Mixed epithelial endocrine neoplasms of the colon and rectum–An evolution over time:A systematic review

BACKGROUND Mixed tumors of the colon and rectum,composed of a combination of epithelial and endocrine elements of benign and malignant potential are rare neoplasms.These can occur anywhere in the gastrointestinal tract and are often diagnosed incidentally.Though they have been a well-documented entity in the pancreas,where the exocrine-endocrine mixed tumors have been known for a while,recognition and accurate diagnosis of these tumors in the colon and rectum,to date,remains a challenge.This is further compounded by the different terminologies that have been attributed to these lesions over the years adding to increased confusion and misclassification.Therefore,dedicated literature reviews of these lesions in the colon and rectum are inconsistent and are predominantly limited to case reports and case series of limited case numbers.Though,most of these tumors are high grade and of advanced stage,intermediate and low grade lesions of these mixed tumors are also increasingly been reported.There are no established independent consensus based guidelines for the therapeutic patient management of these unique lesions.AIM To provide a comprehensive targeted literature review of these complex mixed tumors in the colon and rectum that chronicles the evolution over time with summarization of historical perspectives of terminology and to further our understanding regarding their pathogenesis including genomic landscape,clinicoradiological features,pathology,treatment,prognosis,the current status of the management of the primary lesions,their recurrences and metastases.METHODS A comprehensive review of the published English literature was conducted using the search engines PubMed,MEDLINE and GOOGLE scholar.The following search terms[“mixed tumors colon”OR mixed endocrine/neuroendocrine tumor/neoplasm/lesion colon OR adenocarcinoma and endocrine/neuroendocrine tumor colon OR mixed adenocarcinoma and endocrine/neuroendocrine carcinoma colon OR Amphicrine tumors OR Collision tumors]were used.Eligibility criteria were defined and all potential relevant items,including full articles and/or abstracts were independently reviewed,assessed and agreed upon items were selected for in-depth analysis.RESULTS In total 237 full articles/abstracts documents were considered for eligibility of which 45 articles were illegible resulting in a total of 192 articles that were assessed for eligibility of which 139 have been selected for reference in this current review.This seminal manuscript is a one stop article that provides a detailed outlook on the evolution over time with summarization of historical perspectives,nomenclature,clinicoradiological features,pathology,treatment,prognosis and the current status of the management of both the primary lesions,their recurrences and metastases.Gaps in knowledge have also been identified and discussed.An important outcome of this manuscript is the justified proposal for a new,simple,clinically relevant,non-ambiguous terminology for these lesions to be referred to as mixed epithelial endocrine neoplasms(MEENs).CONCLUSION MEEN of the colon and rectum are poorly understood rare entities that encompass an extensive range of heterogeneous tumors with a wide variety of combinations leading to tumors of high,intermediate or low grade malignant potential.This proposed new revised terminology of MEEN will solve the biggest hurdle of confusion and misclassification that plagues these rare unique colorectal neoplasms thus facilitating the future design of multi institutional prospective randomized controlled clinical trials to develop and evaluate newer therapeutic strategies that are recommended for continued improved understanding and personal optimization of clinical management of these unique colorectal neoplasms.

Gastrointestinal Stromal Tumors in the 21^stCentury

Gastrointestinal stromal tumours (GISTs) are rare mesenchymal lesions accounting for only 0.2% of all gastrointestinal neoplasms. These tumors arise from the interstitial cells of Cajal, with mutations described in proto-oncogenes such as KIT, PDGFRA, DOG-1, and SDH. The majority of these lesions are asymptomatic, thus the true incidence remains unknown. While patients typically undergo initial endoscopy, CT scan and/or MRI, findings are often nonspecific and require a biopsy to identify the tumor. As such, immunohistochemical evaluation is the gold-standard for the accurate diagnosis of GIST. Though surgical excision remains the gold-standard for curative management, the discovery of imatinib, a tyrosine kinase inhibitor (TKI), has revolutionized the treatment of GIST in the 21st?century as a “prototype” of molecular targeted therapy for solid tumors. Risk assessment for recurrence divides these tumors into low and high-risk categories. In the latter, a role for adjuvant therapy with TKI confers a significantly better prognosis than previously observed. However, secondary mutations conferring drug resistance remain an ongoing challenge for management, as few alternative treatment options are available for patients intolerant/refractory to TKI therapy. In this review, we summarize the epidemiology, molecular pathogenesis, clinical presentation, diagnosis, pathology features, management options, and prognostic features of GISTs.

