Purpose: The natural history and prognosis of appendiceal adenocarcinomas differ from those of adenocarcinomas arising in other large bowel sites. We aimed to compare the molecular profiles exhibited by appendiceal adenocarcinomas and colorectal cancers, or between the histopathologic subtypes of appendiceal adenocarcinoma.Experimental Design: A total of 183 samples from appendiceal adenocarcinoma [46 adenocarcinoma, not otherwise specified (NOS), 66 pseudomyxoma peritonei (PMP), 44 mucinous adenocarcinoma (MU), and 27 signet ring cell carcinoma (SR)], 994 from right-sided colorectal cancer (R-CRC), and 1,080 from left-sided CRC (L-CRC) were analyzed by next-generation sequencing (NGS) and IHC markers. Microsatellite instability (MSI) and tumor mutational burden (TMB) were tested by NGS, and programmed death ligand 1 (PD-L1) by IHC.Results: We observed high mutation rates in appendiceal adenocarcinoma samples for KRAS (55%), TP53 (40%), GNAS (31%), SMAD4 (16%), and APC (10%). Appendiceal adenocarcinoma exhibited higher mutation rates in KRAS and GNAS, and lower mutation rates in TP53, APC, and PIK3CA (6%) than colorectal cancers. PMP exhibited much higher mutation rates in KRAS (74%) and GNAS (63%), and much lower mutation rates in TP53 (23%), APC (2%), and PIK3CA (2%) than NOS. Alterations associated with immune checkpoint inhibitor response (MSI-high, TMB-high, PD-L1 expression) showed similar frequency in appendiceal adenocarcinoma compared with L-CRC, but not R-CRC, and those of NOS were higher than other subtypes of appendiceal adenocarcinoma and L-CRC.Conclusions: Molecular profiling of appendiceal adenocarcinoma revealed different molecular characteristics than noted in R-CRC and L-CRC, and molecular heterogeneity among the histopathologic subtypes of appendiceal adenocarcinoma. Our findings may be critical to developing an individualized approach to appendiceal adenocarcinoma treatment.P value was based on Fisher exact test. Blanks are P > 0.05. b P < 0.05 compared with appendiceal adenocarcinoma. Analysis and interpretation of data (e.g., statistical analysis, biostatistics, computational analysis):

Background The use of non-autologous stem cells isolated from healthy donors for stem cell therapy is an attractive approach since the stem cells can be culture expanded in advance, thoroughly tested, and formulated into off-the-shelf medicine. However, HLA compatibility and related immunosuppressive protocols can compromise therapeutic efficacy and cause unwanted side effects. Methods Mesenchymal stem cells (MSCs) have been postulated to possess unique immune regulatory function. We explored the immunomodulatory property of human and porcine MSCs for the treatment of δ-sarcoglycan-deficient dystrophic hamster muscle without immunosuppression. Circulating as well as tissue markers of inflammation were analyzed. Muscle regeneration and stem cell fate were characterized. Results Total white blood cell counts and leukocyte distribution profiles were similar among the saline- and MSC-injected dystrophic hamsters one month post treatment. Circulating levels of immunoglobulin A, vascular cell adhesion molecule-1, myeloperoxidase, and major cytokines involved in inflammatory response were not elevated by MSCs, nor were expression of the leukocyte common antigen CD45 and the cytokine transcriptional activator NF-κB in the injected muscle. Treated muscles exhibited increased cell cycle activity and attenuated oxidative stress. Injected MSCs were found to be trapped in the musculature, and contribute to both preexisting and new muscle fibers, and mediates capillary formation. Conclusions Intramuscular injection of non-autologous MSCs can be safely used for the treatment of dystrophic muscle in immunocompetent hosts without inflaming the host immune system.

Aim:To compare PD-L1 expression between metastatic uveal melanoma (MUM) and metastatic cutaneous melanoma (MCM). Materials & methods: A total of 295 MCM and 78 MUM specimens were analyzed for tumor cell PD-L1 expression. Additionally, 91 MCM and 45 MUM specimens were analyzed for PD-1 expression on tumor-infiltrating lymphocytes. Results: A total of 77/295 (26.1%) MCM specimens expressed PD-L1 as compared to 4/78 (5.1%) MUM specimens (p < 0.0001). PD-1 expression on tumor-infiltrating lymphocytes was greater in MCM (73.6%; 67/91) than in MUM (51.1%; 23/45), respectively (p = 0.009). Conclusion: Significant differences exist in PD-L1 expression between MCM and MUM. The lower PD-L1 expression in MUM may provide a rationale for failure of PD-1 inhibitor therapy and suggests that immune evasion in this disease may occur via alternative mechanisms. Uveal melanoma originates from melanocytes in the choroid, ciliary body and iris of the eye [1]. It is the most common primary intraocular malignancy in adults and occurs almost exclusively in Caucasians, with an incidence of approximately 5-7/million/year in certain European populations [2]. In the USA, it represents about 5% of all melanoma diagnoses [1,3]. Uveal melanoma tends to recur in approximately 50% of the cases despite successful therapy of the primary tumor, in particular those whose tumors have certain risk factors for metastasis, such as large tumor size, ciliary body location, epithelioid cell morphology, high mitotic count and chromosomal abnormalities (e.g., chromosome 3 loss, 8q gain) [4]. Compared with cutaneous melanoma, uveal melanoma is characterized by its distinct genetic profile and clinical presentation, where most metastases are detected in the liver [5][6][7][8][9][10]. Once uveal melanoma metastasizes, prognosis is poor because metastatic uveal melanoma (MUM) tends to be widespread within the liver and only surgically resectable in some cases [11,12]. Therefore, there is an unmet need for investigating effective systemic therapies.Systemic immunotherapy with checkpoint inhibitors has vastly improved the treatment of metastatic cutaneous melanoma (MCM), leading to long-term durable responses [13,14]. MUM patients are often treated with immune checkpoint inhibitors identical to those used in the treatment of MCM (anti-programmed death-1 [PD-1] and anti-CTLA4 [Cytotoxic T-lymphocyte-associated protein 4] antibodies), either as monotherapy or in combination. Contrary to MCM, MUM demonstrates a poor response to these immune checkpoint blockades [15] (Table 1) [16][17][18][19][20][21][22][23] One of the mechanisms by which tumors evade the immune system is through upregulation and expression of PD-L1 protein on their surface. PD-L1 on tumor cells interacts with PD-1 receptor expressed on activated T cells, leading to T-cell exhaustion, anergy and ultimately, immune response abandonment [24,25]. Inhibition of the PD-1/PD-L1 interaction is the mechanism by which anti-PD-1 antibodies induce T-cell activation and antitumor effect.We evaluated the express...

