Radiotherapy with concurrent temozolomide for the management of extraneural metastases in pituitary carcinoma

Recent Therapeutic Advances in Pituitary Carcinoma

Pituitary carcinoma (PC) is a rare, aggressive malignancy that comprises 0.1-0.2% of all pituitary tumors. PC is defined anatomically as a pituitary tumor that metastasizes outside the primary intrasellar location as noncontiguous lesions in the central nervous system or as metastases to other organs. Similar to pituitary adenoma, PC originates from various cell types of the pituitary gland and can be functioning or nonfunctioning, with the former constituting the majority of the cases. Compression of intricate skull-based structures, excessive hormonal secretion, impaired pituitary function from therapy, and systemic metastases lead to debilitating symptoms and a poor survival outcome in most cases. PC frequently recurs despite multimodality treatments, including surgical resection, radiotherapy, and biochemical and cytotoxic treatments. There is an unmet need to better understand the pathogenesis and molecular characterization of PC to improve therapeutic strategies. As our understanding of the role of signaling pathways in the tumorigenesis of and malignant transformation of PC evolves, efforts have focused on targeted therapy. In addition, recent advances in the use of immune checkpoint inhibitors to treat various solid cancers have led to an interest in exploring the role of immunotherapy for the treatment of aggressive refractory pituitary tumors. Here, we review our current understanding of the pathogenesis, molecular characterization, and treatment of PC. Particular attention is given to emerging treatment options, including targeted therapy, immunotherapy, and peptide receptor radionuclide therapy.

Delayed Craniospinal Metastasis of Aggressive Nonfunctioning Pituitary Adenomas as Pituitary Carcinomas

Background Clinical behavior of pituitary neoplasms is peculiar and notoriously difficult to predict. While aggressive tumors are common, metastasis is very rare, can be highly delayed, and there are no histological or clinical features to meaningfully predict this happening. Endocrinologically silent tumors are particularly difficult, as there is less opportunity to detect early metastasis. Together, this amounts to a situation of uncertainty over the appropriate management of such tumors before and after metastasis.

Case Description The authors report two cases of nonfunctioning aggressive pituitary adenoma (APA) each requiring two transsphenoidal surgeries, a transcranial resection and radiotherapy. Both these tumors subsequently metastasized caudally along the neuraxis, years later, as a null cell carcinoma associated with a germline CHEK2 mutation and a silent Crooke's cell carcinoma. The former represents a novel oncogenetic association.

Conclusion Delayed drop dural metastasis of pituitary carcinoma is becoming increasingly recognized. Surgical resection of the distant disease to confirm the diagnosis and relieve the mass effect, followed by temozolomide chemotherapy, is the current treatment of choice. The need for both long-term follow-up in patients with APA, and a high degree of suspicion toward dural-based radiographic findings is emphasized.

Case Report: Progression of a Silent Corticotroph Tumor to an Aggressive Secreting Corticotroph Tumor, Treated by Temozolomide. Changes in the Clinic, the Pathology, and the β-Catenin and α-SMA Expression

Clinically silent corticotroph tumors are usually macroadenomas that comprise 20% of ACTH tumors. They frequently progress to aggressive tumors with high recurrence, invasiveness, and on rare occasions, they may become hormonally active causing Cushing's disease. Trustable biomarkers that can predict their aggressive course, as well as their response to traditional or new therapies, are paramount. Aberrant β-Catenin expression and localization have been proposed as responsible for several malignancies including pituitary tumors. Nevertheless, the role of β-Catenin in the aggressive transformation of silent corticotropinomas and their response to Temozolomide salvage treatment have not been explored yet. In this work, we present a case of a silent corticotroph tumor that invaded cavernous sinus and compressed optic chiasm and, after a first total resection and tumor remission it recurred six years later as an aggressive ACTH-secreting tumor. This lesion grew with carotid compromise and caused Cushing's signs. It required multiple medical treatments including Cabergoline, Ketoconazole, TMZ, and radiotherapy. Besides, other two surgeries were needed until it could be controlled. Interestingly, we found α-SMA vascular area reduction and differential β-Catenin cell localization in the more aggressive tumor stages characterized by high Ki-67 indexes and p53 expression. Our results may indicate a role of angiogenesis and β-Catenin trigged events in the pituitary tumor progression, which could in turn affect the response to TMZ and/or conventional treatments. These molecular findings in this unusual case could be useful for future management of aggressive pituitary tumors.