HER2-Specific Vaccines for HER2-Positive Breast Cancer Immunotherapy

Anti-human epidermal growth factor receptor-2 (HER2) immunization can be elicited by vaccination with DNA encoding the extra- or intra-cellular domain (ECD or ICD) of HER2, naked or encap-sulated in viral vectors. HER2-peptides derived from ECD or ICD of HER2, and HER2-pulsed dendritic cells (DCs) or engineered DCs expressing HER2, respectively. We performed a computer- based literature search which includes but is not limited to the following keywords: breast cancer, immunotherapy, HER2-peptide vaccine, HER2-DNA vaccine, HER-DC vaccine, HER2 vaccine, and HER2/neu, in PubMed, Medline, EMBO and Google Scholar;data from recently reported clinical trials were also included. Drawing upon this synthesis of literature, this work summarizes the de-velopment and current trend in experimental and clinical investigations in HER2-positive breast cancer using HER2-specific vaccine and immunotherapy, focusing especially on: (i) DNA-;(ii) peptide-;and (iii) DC-based vaccines. It addresses interventions that have been applied to overcome immunotolerance thereby to improve treatment outcomes. These include blocking the inhibitory cytotoxic T lymphocyte-associated protein-4 (CTLA-4), which is expressed at high levels by regulatory T (Treg) cells, or complete Treg depletion to improve T-cell activation. Moreover, modulatory interventions can provide further improvement in the efficacy of HER2-specific vaccine. The interventions include the use of immunogenic adjuvants such as cytokines interleukin-12 (IL-12), tumor necrosis factor (TNF)-α and granulocyte-macrophage colony-stimulating factor (GM-CSF), the use of Toll-like receptor (TLR) ligands and tetanus toxin’s universal epitopes such as the CD4+ help T (Th)-epitope P30, and the use of either chimeric or heterogenous xenogeneic HER2. Combining active HER2-vaccination with adoptive trastuzumab antibody immunotherapy is likely to increase the effectiveness of each approach alone. The development of effective HER2-vaccines for breast cancer remains a critical challenge. Though these novel interventions seem promising, further investigation is still needed since the results are preliminary. Furthermore, the review discusses the challenges and future perspectives in HER2-vaccine research and development.

Recent Advances in the Management of Stage IV Colon Cancer

Colon cancer is the second commonest cause of cancer-related death in Canadian men and women, with approximately one-third of patients dying from this disease. One quarter of patients present with metastases initially, and up to half of all colon cancer patients will develop stage IV disease over the course of their life. Despite ongoing advances in the evolution of newer cytotoxic drugs, targeted biological agents and improved metastasectomy techniques, the gain in overall survival in these patients is of low magnitude. This manuscript is a targeted review of the recent advances over the last decade in the management of advanced stage IV colon cancer as available in the published English literature. The two major arms of metastatic colon cancer management that include surgery and systemic chemotherapy and palliative measures as available are discussed. A multi-modality team-based approach involving medical oncologists, surgical oncologists, radiologists, and other health-care providers continues to be critical for ongoing success in the therapeutic management of these patients. Future studies of well-designed prospective, randomized-controlled clinical trials to develop and evaluate newer therapeutic strategies are recommended for continued and improved understanding for optimization of clinical management in advanced colon cancer.

Pancreatic Neuroendocrine Tumors in the 21^stCentury—An Update

Pancreatic neuroendocrine tumors (PNETs) are rare, reported to account for less than 1% - 2% of all pancreatic tumors. This, however, is likely an underestimation, as improved radiologic techniques and heightened awareness have resulted in an increase in the detection of incidentalomas, with estimations of true prevalence as high as 10%. The term “PNET” is an umbrella name that encompasses a heterogeneous group of neoplasms each with distinct clinical presentations, diagnostic radiographic features, management principles, and tumor/patient outcomes. In this context, accurate diagnosis is challenging, and management guidelines remain unclear. A high degree of clinical suspicion is required for best patient management. This manuscript provides an update on PNETs in the 21st century, in which we re-examine the terminology, epidemiology, classification, etiopathogenesis, radiographic and histopathologic diagnostic features, management for localized and metastatic disease, as well as a review of features defining functional and non-functional PNETS, and finally deliberates on the prognosis and predictive features of this unpredictable and largely unfathomable neoplasm.

Distinct roles but cooperative effect of TLR3/9 agonists and PD-1 blockade in converting the immunotolerant microenvironment of irreversible electroporation-ablated tumors

Irreversible electroporation(IRE)is a new cancer ablation technology,but methods to improve IRE-induced therapeutic immunity are only beginning to be investigated.We developed a mouse model bearing large primary(300 mm^(3))and medium distant(100 mm^(3))EG7 lymphomas engineered to express ovalbumin(OVA)as a nominal tumor antigen.We established experimental protocols including IRE alone and IRE combined with Toll-like receptor(TLR)3/9 agonists(poly I:C/CpG)(IRE+pIC/CpG),PD-1 blockade(IRE+PD-1 blockade),or both(IRE+Combo)to investigate therapeutic effects on primary and distant EG7 tumors and conversion-promoting effects on the immunotolerant tumor microenvironment(TME).We demonstrated that IRE alone simulated very weak OVA-specific CD8^(+)T cell responses and did not inhibit primary tumor growth.IRE+pIC/CpG synergistically stimulated more efficient OVA-specific CD8^(+)T cell responses and primary tumor growth inhibition than IRE+PD-1 blockade.IRE+pIC/CpG played a major role in the modulation of immune cell profiles but a minor role in the downregulation of PD-L1 expression in the TME and vice versa for IRE+PD-1 blockade.IRE+Combo cooperatively induced potent OVA-specific CD8^(+)T cell immunity and rescued exhausted intratumoral CD8^(+)T cells,leading to eradication of not only primary tumors but also untreated concomitant distant tumors and lung metastases.IRE+Combo efficiently modulated immune cell profiles,as evidenced by reductions in immunotolerant type-2(M2)macrophages,myeloid-derived suppressor-cells,plasmacytoid dendritic cells,and regulatory T cells and by increases in immunogenic M1 macrophages,CD169^(+)macrophages,type-1 conventional dendritic cells,and CD8^(+)T cells,leading to conversion of immunotolerance in not only primary TMEs but also untreated distant TMEs.IRE+Combo also showed effective therapeutic effects in two breast cancer models.Therefore,our results suggest that IRE+Combo is a promising strategy to improve IRE ablation therapy in cancer.