Patient-derived organoids of pancreatic ductal adenocarcinoma for subtype determination and clinical outcome prediction.

BACKGROUND: Recently, two molecular subtypes of pancreatic ductal adenocarcinoma (PDAC) have been proposed: the "Classical" and "Basal-like" subtypes, with the former showing better clinical outcomes than the latter. However, the "molecular" classification has not been applied in real-world clinical practice. This study aimed to establish patient-derived organoids (PDOs) for PDAC and evaluate their application in subtype classification and clinical outcome prediction. METHODS: We utilized tumor samples acquired through endoscopic ultrasound-guided fine-needle biopsy and established a PDO library for subsequent use in morphological assessments, RNA-seq analyses, and in vitro drug response assays. We also conducted a prospective clinical study to evaluate whether analysis using PDOs can predict treatment response and prognosis. RESULTS: PDOs of PDAC were established at a high efficiency (> 70%) with at least 100,000 live cells. Morphologically, PDOs were classified as gland-like structures (GL type) and densely proliferating inside (DP type) less than 2 weeks after tissue sampling. RNA-seq analysis revealed that the "morphological" subtype (GL vs. DP) corresponded to the "molecular" subtype ("Classical" vs. "Basal-like"). The "morphological" classification predicted the clinical treatment response and prognosis; the median overall survival of patients with GL type was significantly longer than that with DP type (P < 0.005). The GL type showed a better response to gemcitabine than the DP type in vitro, whereas the drug response of the DP type was improved by the combination of ERK inhibitor and chloroquine. CONCLUSIONS: PDAC PDOs help in subtype determination and clinical outcome prediction, thereby facilitating the bench-to-bedside precision medicine for PDAC.

Efficacy and safety of streptozocin-based chemotherapy for gastroenteropancreatic neuroendocrine tumors in Japanese clinical practice.

BACKGROUND: Streptozocin has been used to treat neuroendocrine tumors in Europe and the USA; however, its actual status in Japan has not been fully clarified owing to the rarity of this disease and the relatively recent approval of streptozocin in Japan. METHODS: We retrospectively analyzed 53 patients with gastroenteropancreatic neuroendocrine tumors who were treated with streptozocin-based chemotherapy at two Japanese hospitals between January 2004 and June 2023. RESULTS: The overall response and disease control rates were 27.7 and 74.5%, respectively, and the median progression-free survival and overall survival were 7.1 and 20.3 months, respectively. Performance status ≥1 showed a significant negative correlation with progression-free survival, and performance status ≥1 and liver tumor burden ≥25% showed a significant negative correlation with overall survival. No significant differences were observed in the treatment response between pancreatic and gastrointestinal neuroendocrine tumors. No treatment-related serious adverse events were observed; however, 87.7% of patients expressed a decrease in the estimated glomerular filtration rate, which negatively correlated with the duration of streptozocin treatment (r = 0.43, P = 0.0020). In the streptozocin re-administration group (n = 5), no differences were found in efficacy between the initial and second streptozocin treatments. CONCLUSIONS: Although streptozocin is a safe, streptozocin-induced renal dysfunction is a dilemma in streptozocin responders. Streptozocin may benefit patients with gastroenteropancreatic neuroendocrine tumors, especially those with a good performance status; however, in some cases, planned streptozocin withdrawal or switching to other drugs should be considered.

Two cases of pancreatic neuroendocrine tumors with ectopic ACTH syndrome during their disease course.

Pancreatic neuroendocrine tumors (PanNETs) are rare malignant tumors that occur in the pancreas. They are divided into functioning and non-functioning tumors based on the presence or absence of their specific hormonal hyper-expression symptoms. Adrenocorticotropic hormone (ACTH)-producing PanNETs are rare, functional tumors, and their clinical characteristics and outcomes have not been well reported.Here, we report the cases of two patients with PanNETs who presented with ectopic ACTH syndrome (EAS) during the course of their disease. Case 1 involved a non-functioning PanNET at the time of surgery. During treatment for recurrent liver metastases, the patient presented with EAS and tumor-associated hypercalcemia, probably due to ACTH and parathyroid hormone-related peptide (PTHrP) production from the liver tumor. Case 2 was a gastrinoma, and similar to Case 1, this patient presented with EAS during the treatment of recurrent liver metastases.It is not uncommon for patients with PanNETs to have multiple hormones and develop secondary hormone secretion during their disease course, although tumor phenotypes differ between primary and metastatic sites. In patients with functioning PanNETs, symptom control with anti-hormonal therapy is essential, in addition to anti-tumor therapy, especially for EAS, which is an endocrine emergency disease that requires prompt diagnosis and treatment.