Incidence, demographics, and survival of patients with primary pituitary tumors: a SEER database study in 2004-2016

Comprehensive investigations on the incidence and prognosis of pituitary tumors are still lacking. The present study aims to summarize the incidence, demographics, and survival outcome of pituitary adenoma on a population-based level. This study includes all pituitary adenomas reported in the Surveillance, Epidemiology, and End Results (SEER) database from 2004 to 2016 in the United States. Extensive clinical and demographic characteristics were extracted and submitted to group comparisons. The standardized incidence rate was calculated and stratified by year at diagnosis, age/sex and age/treatment groups. The Kaplan–Meier analysis and multivariable regressions were performed to identify the factors associated with overall survival. A total of 47,180 pituitary tumors were identified, including 47,030 typical adenomas, 111 uncertain behavior pituitary adenomas, and 39 pituitary carcinomas. The overall standardized incidence rate was 4.8 cases per 100,000 person-years and the annual incidence rate continually trended upwards, with a peak seen in 2015. We noticed a bimodal age-related distribution in females and a unimodal distribution in males. In the multivariate regression analysis, the factors associated with prolonged survival included typical adenoma, younger age, and smaller tumor size. Whereas, black and male patients had worse overall survival. Our study provides a reliable estimate on the incidence of pituitary adenoma and confirms that the annual standardized incidence rate is increasing. Pituitary adenomas have a satisfactory long-term prognosis and age, tumor size, and tumor subtypes are related to overall survival. Though statistically significant, our inferential findings should be constrained within the limitations of SEER database.

Diagnosis and treatment of refractory pituitary adenomas: a narrative review

Although aggressive pituitary adenomas (PAs) have been proposed and widely discussed for more than a decade, there is no general agreement regarding their definition, diagnosis or management. As one of the largest pituitary centers in China, we have diagnosed and treated more than fifty cases of aggressive PA and 3 pituitary carcinomas in the past 5 years and proposed a new term, i.e., refractory PAs, to define these adenomas. The definitions of aggressive and refractory PAs overlap with each other, though there are some differences between them. We interpret the definition for refractory PA in this review, emphasizing that more attention and early identification of these adenomas are needed. Although temozolomide (TMZ) has been used to treat pituitary carcinomas and refractory PA since 2006, which has significantly improved the prognosis of these patients, treatment of refractory PA is a tremendous challenge for endocrinologists and neurosurgeons. Overall, refractory PA is defined as PA with a Ki-67 labeling index ≥3%, a faster growth rate than that of normal PA, infiltration of surrounding tissues, recurrence or regrowth in the early postoperative period, and continued growth and/or secretion of excessive hormones despite attempts to control it. These criteria for refractory PA are stricter than for aggressive PA. The diagnosis and treatment of refractory PA requires the collaboration of a multidisciplinary team to achieve the best results.

Temozolomide therapy for aggressive pituitary tumours - current understanding and future perspectives

The use of temozolomide (TMZ) for the management of aggressive pituitary tumours (APT) has revolutionised clinical practice in this field with significantly improved clinical outcomes and long-term survival. Its use is now well established however a large number of patients do not respond to treatment and recurrence after cessation of TMZ is common. A number of challenges remain for clinicians such as appropriate patient selection, treatment duration and the role of combination therapy. This review will examine the use of TMZ to treat APT including mechanism of action, treatment regimen and duration; biomarkers predicting response to treatment and patient selection; and current evidence for administration of TMZ in combination with other agents.

Pituitary carcinoma: Two case reports and review of literature

BACKGROUND

Pituitary carcinoma is a rare type of malignancy that can be very difficult to diagnose and treat. Many cases were diagnosed at autopsy. Delays in diagnosis often adversely impact patients' outcomes. Even with prompt diagnosis, treatment decisions remain challenging in the absence of randomized controlled trials.

CASE SUMMARY

We report two cases of pituitary carcinoma in men with a history of pituitary adenoma. In the first case, a 55-year-old man was initially diagnosed with pituitary macroadenoma. He underwent subtotal debulking of the tumor followed by adjuvant radiotherapy. Subsequently, he developed relapsed disease and multifocal intracranial metastases and a diagnosis of pituitary carcinoma was rendered. He passed away despite several lines of systemic therapies including temozolomide, lomustine and bevacizumab. Another 52-year-old man was diagnosed with atypical pituitary adenoma with presentation of sudden onset of vision loss in the right eye. He had recurrent pituitary carcinoma with spinal metastases, treated with surgery, radiation and temozolomide.

CONCLUSION

Pituitary carcinoma is a rare neoplasm with poor prognosis that is difficult to diagnose and treat. The small number of cases restricts our ability to design randomized clinical trials. Management is largely driven by retrospective studies and case series. Establishing molecular biomarkers and comprehensive genomic profiling could help in decisions about diagnosis and management of pituitary carcinoma.

Multimodal therapy in aggressive pituitary tumors

The concept of aggressive pituitary tumor (APT) has been precisely defined in recent years. These tumors are characterized by morphological (radiological or histopathological) data of invasion, proliferative activity superior to that of typical adenomas and a clinical behavior characterized by resistance to standard therapies and frequent recurrences. The absence of cerebrospinal or distant metastases differentiates them from the pituitary carcinoma. APTs account for about 10% of all pituitary neoplasm. Proper diagnostic implies participation not only of radiological and hormonal investigation but also a thorough pathological assessment including proliferation markers and immunohistochemistry for hormones and transcription factors. Surgical resection, aiming gross total resection or tumor debulking, is the mainstay initial therapy in most patients. Most patients with APTs need more than one surgical intervention, pituitary radiation, sometimes on more than one occasion, and multiple sequential or combined medical treatments, to finally be doomed to unusual treatments, such as alkylating agents (temozolomide alone or in combination), molecular targeted therapies, or peptide receptor radionuclide therapy. Multimodal therapy, implemented by experts, preferably in specialized centers with high volume caseload, is the only way to improve the prognosis of patients with these uncommon tumors. The research needs in this area are multiple and include a greater knowledge of the molecular biology of these tumors, establishment of protocols for monitoring and sequencing of treatments, development of multicenter studies and international registries.

