often these adenomas continue to progress over time, necessitating the use of additional targeted therapies which also impact quality of life and long-term outcomes. In this review, we present 9 cases of aggressive pituitary adenomas to illustrate the importance of a multidisciplinary, individualized approach. The timing and rationale for surgery, radiation therapy, temozolomide, somatostatin receptor ligands, and EGFR, VEGF, and mTOR inhibitors in each case are discussed within the context of evidence-based guidelines and clarify strategies for implementing an individualized approach in the management of these difficult-to-treat-adenomas.

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.

The GALANT trial: study protocol of a randomised placebo-controlled trial in patients with a 68Ga -DOTATATE PET-positive, clinically non-functioning pituitary macroadenoma on the effect of lan reotide on t umour size

INTRODUCTION

At present, there is no approved medical treatment option for patients with non-functioning pituitary adenoma. A number of open-label studies suggest that treatment with somatostatin analogues may prevent tumour progression. In vivo somatostatin receptor imaging using ⁶⁸Ga-DOTATATE PET (PET, positron emission tomography) could help in preselecting patients potentially responsive to treatment. Our aim is to investigate the effect of the somatostatin analogue lanreotide as compared with placebo on tumour size in patients with a ⁶⁸Ga-DOTATATE PET-positive non-functioning pituitary macroadenoma (NFMA).

METHODS AND ANALYSIS

The GALANT study is a multicentre, randomised, double-blind, placebo-controlled trial in adult patients with a suprasellar extending NFMA. Included patients undergo a ⁶⁸Ga-DOTATATE PET/CT of the head and tracer uptake is assessed after coregistration with pituitary MRI. Forty-four patients with a ⁶⁸Ga-DOTATATE PET-positive NFMA are randomised in a 1:1 ratio between lanreotide 120 mg or placebo, both administered as subcutaneous injections every 28 days for 72 weeks. The primary outcome is the change in cranio-caudal tumour diameter on pituitary MRI after treatment. Secondary outcomes are change in tumour volume, time to tumour progression, change in quality of life and number of adverse events. Final results are expected in the second half of 2021.

ETHICS AND DISSEMINATION

The study protocol has been approved by the Medical Research Ethics Committee of the Academic Medical Centre (AMC) of the Amsterdam University Medical Centres and by the Dutch competent authority. It is an investigator-initiated study with financial support by Ipsen Farmaceutica BV. The AMC, as sponsor, remains owner of all data. Results will be submitted for publication in a peer-reviewed journal.

TRIAL REGISTRATION NUMBER

NL5136 (Netherlands Trial Register); pre-recruitment.

Somatostatin analogues in the therapy of neuroendocrine tumors: Indications, contraindications, side-effects

The presence of somatostatin receptors (SSTRs) is crucial in planning the therapy of patients with neuroendocrine tumors. This applies especially to patients in whom surgery has proven unsuccessful or there are contraindications for it. Increased SSTR expression has been observed in many cancers originating in the neuroendocrine system. Among them we distinguish anterior pituitary adenomas producing GH in excess and leading to the development of acromegaly, adenocorticotropic adenomas that autonomously synthesize ACTH, which leads to the development of ACTH-dependent Cushing’s syndrome (Cushing’s disease), as well as adenomas of the anterior pituitary from thyrotropic cells. Rich expression of these receptors has been confirmed in epithelial tumors of neuroendocrine origin in the gastrointestinal tract, pancreas and lungs. Somatostatin analogues, also called somatostatin receptor ligands, are effective in symptomatic therapy; they enable disease control, exhibit anti-proliferative effects and allow hormonal balance, which reduces mortality among patients and improves their quality of life. The antitumor effect of somatostatin analogues has been proven in in vitro and in vivo studies. In therapy they are usually well tolerated and safe. For many years, somatostatin analogues have maintained an important place in the treatment of neuroendocrine tumors and are still the subject of many studies. The aim of the study is to analyze, based on available literature, therapeutic indications for the use of somatostatin analogues, taking into account contraindications for therapy and its possible side effects.

The tumour microenvironment of pituitary neuroendocrine tumours

The tumour microenvironment (TME) includes a variety of non-neoplastic cells and non-cellular elements such as cytokines, growth factors and enzymes surrounding tumour cells. The TME emerged as a key modulator of tumour initiation, progression and invasion, with extensive data available in many cancers, but little is known in pituitary tumours. However, the understanding of the TME of pituitary tumours has advanced thanks to active research in this field over the last decade. Different immune and stromal cell subpopulations, and several cytokines, growth factors and matrix remodelling enzymes, have been characterised in pituitary tumours. Studying the TME in pituitary tumours may lead to a better understanding of tumourigenic mechanisms, identification of biomarkers useful to predict aggressive disease, and development of novel therapies. This review summarises the current knowledge on the different TME cellular/non-cellular elements in pituitary tumours and provides an overview of their role in tumourigenesis, biological behaviour and clinical outcomes.

