<p>Pancreatic endocrine tumors (PETs) occur sporadically or in the familial multiple endocrine neoplasia type 1 (MEN1) syndrome, whereas midgut carcinoids are nonfamilial, malignant endocrine tumors of the intestine. For these tumor entities morphological criteria are of limited use for prognostic prediction and selection of treatment. Genetic characterization may give additional information of clinical use and reveal pathways involved in tumor development.</p><p>Molecular genetic alterations in sporadic and MEN1-associated PETs and midgut carcinoids were studied with LOH and mutational analysis. In addition, immunohistochemistry was used to clarify gene expression. Detected genetic aberrations were correlated to the disease course of individual patients.</p><p>Somatic mutations of the<i> MEN1</i> gene at chromosome <i>11q13</i> were detected in 1/3 of sporadic PETs<i>. </i>Moreover, LOH was found in 70% of the lesions. All tumors with somatic <i>MEN1</i> mutations displayed loss of the remaining allele showing that the <i>MEN1</i> gene is involved in development of sporadic PETs.</p><p> Sporadic and MEN1 PETs were analyzed for LOH at <i>3p,</i> <i>11q13</i> and <i>18q</i>. A relation of LOH at <i>11q13</i> and <i>3p</i> to malignancy was found for the sporadic tumors. None of the benign tumors (all of them insulinomas) had allelic loss at <i>3p</i> or <i>11q13</i>, versus 92 % (p<0.01) of the malignant tumors (including malignant insulinomas). 1/4 of both sporadic and MEN1 lesions displayed LOH at <i>18q</i>, without altered <i>Smad4/DPC4</i>.</p><p>Genome-wide LOH screening of MEN1 PETs revealed multiple allelic deletions without general correlation to tumor size or malignancy. All tumors displayed LOH at the <i>MEN1 </i>locus, and 30% on chromosomes 3, 6, 8, 10, 18 and 21. Intratumoral heterogeneity was revealed, with chromosome 6 and 11 deletions in most tumor cells. Chromosome 6 deletions were mainly found in lesions from patients with malignant features. </p><p>A similar genome-wide LOH screening was performed on midgut carcinoids. Deletions at chromosome <i>18q</i> were found in 88% of the tumors indicating a potential tumor suppressor locus.</p>

Pancreatic endocrine tumors (PETs) occur sporadically or in the familial multiple endocrine neoplasia type 1 (MEN1) syndrome, whereas midgut carcinoids are nonfamilial, malignant endocrine tumors of the intestine. For these tumor entities morphological criteria are of limited use for prognostic prediction and selection of treatment. Genetic characterization may give additional information of clinical use and reveal pathways involved in tumor development. Molecular genetic alterations in sporadic and MEN1-associated PETs and midgut carcinoids were studied with LOH and mutational analysis. In addition, immunohistochemistry was used to clarify gene expression. Detected genetic aberrations were correlated to the disease course of individual patients. Somatic mutations of the MEN1 gene at chromosome 11q13 were detected in 1/3 of sporadic PETs. Moreover, LOH was found in 70% of the lesions. All tumors with somatic MEN1 mutations displayed loss of the remaining allele showing that the MEN1 gene is involved in development of sporadic PETs. Sporadic and MEN1 PETs were analyzed for LOH at 3p, 11q13 and 18q. A relation of LOH at 11q13 and 3p to malignancy was found for the sporadic tumors. None of the benign tumors (all of them insulinomas) had allelic loss at 3p or 11q13, versus 92 % (p&lt;0.01) of the malignant tumors (including malignant insulinomas). 1/4 of both sporadic and MEN1 lesions displayed LOH at 18q, without altered Smad4/DPC4. Genome-wide LOH screening of MEN1 PETs revealed multiple allelic deletions without general correlation to tumor size or malignancy. All tumors displayed LOH at the MEN1 locus, and 30% on chromosomes 3, 6, 8, 10, 18 and 21. Intratumoral heterogeneity was revealed, with chromosome 6 and 11 deletions in most tumor cells. Chromosome 6 deletions were mainly found in lesions from patients with malignant features. A similar genome-wide LOH screening was performed on midgut carcinoids. Deletions at chromosome 18q were found in 88% of the tumors indicating a potential tumor suppressor locus.

