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Li Li, Heidi L. Weiss, Jing Li, Zhengyi Chen, Leslie Donato, and B. Mark Evers

Emerging data support a potential role of neurotensin (NT) in the development of obesity, obesity-associated comorbidities, and certain cancers. The association of NT with colon cancer risk has not been explicitly explored. We determined plasma levels of pro-NT, a stable NT precursor fragment, in 223 incident colon cancer patients and 223 age-, gender-, BMI-matched population controls participating in a population-based case-control study of colon cancer. On average, the cases have significantly higher levels of pro-NT than the controls (median = 205.6 pmol/L vs. 183.1 pmol/L, respectively; p = 0.02). Multivariate logistic regression models, adjusted for age, gender, BMI, family history of colorectal cancer, smoking, diabetes mellitus, alcohol, and NSAIDS use, show statistically significant risk associations: for continuous measure of pro-NT, the OR estimate was 1.30 (95% CI =1.03 – 1.64; p = 0.026) for each increment of 175 pmol/L; for dichotomized measure of pro-NT, the OR estimate was 1.75 (95% CI = 1.12 – 2.74; p = 0.025) for those in the top quartile comparing to the other participants. Our results support circulating levels of pro-NT as a novel risk biomarker for colon cancer.

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Tim J Takkenkamp, Mathilde Jalving, Frederik J H Hoogwater, and Annemiek M E Walenkamp

Immunotherapy in the form of immune checkpoint inhibitors (ICIs) has transformed the treatment landscape in numerous types of advanced cancer. However, the majority of patients do not benefit from this treatment modality. Although data are scarce, in general, patients with low-grade neuroendocrine tumours (NETs) do not benefit from treatment with ICIs in contrast to patients with neuroendocrine carcinoma, in which a small subgroup of patients may benefit. Low- and intermediate-grade NETs predominantly lack factors associated with response to ICIs treatment, like immune cell infiltration, and have an immunosuppressive tumour metabolism and microenvironment. In addition, because of its potential influence on the response to ICIs, major interest has been shown in the tryptophan-degrading enzymes indoleamine 2,3-dioxygenase (IDO) and tryptophan 2,3-dioxygenase (TDO). These enzymes work along the kynurenine pathway that deplete tryptophan in the tumour microenvironment. IDO and TDO are especially of interest in NETs since some tumours produce serotonin but the majority do not, which potentially deplete the precursor tryptophan. In this review, we summarize the current knowledge on the immune tumour microenvironment of neuroendocrine tumours and implications for treatment with immune checkpoint inhibitors. We also discuss (targetable) factors in the NET tumour microenvironment that potentially modulate the anti-cancer immune response.

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Jack Junjie Chan, Yirong Sim, Samuel Guan Wei Ow, Joline Si Jing Lim, Grace Kusumawidjaja, Qingyuan Zhuang, Ru Xin Wong, Fuh Yong Wong, Veronique Kiak Mien Tan, and Tira Jing Ying Tan

The ensuing COVID-19 pandemic poses unprecedented and daunting challenges to the routine delivery of oncological and supportive care to patients with breast cancer. Considerations include the infective risk of patients who are inherently immunosuppressed from their malignancy and therapies, long-term oncological outcomes from the treatment decisions undertaken during this extraordinary period, and diverted healthcare resources to support a coordinated whole-of-society outbreak response. In this review, we chronicle the repercussions of the COVID-19 outbreak on breast cancer management in Singapore and describe our approach to triaging and prioritising care of breast tumours. We further propose adaptations to established clinical processes and practices across the different specialties involved in breast oncology, with references to the relevant evidence base or expert consensus guidelines. These recommendations have been developed within the unique context of Singapore’s public healthcare sector. They can serve as a resource to guide breast cancer management for future contingencies in this city-state, while certain elements therein may be extrapolatable to other medical systems during this global public health emergency.