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.

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.

68Ga-DOTATATE PET imaging in clinically non-functioning pituitary macroadenomas

Purpose

Clinically non-functioning pituitary macroadenomas (NFMA) have been reported to express somatostatin receptors (SSTR), but results are inconsistent across different studies. This may be related to limited sensitivity and specificity of techniques used to date, i.e. immunohistochemistry in surgical specimens and ¹¹¹In-DTPA-octreotide scintigraphy in vivo. The aim of this study was to assess SSTR expression in NFMA in vivo using ⁶⁸Ga-DOTATATE PET, which offers superior sensitivity and spatial resolution as compared with planar scintigraphy or SPECT.

Methods

Thirty-seven patients diagnosed with NFMA underwent ⁶⁸Ga-DOTATATE PET/CT of the head in the framework of a randomised controlled trial assessing the effect of the somatostatin analogue lanreotide on NFMA size. Individual co-registered T1-weighted pituitary MRIs were used to assess ⁶⁸Ga-DOTATATE uptake (SUV_mean) in the adenoma. An SUV_mean of > 2 was considered positive.

Results

⁶⁸Ga-DOTATATE uptake was positive in 34/37 patients (92%), with SUV_mean of positive adenomas ranging from 2.1 to 12.4 (mean ± SD 5.8 ± 2.6).

Conclusions

This is the first report of ⁶⁸Ga-DOTATATE PET performed in NFMA patients, demonstrating in vivo SSTR expression in the vast majority of cases. The high positivity rate when compared with results obtained with ¹¹¹In-DTPA-octreotide scintigraphy probably reflects the superior sensitivity of PET imaging.

Trial registration

Netherlands Trial Register, NL5136, registered on 18 August 2015; EudraCT, 2015-001234-22, registered on 10 March 2015, https://eudract.ema.europa.eu/

The pituitary in nuclear medicine imaging

The pituitary is an endocrine gland with ability to uptake diverse radiopharmaceuticals and, therefore, susceptible to be investigated by nuclear medicine diagnostic procedures. Although this topic has been scarcely scrutinized, we have data indicating that somatostatin receptor scintigraphy with¹¹¹In-DTPA-D-Phe-octreotide or ^99mTc-EDDA/HYNIC-TOC may be of clinical utility in the diagnosis of some pituitary adenomas (PA). Only a few studies have evaluated the diagnostic performance of ^99mTc-MIBI and ^99mTc (V)-DMSA scintigraphy in pituitary disease. Scintigraphy using ¹²³I-methoxybenzamide (¹²³I-IBZM) might be useful in macroprolactinomas expressing dopamine D2 receptors. Pituitary gland does not usually accumulate 2-deoxy-2-[¹⁸F]fluoro-d-glucose (¹⁸F-FDG) and, therefore, it is not visualized on positron emission tomography (PET) imaging studies with this radiotracer. The pituitary uptake on¹⁸F-FDG PET/CT scans performed in the follow-up of oncological patients are uncommon. However, 60% of these incidental findings are due to PA, mainly non-functioning pituitary macroadenomas, and a small percentage to metastases or other pituitary lesions. Interestingly, ¹⁸F-FDG PET/CT may identify hypophysitis induced by different immunotherapeutic agents used in cancer patients. Positive ¹⁸F-FDG uptake has been reported in a high percentage of patients with PA, mainly macroadenomas and it seems that there is correlation between tumor size and SUVmax. ⁶⁸Ga-DOTA-TATE PET/CT may identify functioning and non-functioning PA, although this technique is more useful in the detection of remaining normal pituitary tissue after transsphenoidal adenomectomy, and in the confirmation of recurrence of functioning PA, such as thyrotroph-secreting PA. Furthermore, ⁶⁸Ga-DOTA-TATE uptake has potential therapeutic implications on molecular-targeted therapy. Lastly, other radiopharmaceuticals that have shown to be taken up in some patients with pituitary disease include ¹⁸F-DOPA (prolactinoma), ¹¹C-methionine (residual or recurrent PA), O-(2-¹⁸F-fluoroethyl)-l-tyrosine (metastasis), ¹⁸F-choline (silent adenoma, ectopic corticotropinoma), and ¹³N-ammonia (hypopituitarism).