<p>Midgut carcinoid tumours are rare with an incidence of 0.5-2.1/100 000. The primary tumour is usually small and grows slowly but has almost always set metastases at diagnosis. When radically operated, most patients will eventually recur in their disease. </p><p>We evaluated different methods in detecting recurrent disease in 61 malignant midgut carcinoid tumours that had been radically operated. Thirty-eight patients have been diagnosed with a recurrence. In 32/38 of these patients P-Chromogranin A was the first method to indicate a recurrence. We therefore recommend using P-CgA in the work up in these patients.</p><p>We investigated characteristics, survival and independent factors that could be of bad prognostic value. We found that in our 284 malignant midgut carcinoid tumours, 208/284 (73%) had distant metastases and 30/284 (11%) had carcinoid heart disease. Median survival was 115.5 months and five-year survival was 77%. In a multivariate analysis liver metastases and carcinoid heart disease were poor prognostic factors.</p><p>We performed a phase II study with octreotide pamoate investigating the clinical effect in 12 malignant midgut carcinoid tumours in a progressive phase. We found that 9/12 (75%) were stabilised for a median duration of 12 months. We think that this is a good effect considering the advanced stage.</p><p>We investigated the frequency of four different tyrosine kinase receptors, platelet derived growth factor receptor (PDGR) α and β, epidermal growth factor receptor (EGFR) and c-kit, in 36 malignant midgut carcinoid tumours with immunohistochemistry. We found that 13/34 (38%) tumour samples expressed PDGFRα, 29/33 (88%) PDGFRβ, 24/33 (73%) EGFR, whereas none expressed c-kit. This implicates that midgut carcinoid tumours might be susceptible to treatment with tyrosine kinase receptor inhibitors. </p>

<p>In this study, metastasizing serotonin-producing ileocaecal carcinoid tumours (MSPCs) were examined for biological characteristics that could be used to define clinically relevant subgroups within this patient population. Possible targets for new treatment options were also explored.</p><p>It was found that MSPCs share several biological characteristics such as expression of serotonin, tachykinins (TKs), chromogranin A, islet autoantigen-2 and connective tissue growth factor (CTGF). TKs and serotonin were demonstrated in the same endocrine tumours in the gut and lung. IA-2 expression was shown to be up-regulated in MSPCs, possibly in connection with active hormone secretion. CTGF expression was high in tumour areas adjacent to extensive stroma expressing alpha-smooth muscle actin. This indicated myofibroblast differentiation, which may be associated with fibrosis-related complications prevalent in patients with MSPCs. When compared with other endocrine tumours, MSPCs behaved as a relatively homogeneous group, though within the MSPC population several subgroups could be defined. Patients with tumours displaying either a solid growth pattern and/or a Ki67 index ≥1% had a less favourable prognosis than those who did not. Another group of patients, who had increased plasma TK concentrations, were more likely to suffer from severe diarrhea. This information should be considered when discussing clinical treatment and when undertaking tumour biological studies. New treatment possibilities, such as drugs that specifically target TK receptors and antibodies to CTGF, are also discussed.</p><p>In conclusion, MSPCs comprise a clinically relevant tumour group with similar biological features that are distinct from other endocrine tumours. Subgroups of patients within this patient category can be defined which may be relevant when establishing prognosis and when selecting future treatment modalities.</p>

Midgut carcinoid tumours are rare with an incidence of 0.5-2.1/100 000. The primary tumour is usually small and grows slowly but has almost always set metastases at diagnosis. When radically operated, most patients will eventually recur in their disease. We evaluated different methods in detecting recurrent disease in 61 malignant midgut carcinoid tumours that had been radically operated. Thirty-eight patients have been diagnosed with a recurrence. In 32/38 of these patients P-Chromogranin A was the first method to indicate a recurrence. We therefore recommend using P-CgA in the work up in these patients. We investigated characteristics, survival and independent factors that could be of bad prognostic value. We found that in our 284 malignant midgut carcinoid tumours, 208/284 (73%) had distant metastases and 30/284 (11%) had carcinoid heart disease. Median survival was 115.5 months and five-year survival was 77%. In a multivariate analysis liver metastases and carcinoid heart disease were poor prognostic factors. We performed a phase II study with octreotide pamoate investigating the clinical effect in 12 malignant midgut carcinoid tumours in a progressive phase. We found that 9/12 (75%) were stabilised for a median duration of 12 months. We think that this is a good effect considering the advanced stage. We investigated the frequency of four different tyrosine kinase receptors, platelet derived growth factor receptor (PDGR) α and β, epidermal growth factor receptor (EGFR) and c-kit, in 36 malignant midgut carcinoid tumours with immunohistochemistry. We found that 13/34 (38%) tumour samples expressed PDGFRα, 29/33 (88%) PDGFRβ, 24/33 (73%) EGFR, whereas none expressed c-kit. This implicates that midgut carcinoid tumours might be susceptible to treatment with tyrosine kinase receptor inhibitors.