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Julie Refardt, Wouter T Zandee, Tessa Brabander, Richard A Feelders, Gaston J.h Franssen, Leo J Hofland, Emanuel Christ, Wouter W de Herder, and Johannes Hofland

Sufficient expression of somatostatin receptor (SSTR) in well-differentiated neuroendocrine tumours (NETs) is crucial for treatment with somatostatin analogues (SSAs) and peptide receptor radionuclide therapy (PRRT) using radio-labelled SSAs. Impaired prognosis has been described for SSTR-negative NET patients, however studies comparing matched SSTR-positive and -negative subjects who have not received PRRT are missing. This retrospective analysis of two prospectively maintained NET databases aimed to compare matched metastatic grade 1 or 2 SSTR-positive and –negative NET patients. SSTR-negativity was defined as having insufficient tumour uptake on diagnostic SSTR imaging. Patients that underwent PRRT were excluded. Seventy-seven SSTR-negative and 248 SSTR-positive grade 1-2 NET patients were included. Median overall survival rates were significantly lower for SSTR-negative compared to SSTR-positive NET patients (53 months versus 131 months; p<0.001). To adjust for possible confounding by age, gender, grade and site of origin, 69 SSTR-negative NET patients were propensity score matched to 69 SSTR-positive NET patients. Group characteristics were similar, with the exception of SSTR-negative patients receiving more often chemotherapy and targeted treatment. The inferior survival outcome of SSTR-negative compared to SSTR-positive NET patients persisted with a median overall survival of 38 months versus 131 months (p=0.012). This relationship upheld when correcting for the main influencing factors of having a higher grade tumour or receiving surgery in a multivariate Cox regression analysis. In conclusion, we showed that propensity score-matched SSTR-negative NET patients continue to have a worse prognosis compared to SSTR-positive NET patients despite receiving more aggressive treatment. Differences in tumour biology likely underlie this survival deficit.

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Derek Raghavan, Antoinette R Tan, E Shannon Story, Earle F Burgess, Laura Musselwhite, Edward S Kim, and Peter E Clark

Substantial management changes in endocrine-related malignancies have been required as a response to the COVID-19 pandemic, including a draconian reduction in the screening of asymptomatic subjects, delay in planned surgery and radiotherapy for primary tumors deemed to be indolent, and dose reductions and/or delays in initiation of some systemic therapies. An added key factor has been a patient-initiated delay in the presentation because of the fear of viral infection. Patterns of clinical consultation have changed, including a greater level of virtual visits, physical spacing, masking, staffing changes to ensure a COVID-free population and significant changes in patterns of family involvement. While this has occurred to improve safety from COVID-19 infection, the implications for cancer outcomes have not yet been defined. Based on prior epidemics and financial recessions, it is likely that delayed presentation and treatment of high-grade malignancy will be associated with worse cancer outcomes. Cancer patients are also at increased risk from COVID-19 infection compared to the general population. Pandemic management strategies for patients with tumors of breast, prostate, thyroid, parathyroid and adrenal gland are reviewed.

Open access

Xiyuan Zhang, Fabia de Oliveira Andrade, Hansheng Zhang, Idalia Cruz, Robert Clarke, Pankaj Gaur, Vivek Verma, and Leena Hilakivi-Clarke

Over 50% of women at a childbearing age in the United States are overweight or obese, and this can adversely affect their offspring. We studied if maternal obesity-inducing high fat diet (HFD) not only increases offspring’s mammary cancer risk but also impairs response to antiestrogen tamoxifen. Female rat offspring of HFD and control diet-fed dams, in which estrogen receptor-positive (ER+) mammary tumors were induced with the carcinogen 7,12-dimethylbenz[a]anthracene (DMBA), exhibited similar initial responses to antiestrogen tamoxifen. However, after tamoxifen therapy was completed, almost all (91%) tumors recurred in HFD offspring, compared with only 29% in control offspring. The increase in local mammary tumor recurrence in HFD offspring was linked to an increase in the markers of immunosuppression (Il17f, Tgfβ1, VEGFR2) in the tumor microenvironment (TME). Protein and mRNA levels of the major histocompatibility complex II (MHC-II), but not MHC-I, were reduced in the recurring DMBA tumors of HFD offspring. Further, infiltration of CD8+ effector T cells and granzyme B+ (GZMB+) cells were lower in their recurring tumors. To determine if maternal HFD can pre-program similar changes in the TME of allografted E0771 mammary tumors in offspring of syngeneic mice, flow cytometry analysis was performed. E0771 mammary tumor growth was significantly accelerated in the HFD offspring, and a reduction in the numbers of GZMB and non-significant reduction of interferon γ (IFNγ) secreting CD8+ T cells in the TME was seen. Thus, consumption of a HFD during pregnancy increases susceptibility of the female rat and mouse offspring to tumor immune suppression and mammary tumor growth and recurrence.