Clinical and Pathological Aspects of Silent Pituitary Adenomas

CONTEXT

Silent pituitary adenomas are anterior pituitary tumors with hormone synthesis but without signs or symptoms of hormone hypersecretion. They have been increasingly recognized and represent challenging diagnostic issues.

EVIDENCE ACQUISITION

A comprehensive literature search was performed using MEDLINE and EMBASE databases from January 2000 to March 2018 with the following key words: (i) pituitary adenoma/tumor and nonfunctioning; or (ii) pituitary adenoma/tumor and silent. All titles and abstracts of the retrieved articles were reviewed, and recent advances in the field of silent pituitary adenomas were summarized.

EVIDENCE SYNTHESIS

The clinical and biochemical picture of pituitary adenomas reflects a continuum between functional and silent adenomas. Although some adenomas are truly silent, others will show some evidence of biochemical hypersecretion or could have subtle clinical signs and, therefore, can be referred to as clinically silent or "whispering" adenomas. Silent tumors seem to be more aggressive than their secreting counterparts, with a greater recurrence rate. Transcription factors for pituitary cell lineages have been introduced into the 2017 World Health Organization guidelines: steroidogenic factor 1 staining for gonadotroph lineage; PIT1 (pituitary-specific positive transcription factor 1) for growth hormone, prolactin, and TSH lineage, and TPIT for the corticotroph lineage. Prospective studies applying these criteria will establish the value of the new classification.

CONCLUSIONS

A concise review of the clinical and pathological aspects of silent pituitary adenomas was conducted in view of the new World Health Organization classification of pituitary adenomas. New classifications, novel prognostics markers, and emerging imaging and therapeutic approaches need to be evaluated to better serve this unique group of patients.

Medical therapy for non-functioning pituitary tumors-a critical approach

Non-functioning pituitary adenomas (NFPAs) are the second most common variant of pituitary tumors. When symptomatic, primary therapy is surgery. Recurrence rates are high. Since many NFPAs express dopamine and somatostatin receptors, medical therapy has been used after surgery in order to prevent recurrence. So far, dopamine agonists have been more widely tested with some promise when introduced immediately after surgery but with less efficacy when introduced later upon tumor regrowth. Currently, the role of medical therapy to prevent tumor regrowth in NFPAs is limited by imprecisions as to final outcome and uncertainties concerning on patient selection, dosing, duration, and side effects.

The Treatment of Refractory Pituitary Adenomas

Refractory pituitary adenomas (PAs) are defined as aggressive-invasive PAs characterized by a high Ki-67 index, rapid growth, frequent recurrence, and resistance to conventional treatments. It is notoriously difficult to manage refractory PAs because the efficacy of current therapeutic options is limited. The purpose of this review is to address currently employed and promising therapeutic strategies for the treatment of refractory PAs. Except for prolactinomas, neurosurgery is the first-line option, but most refractory PAs often recur or re-grow after initial surgery and require further treatments. Medical therapy, radiotherapy and re-operation are explored when surgery has failed to completely resect tumors; however, refractory PAs are usually resistant to these treatments. As a salvage treatment, temozolomide (TMZ) has shown promising results and is currently used for all types of refractory PAs. However, not all refractory PAs are responsive to TMZ treatment, and some of these PAs are resistant to TMZ. Although targeted therapies such as vascular endothelial growth factor, epidermal growth factor and mTOR inhibitors have also been used to treat refractory PAs, the effectiveness of these targeted therapies is still not known due to a lack of data from randomized prospective trials. As a novel therapeutic method, cancer immunotherapy is a promising strategy for the treatment of refractory PAs, but further preclinical research and clinical trials are needed to assess the efficacy of this new approach. In summary, early identification and a multidisciplinary approach are required to treat refractory PAs.

Silent somatotroph pituitary adenomas: an update

Silent growth hormone adenomas (SGHA) are a rare entity of non-functioning pituitary neuroendocrine tumors. Diagnosis is invariably made post-operatively of a tumor immunopositive for GH (and Pit-1 in selected cases) but without clinical acromegaly. Mainly young females are affected, and tumors are often uncovered by investigation for headaches or oligoamenorrhea. Integration of clinical, pathological and biochemical data is required for proper diagnosis. Beside normal IGF-1 levels, a third of SGHAs displays elevated GH levels and some will eventually progress to acromegaly. Almost two-thirds will be mixed GH-prolactin tumors and sparsely-granulated monohormonal GH tumors seems the more aggressive subtype. Recurrence and need for radiation is higher than other non-functioning tumors so close follow-up is warranted.