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Goblet cell carcinoid (GCC) is a distinct subtype of appendiceal neoplasm that exhibits unique clinical and pathologic features. We aimed to reveal the molecular profiles of GCC compared with other appendiceal tumors, such as adenocarcinomas and neuroendocrine tumors. A total of 495 appendiceal tumor samples (53 GCCs, 428 adenocarcinomas, and 14 neuroendocrine tumors) were tested with next-generation sequencing (NGS) on a 592-gene panel and IHC. Microsatellite instability (MSI)/mismatch repair (MMR) status was tested with a combination of NGS, IHC, and fragment analyses. Tumor mutational burden (TMB) was evaluated by NGS, and PD-L1 expression was tested by IHC (SP142). The most prevalent mutated genes within GCCs were TP53 (24.0%), ARID1A (15.4%), SMAD4 (9.4%), and KRAS (7.5%). Pathway-specific alterations were dominantly observed in cell cycle, MAPK, epigenetic, and TGFβ signaling pathways. GCCs as compared with adenocarcinomas exhibited significantly lower mutation rates in KRAS, GNAS, and APC, and significantly higher mutation rates in CDH1, CHEK2, CDC73, ERCC2, and FGFR2. GCCs as compared with neuroendocrine tumors showed significantly lower mutation rates in KRAS, APC, BRCA2, and FANCA. In GCCs, MSI high/MMR deficient, TMB high (≥17 mutations/Mb), and PD-L1 expression were seen in 0.0%, 0.0%, and 2.0% of tumors, respectively. No significant differences were observed in any immunotherapy-related markers examined when compared with adenocarcinomas and neuroendocrine tumors. In conclusion, GCCs had considerably distinct mutational profiles compared with appendiceal adenocarcinomas and neuroendocrine tumors. Understanding these molecular characteristics may be critical for the development of novel and more effective treatment strategies for GCC.

231 Background: Goblet cell carcinoid (GCC) is a distinct subtype of appendiceal neoplasm that exhibits unique clinical and pathologic features. There are a few reports focusing on the molecular differences between GCC and other appendiceal tumors such as adenocarcinoma and neuroendocrine tumor (NET). Methods: A total of 495 appendiceal tumor samples (53 GCCs, 428 adenocarcinomas and 14 NETs) were tested with Next-Generation Sequencing (NGS) on a 592-gene panel and immunohistochemistry (IHC). Microsatellite instability (MSI) / mismatch repair (MMR) status was tested with a combination of NGS, IHC and fragment analysis. Tumor mutational burden (TMB) was evaluated by NGS, and PD-L1 were tested by IHC (SP142). Molecular characteristics of GCCs are compared with those of adenocarcinomas and NETs, using Chi-square test. Results: The top five genes with most frequent mutation rate in GCCs were TP53 (24.0%), ARID1A (15.4%), SMAD4 (9.4%), KRAS (7.5%) and CHEK2 (4.0%). Compared to adenocarcinomas, GCCs showed significantly lower mutation rates in KRAS (7.5% vs 60.4%), GNAS (3.8% vs 34.4%), APC (1.9% vs 11.7%), while significantly higher mutation rates in CDH1 (3.8% vs 0.7%), CHEK2 (4.0% vs 0.3%), CDC73 (2.0% vs 0.0%), ERCC2 (2.0% vs 0.0%) and FGFR2 (1.9% vs 0.0%). Compared to NETs, GCCs showed significantly lower mutation rate in KRAS (7.5% vs 28.6%), APC (1.9% vs 28.6%), BRCA2 (0.0% vs 7.1%) and FANCA (0.0% vs 7.1%), with all p < 0.05. In GCCs, MSI-H/dMMR, TML-high (> 17mut/Mb) and PD-L1 expression were seen in 0.0%, 0.0% and 2.0%, respectively. No significant difference was observed in these immune-related markers’ frequency, compared to adenocarcinomas and NETs. Conclusions: GCCs had considerably distinct mutational profile compared to appendiceal adenocarcinomas and NETs. Understanding these molecular characteristics may be critical for a development of effective treatment strategy in GCC.