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Atsuko Kasajima and Gunter Klöppel

The bronchopulmonary (BP) and gastroenteropancreatic (GEP) organ systems harbor the majority of the neuroendocrine neoplasms (NENs) of the body, comprising 20% and 70% of all NENs, respectively. Common to both NEN groups is a classification distinguishing between well- and poorly differentiated NENs associated with distinct genetic profiles. Differences between the two groups concern the reciprocal prevalence of well and poorly differentiated neoplasms, the application of a Ki67 based grading, the variety of histological patterns, the diversity of hormone expression and associated syndromes, the variable involvement in hereditary tumor syndromes, and the pecularities of genetic changes. This review focuses on a detailed comparison of BP-NENs with GEP-NENs with the aim of highlighting and discussing the most obvious differences. Despite obvious differences, the principle therapeutical options are still the same for both NEN groups, but with further progress in genetics more targeted therapy strategies can be expected in future.

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Simona Grozinsky-Glasberg, Kate E Lines, Shani Avniel-Polak, Chas Bountra, and Rajesh V Thakker

Neuroendocrine neoplasms (NENs) occur usually as sporadic tumours; however, rarely, they may arise in the context of a hereditary syndrome, such as multiple endocrine neoplasia type 1 (MEN1), an autosomal dominant disorder characterised by the combined development of pancreatic NENs (pNENs) together with parathyroid and anterior pituitary tumours. The therapeutic decision for sporadic pNENs patients is multi-disciplinary and complex: based on the grade and stage of the tumor, various options (and their combinations) are considered, such as surgical excision (either curative or for debulking aims), biological drugs (somatostatin analogues), targeted therapies (mTOR inhibitors or tyrosine kinases (TK)/receptors inhibitors), peptide receptor radioligand therapy (PRRT), chemotherapy, and liver-directed therapies. However, treatment of MEN1-related NENs’ patients is even more challenging, as these tumours are usually multifocal with co-existing foci of heterogeneous biology and malignant potential, rendering them more resistant to the conventional therapies used in their sporadic counterparts, and therefore associated with a poorer prognosis. Moreover, clinical data using standard therapeutic options in MEN1-related NENs are scarce. Recent preclinical studies have identified potentially new targeted therapeutic options for treating MEN1-associated NENs, such as epigenetic modulators, Wnt pathway-targeting β-catenin antagonists, Ras signalling modulators, Akt/mTOR signalling modulators, novel somatostatin receptors analogues, anti-angiogenic drugs, as well as MEN1 gene replacement therapy. The present review aims to summarize these novel therapeutic opportunities for NENs developing in the context of MEN1 syndrome, with an emphasis on pancreatic NENs, as they are the most frequent ones studied in MEN1-NENs models to date; moreover, due to the recent shifting nomenclature of ‘pituitary adenomas’ to ‘pituitary neuroendocrine neoplasms’, relevant data on MEN1-pituitary tumours, when appropriate, are briefly described.

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Stéphanie Espiard, Ludivine Drougat, Nikolaos Settas, Sara Haydar, Kerstin Bathon, Edra London, Isaac Levy, Fabio R Faucz, Davide Calebiro, Jerome Bertherat, Dong Li, Michael A. Levine, and Constantine A Stratakis

Genetic variants in components of the protein kinase A (PKA) enzyme have been associated with various defects and neoplasms in the context of Carney complex (CNC) and in isolated cases, such as in primary pigmented nodular adrenocortical disease (PPNAD), cortisol-producing adrenal adenomas (CPAs), and various cancers. PRKAR1A mutations have been found in subjects with impaired cAMP-dependent signaling and skeletal defects; bone tumors also develop in both humans and mice with Prkar1a abnormalities. We studied the PRKACB gene in 148 subjects with PPNAD and related disorders, who did not have other PKA-related defects and identified two subjects with possibly pathogenic PRKACB gene variants and unusual bone and endocrine phenotypes. The first presented with bone and other abnormalities, and carried a de novo c.858_860GAA (p.K286del) variant. The second subject carried the c.899 C>T (p.T300M) variant and had a PPNAD-like phenotype. Both variants are highly conserved in the PRKACB gene. In functional studies, the p.K286del variant affected PRKACB protein stability and led to increased PKA signaling. The p.T300M variant did not affect protein stability or response to cAMP and its pathogenicity remains uncertain. We conclude that PRKACB germline variants are uncommon but may be associated with phenotypes that resemble those of other PKA-related defects. However, detailed investigation of each variant is needed as PRKACB appears to be only rarely affected in these conditions, and variants such as p.T300M maybe proven to be clinically insignificant, whereas others (such as p.K286del) are clearly pathogenic and may lead to a novel skeletal syndrome phenotype.