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.

Detection of circulating tumor cells in patients with pituitary tumors

BACKGROUND

Circulating tumor cells (CTCs) are tumor cells that have shed from a primary tumor and circulate in the peripheral blood. Recent experimental and clinical studies show that CTCs can be detected in early-stage disease.

CASE PRESENTATION

We report three cases of pituitary adenoma (PA) in which tumor cells with particles were detected in the interstitial vascular compartment by transmission electron microscopy. Tumors were completely resected. Immunohistochemical analysis showed a β-catenin score of 10.5 ± 1.5 in the three cases with CTCs compared with 2.4 ± 0.5 in 24 control adenomas. The Ki-67 labeling index was 2.1 ± 0.7 in CTCs vs. 0.2 ± 0.3 in control cases (p = 0.043), and the p53 score was 4.33 ± 1.3 vs. 0.31 ± 0.17 (p = 0.000). The E-cadherin score did not differ significantly between the two groups.

CONCLUSIONS

CTCs can be detected in benign tumors such as PAs and not only in late-stage malignant tumors with apparent distant metastases. The present findings suggest that pituitary carcinomas develop from adenomas.

Treatment of aggressive pituitary tumours and carcinomas: results of a European Society of Endocrinology (ESE) survey 2016

OBJECTIVE

To collect outcome data in a large cohort of patients with aggressive pituitary tumours (APT)/carcinomas (PC) and specifically report effects of temozolomide (TMZ) treatment.

DESIGN

Electronic survey to ESE members Dec 2015-Nov 2016.

RESULTS

Reports on 166 patients (40 PC, 125 APT, 1 unclassified) were obtained. Median age at diagnosis was 43 (range 4-79) years. 69% of the tumours were clinically functioning, and the most frequent immunohistochemical subtype were corticotroph tumours (45%). Ki-67 index did not distinguish APT from PC, median 7% and 10% respectively. TMZ was first-line chemotherapy in 157 patients. At the end of the treatment (median 9 cycles), radiological evaluation showed complete response (CR) in 6%, partial response (PR) in 31%, stable disease (SD) in 33% and progressive disease in 30%. Response was more frequent in patients receiving concomitant radiotherapy and TMZ. CR was seen only in patients with low MGMT expression. Clinically functioning tumours were more likely to respond than non-functioning tumours, independent of MGMT status. Of patients with CR, PR and SD, 25, 40 and 48% respectively progressed after a median of 12-month follow-up. Other oncological drugs given as primary treatment and to TMZ failures resulted in PR in 20%.

CONCLUSION

This survey confirms that TMZ is established as first-line chemotherapeutic treatment of APT/PC. Clinically functioning tumours, low MGMT and concurrent radiotherapy were associated with a better response. The limited long-term effect of TMZ and the poor efficacy of other drugs highlight the need to identify additional effective therapies.

European Society of Endocrinology Clinical Practice Guidelines for the management of aggressive pituitary tumours and carcinomas

BACKGROUND

Pituitary tumours are common and easily treated by surgery or medical treatment in most cases. However, a small subset of pituitary tumours does not respond to standard medical treatment and presents with multiple local recurrences (aggressive pituitary tumours) and in rare occasion with metastases (pituitary carcinoma). The present European Society of Endocrinology (ESE) guideline aims to provide clinical guidance on diagnosis, treatment and follow-up in aggressive pituitary tumours and carcinomas.

METHODS

We decided upfront, while acknowledging that literature on aggressive pituitary tumours and carcinomas is scarce, to systematically review the literature according to the GRADE (Grading of Recommendations Assessment, Development and Evaluation) system. The review focused primarily on first- and second-line treatment in aggressive pituitary tumours and carcinomas. We included 14 single-arm cohort studies (total number of patients = 116) most on temozolomide treatment (n = 11 studies, total number of patients = 106). A positive treatment effect was seen in 47% (95% CI: 36-58%) of temozolomide treated. Data from the recently performed ESE survey on aggressive pituitary tumours and carcinomas (165 patients) were also used as backbone for the guideline. SELECTED RECOMMENDATION: (i) Patients with aggressive pituitary tumours should be managed by a multidisciplinary expert team. (ii) Histopathological analyses including pituitary hormones and proliferative markers are needed for correct tumour classification. (iii) Temozolomide monotherapy is the first-line chemotherapy for aggressive pituitary tumours and pituitary carcinomas after failure of standard therapies; treatment evaluation after 3 cycles allows identification of responder and non-responder patients. (iv) In patients responding to first-line temozolomide, we suggest continuing treatment for at least 6 months in total. Furthermore, the guideline offers recommendations for patients who recurred after temozolomide treatment, for those who did not respond to temozolomide and for patients with systemic metastasis.