Management of NFAs: medical treatment

INTRODUCTION

Non-functioning pituitary adenomas (NFPAs) are in general large tumors that present with symptoms secondary to local pressure on adjacent structures. Transsphenoidal surgery is the first line of treatment but residual tumor mass is often detected post-operatively. Medical therapy, in any stage of tumor management, is not well established.

METHODS

A literature search was performed to review the available data on medical treatment of NFPAs.

RESULTS

Medications investigated for the treatment of NFPAs include dopamine receptor agonists (DA) and somatostatin receptor ligands. Randomized controlled trials are lacking, but available data suggest that DA have a positive effect on tumor remnant stabilization after surgery and could be considered in this setting. Temozolomide is reserved for aggressive tumors, although future studies are required.

CONCLUSIONS

NFPA are often not amenable to complete surgical resection. Conservative follow-up after surgery is associated with a high prevalence of tumor remnant progression. DA therapy may prevent residual tumor enlargement in over 85% of these patients, with a substantial consequent reduction in the need for repeat surgery or radiation therapy. It is our view that DA treatment should be routinely considered for the management of NFPA patients with incompletely resected tumors.

MANAGEMENT OF ENDOCRINE DISEASE: Present and future perspectives for medical therapy of nonfunctioning pituitary adenomas

In contrast to the clear indication for surgical treatment in symptomatic patients with clinically nonfunctioning pituitary adenomas (NFPA), there are no randomized controlled studies comparing therapeutic strategies such as watchful waiting, irradiation or medical therapy for the management of NFPA after surgery. Further, no medical therapy is currently approved for the treatment of NFPA. In this review, we summarize accumulating data on medications currently approved for secreting pituitary adenomas, used off-label in patients with NFPA. Perspectives on overall treatment optimization and potential future therapies are also detailed.

Dopamine receptor type 2 (DRD2) and somatostatin receptor type 2 (SSTR2) agonists are effective in inhibiting proliferation of progenitor/stem-like cells isolated from nonfunctioning pituitary tumors

The role of progenitor/stem cells in pituitary tumorigenesis, resistance to pharmacological treatments and tumor recurrence is still unclear. This study investigated the presence of progenitor/stem cells in non-functioning pituitary tumors (NFPTs) and tested the efficacy of dopamine receptor type 2 (DRD2) and somatostatin receptor type 2 (SSTR2) agonists to inhibit in vitro proliferation. They found that 70% of 46 NFPTs formed spheres co-expressing stem cell markers, transcription factors (DAX1, SF1, ERG1) and gonadotropins. Analysis of tumor behavior showed that spheres formation was associated with tumor invasiveness (OR = 3,96; IC: 1.05-14.88, p = 0.036). The in vitro reduction of cell proliferation by DRD2 and SSTR2 agonists (31 ± 17% and 35 ± 13% inhibition, respectively, p < 0.01 vs. basal) occurring in about a half of NFPTs cells was conserved in the corresponding spheres. Accordingly, these drugs increased cyclin-dependent kinase inhibitor p27 and decreased cyclin D3 expression in spheres. In conclusion, they provided further evidence for the existence of cells with a progenitor/stem cells-like phenotype in the majority of NFPTs, particularly in those with invasive behavior, and demonstrated that the antiproliferative effects of dopaminergic and somatostatinergic drugs were maintained in progenitor/stem-like cells.

Octreotide and pasireotide (dis)similarly inhibit pituitary tumor cells in vitro

Somatostatin analogs (SSA) are the mainstay of pharmacological treatment for pituitary adenomas. However, some patients escape from therapy with octreotide, a somatostatin receptor 2 (sst2)-preferring SSA, and pasireotide, a novel multi-sst-preferring SSA, may help to overcome this problem. It has been proposed that correspondence between sst1-sst5 expression pattern and SSA-binding profile could predict patient's response. To explore the cellular/molecular features associated with octreotide/pasireotide response, we performed a parallel comparison of their in vitro effects, evaluating sst1-sst5 expression, intracellular Ca²⁺ signaling ([Ca²⁺]_i), hormone secretion and cell viability, in a series of 85 pituitary samples. Somatotropinomas expressed sst5>sst2, yet octreotide reduced [Ca²⁺]_i more efficiently than pasireotide, while both SSA similarly decreased growth hormone release/expression and viability. Corticotropinomas predominantly expressed sst5, but displayed limited response to pasireotide, while octreotide reduced functional endpoints. Non-functioning adenomas preferentially expressed sst3 but, surprisingly, both SSA increased cell viability. Prolactinomas mainly expressed sst1 but were virtually unresponsive to SSA. Finally, both SSA decreased [Ca²⁺]_i in normal pituitaries. In conclusion, both SSA act in vitro on pituitary adenomas exerting both similar and distinct effects; however, no evident correspondence was found with the sst1-sst5 profile. Thus, it seems plausible that additional factors, besides the simple abundance of a given sst, critically influence the SSA response.