In this study, metastasizing serotonin-producing ileocaecal carcinoid tumours (MSPCs) were examined for biological characteristics that could be used to define clinically relevant subgroups within this patient population. Possible targets for new treatment options were also explored. It was found that MSPCs share several biological characteristics such as expression of serotonin, tachykinins (TKs), chromogranin A, islet autoantigen-2 and connective tissue growth factor (CTGF). TKs and serotonin were demonstrated in the same endocrine tumours in the gut and lung. IA-2 expression was shown to be up-regulated in MSPCs, possibly in connection with active hormone secretion. CTGF expression was high in tumour areas adjacent to extensive stroma expressing alpha-smooth muscle actin. This indicated myofibroblast differentiation, which may be associated with fibrosis-related complications prevalent in patients with MSPCs. When compared with other endocrine tumours, MSPCs behaved as a relatively homogeneous group, though within the MSPC population several subgroups could be defined. Patients with tumours displaying either a solid growth pattern and/or a Ki67 index ≥1% had a less favourable prognosis than those who did not. Another group of patients, who had increased plasma TK concentrations, were more likely to suffer from severe diarrhea. This information should be considered when discussing clinical treatment and when undertaking tumour biological studies. New treatment possibilities, such as drugs that specifically target TK receptors and antibodies to CTGF, are also discussed. In conclusion, MSPCs comprise a clinically relevant tumour group with similar biological features that are distinct from other endocrine tumours. Subgroups of patients within this patient category can be defined which may be relevant when establishing prognosis and when selecting future treatment modalities.

Classical midgut carcinoids belong to neuroendocrine tumors of the gastroenteropancreatic tract (GEP-NETs) and are associated with serotonin overproduction. The term midgut is derived from the tumors’ embryological site of origin: enterochromaffin cells in the lower jejunum, ileum, caecum and the ascending colon. Despite their rather benign nature, these tumors can metastasize to mesentery and liver, putting patients at risk for the so-called carcinoid syndrome. This syndrome is characterized by flushes, diarrhoea and valvular heart disease due to the excessive serotonin secretion by tumor cells. Treatment of metastatic disease is currently ineffective and T cell immunotherapy has been suggested as a novel approach. We propose a number of midgut carcinoid-associated proteins as potential antigens for immunotherapy. Chromogranin A (CGA), tryptophan hydroxylase 1 (TPH-1), vesicular monoamine transporter 1 (VMAT-1), caudal type homeobox transcription factor 2 (CDX-2), islet autoantigen 2 (IA-2) and survivin represent interesting candidates based on their fairly restricted neuroendocrine tissue expression. In pursuit of potential antigens we identified a novel splicing variant of VMAT-1, lacking the second last exon. The variant, denoted VMAT1Δ15, encodes a differently translated C-terminal compared to the native form, is localized in the endoplasmic reticulum (ER) instead of large dense core vesicles and is unable to accumulate serotonin. We identify several immunogenic HLA-A*0201-binding peptide epitopes derived from our proposed antigens by analyzing CD8+ T cell responses in blood from midgut carcinoid patients. We demonstrate immune recognition of midgut carcinoid tumors in patients and in vitro generation of activated CD8+ T cells recognizing these peptide epitopes in blood from healthy controls. Patients also exhibit increased frequencies of circulating regulatory T cells (Tregs) with suppressive quality and patient lymphocytes display a decreased proliferative capacity compared to healthy controls. Midgut carcinoid tumors are frequently infiltrated by T cells, however always in the presence of Foxp3-expressing Tregs. Midgut carcinoid-associated antigens recognized by CD8+ T cells are of great interest for cellular therapies such as modified DC vaccines or adoptive T cell transfer. However, the systemic and local suppression of Th1 immunity must be considered and likely corrected in order to obtain clinically effective immunotherapies.