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Objective The effectiveness of everolimus for the management of pancreatic neuroendocrine neoplasms (PNENs), including the G3/NEC types, remains unclear. We therefore investigated the effectiveness of the drug for the management of PNENs. Methods We analyzed the progression-free survival (PFS) and overall survival (OS) associated with everolimus and factors influencing the PFS and OS. Results One hundred patients were evaluated. The PFS associated with the G1/G2 types tended to be significantly longer than that associated with the G3/NEC types (hazard ratio [HR], 0.45; p =0.005). A multivariate analysis showed that the significant factors influencing the PFS were age (65 years old; HR, 0.44; p =0.002), grade (G1/G2; HR, 0.42; p =0.006), everolimus treatment line (≤2nd; HR, 0.55; p =0.031), and presence of treatment with metformin (yes; HR, 0.29; p =0.044). The median OS was 63.8 months. In the multivariate analysis, the significant factors influencing the OS were grade (G1/G2; HR, 0.21; p0.001), volume of liver metastasis (≤25%; HR, 0.27; p0.001), everolimus treatment line (≤2nd; HR, 0.27; p0.001), and presence of primary tumor resection (yes; HR, 0.33; p =0.005). Conclusions The effectiveness of everolimus in the management of G3/NEC types and prognoses tended to be poorer than those associated with the G1/G2 types. Everolimus combined with metformin and early-line treatment with everolimus may be effective for managing advanced PNENs.

Objective Neuroendocrine neoplasms (NENs) are rare and indolent diseases, but the efficacy of treatment without surgical resection is temporary and limited. Targeted immunotherapy is an important treatment strategy in several cancers. However, the tumor and host immune reactions in the NEN microenvironment are poorly understood. Therefore, we investigated the immune checkpoint system and host immune response in pathological NEN specimens. Methods The expression of the mismatch repair proteins MSH2, MSH6, PMS2, and MLH1 was immunohistochemically detected in archival tissue samples obtained from 20 patients with gastroenteropancreatic NENs. We additionally assessed the expression of programmed death (PD)-1, PD-L1, and the tumor-infiltrating lymphocyte (TIL) markers CD8 and family of transcription factor P3 (FOXP3). Results All 20 NENs expressed the mismatch repair proteins MSH2, MSH6, PMS2, and MLH1. The PD-L1 and/or PD-1 expression in the tumor cells and/or TILs was confirmed in 75% of the cases. PD-1-, CD8-, and FOXP3-positive TILs were more frequently associated with PD-L1-positive tumors than with PD-L1 negative tumors (PD-1: 19.5 vs. 7.3, CD8: 18.1 vs. 7.1, FOXP3: 13.2 vs. 3.2, p=0.438, p=0.419, P=0.603, respectively). The number of cells positive for PD-1 tended to gradually increase in increasing grade of NENs but did not reach significance (Grade 1: 5.8, Grade 2: 10.2, NEC: 18.1, p=0.903). Conclusion NENs consistently express mismatch repair proteins but have a high expression of PD-L1 and/or PD-1 in the tumor microenvironment. NEC and PD-L1-positive NENs may be immunologically "hot" tumors, so an immunological approach may be an appropriate treatment strategy for these tumors.

Aberrant pancreas is defined as pancreatic tissue present outside of the pancreas and is often found incidentally during esophagogastroduodenoscopy. Obtaining sufficient tissue to differentiate aberrant pancreas from other subepithelial lesions is sometimes difficult. Due to the lack of a definitive diagnosis, patients often undergo unnecessary surgery. We herein report the first case of aberrant pancreas in which the concomitant use of needle-based probe confocal laser endomicroscopy and fine-needle aspiration supported the final diagnosis. Needle-based probe confocal laser endomicroscopy provides a real-time in vivo histopathology evaluation and may be a feasible means of diagnosing aberrant pancreas.