Non-functioning pituitary adenomas: growth and aggressiveness

Pituitary adenomas (PAs) are common, comprising approximately one third of all intracranial tumors. Non-functioning pituitary adenomas (NFPAs) are the most common PAs. Although usually benign, the NFPAs represent therapeutic challenges because of their location close to the optic chiasm and nerves, and the proximity to the pituitary gland. The therapeutic alternatives are surgery and radiation. To date there is no effective medical treatment. NFPAs are classified according to different modalities, but there are no reliable marker of aggressiveness to guide the clinician in monitoring the patient. More information on growth patterns with constituent biological markers are needed to tailor the care of this patient group. Studies characterizing the membrane receptors of NFPAs have shown promising results, which may give rise to the development of medical treatment.

Silent pituitary adenomas

Pituitary adenomas are frequently silent. Among silent adenomas, some are clinically silent but can be detected on the basis of the excessive secretion of hormonal products, whereas others are totally silent and cannot be detected by hormonal measurements. Treatment of a silent pituitary adenoma depends on its size and extent. Silent adenomas that are associated with neurologic compromise should be treated by surgery. Postoperative radiation therapy may be used to prevent or treat recurrences. Only occasional silent pituitary adenomas respond to treatment with dopamine agonists or somatostatin analogs.

Dopamine 2 and somatostatin 1-5 receptors coexpression in clinically non-functioning pituitary adenomas

This study investigated quantitated expression of dopamine 2 receptor (D2R) and somatostatin receptors of the five types (SSTR1-SSTR5) in a large series of clinically non-functioning pituitary adenomas (CNFAs). Co-expression of these receptors in individual adenomas was studied as well as correlation between receptor types. Adenoma tissue from 198 patients who underwent surgery for CNFAs was analyzed by immunohistochemistry and quantitative real-time PCR. D2R and SSTR1-3 mRNA was expressed in all 198 adenomas. SSTR4 and SSTR5 were detectable in 85 % and 61 % of adenomas, respectively. Expression of D2R was significantly higher than that of the somatostatin receptors. The median relative expressions were as follows from highest D2R >> SSTR3 > SSTR2 > SSTR1 > SSTR5 > SSTR4. High relative expression (ratio to beta-glucuronidase mRNA > 1) of D2R was found in 60 % of tumors, high expression of SSTR1 in 7.5 %, SSTR2 in 7 %, SSTR3 in 4 % and SSTR5 in 0.5 %. The quantity of D2R correlated positively with expression of SSTR2 and SSTR3, and negatively with SSTR1 and SSTR5. Among histological adenoma types, SSTR1 was significantly higher in null-cell adenomas and SSTR3 was lower in silent corticotroph adenomas. In conclusions, in CNFAs, high expression of somatostatin receptors is much less common than that of D2R, and co-expression of both these receptors is exceptional. D2R and SSTR3 seem to be the most promising targets for pharmacological treatment.

Peptide receptor radionuclide therapy for aggressive atypical pituitary adenoma/carcinoma: variable clinical response in preliminary evaluation

PURPOSE

There are limited treatment options for progressive atypical pituitary adenomas and carcinomas. Peptide receptor radionuclide therapy that targets somatostatin receptors has recently been proposed as a potential treatment option. The theoretical rationale for efficacy is elegant but evaluation of outcomes in the first patients treated for this indication is required to assess whether further study is warranted.

METHODS

We performed a case review of the three pituitary patients we have treated with (177)Lutetium DOTATATE in our institution (two atypical adenomas, one carcinoma) and dosimetric analysis of the radiation uptake in one patient.

RESULTS

Treatment was well tolerated. One patient with slowly progressive pituitary carcinoma has stable disease 40 months after completing the planned 4 cycles of treatment. Two patients with rapidly progressive atypical adenomas terminated treatment early due to continued disease progression. Dosimetric evaluation revealed inhomogenous uptake across the tumour (1.3-11.9 Gy with one cycle).

CONCLUSION

We have found mixed results in our first 3 patients with stable disease achieved only in the patient with the more slowly progressive tumour. As only a limited number of centres offer Peptide receptor radionuclide therapy, a formal study with prospective data collection may be feasible and if carried out should include dosimetric evaluation of absorbed dose.