Machine learning-based model for prediction and feature analysis of recurrence in pancreatic neuroendocrine tumors G1/G2.

BACKGROUND: Pancreatic neuroendocrine neoplasms (PanNENs) are a heterogeneous group of tumors. Although the prognosis of resected PanNENs is generally considered to be good, a relatively high recurrence rate has been reported. Given the scarcity of large-scale reports about PanNEN recurrence due to their rarity, we aimed to identify the predictors for recurrence in patients with resected PanNENs to improve prognosis. METHODS: We established a multicenter database of 573 patients with PanNENs, who underwent resection between January 1987 and July 2020 at 22 Japanese centers, mainly in the Kyushu region. We evaluated the clinical characteristics of 371 patients with localized non-functioning pancreatic neuroendocrine tumors (G1/G2). We also constructed a machine learning-based prediction model to analyze the important features to determine recurrence. RESULTS: Fifty-two patients experienced recurrence (14.0%) during the follow-up period, with the median time of recurrence being 33.7 months. The random survival forest (RSF) model showed better predictive performance than the Cox proportional hazards regression model in terms of the Harrell's C-index (0.841 vs. 0.820). The Ki-67 index, residual tumor, WHO grade, tumor size, and lymph node metastasis were the top five predictors in the RSF model; tumor size above 20 mm was the watershed with increased recurrence probability, whereas the 5-year disease-free survival rate decreased linearly as the Ki-67 index increased. CONCLUSIONS: Our study revealed the characteristics of resected PanNENs in real-world clinical practice. Machine learning techniques can be powerful analytical tools that provide new insights into the relationship between the Ki-67 index or tumor size and recurrence.

Incidence and appropriate management of drug-induced interstitial lung disease in Japanese patients with unresectable pancreatic cancer: A multicenter retrospective study.

AIM: Drug-induced interstitial lung disease (DI-ILD) is a serious adverse event during chemotherapy. This study aimed to obtain real-world data of the incidence, clinical characteristics, predictive factors, and prognosis of patients with pancreatic cancer who developed DI-ILD. METHODS: In patients with locally advanced or metastatic pancreatic cancer who underwent standard chemotherapy at our hospital and its participating facilities between April 2014 and March 2019, the clinical features, occurrence rate and clinical course of DI-ILD, and prognosis were retrospectively evaluated. RESULTS: Altogether, 390 patients were finally enrolled. DI-ILD occurred in 24 cases (6.2%). The median period from diagnosis of pancreatic cancer to the onset of DI-ILD was 2.2 months (.6-13.3 months). The rate of DI-ILD onset according to each regimen was 5.8% of gemcitabine (GEM) plus albumin-bound paclitaxel therapy (18/308), 3.8% of GEM (4/106), and 2.3% of FOLFIRINOX (2/88). The incidence of DI-ILD in GEM-based regimens was significantly higher than that in non-GEM-based regimens (p < .01). The median overall survival (OS) of the patients with and without DI-ILD after propensity score matching was 11.5 months and 11.4 months (p = .99), respectively. After the resolution of DI-ILD, no statistical significance in the median OS of the patients with and without subsequent treatment (11.0 vs. 6.8 months, p = .18) was observed. CONCLUSION: DI-ILD is not a rare adverse event in the current standard chemotherapy for pancreatic cancer in Japan. With appropriate management of DI-ILD, the prognosis of patients with DI-ILD can be equivalent to that of patients without DI-ILD.

A case of erythema multiforme-like rash induced by everolimus in a patient with a pancreatic neuroendocrine tumor.

A 66-year-old Japanese woman had been diagnosed with a neuroendocrine tumor of the pancreatic head (G2) 3 years previously and undergone pancreaticoduodenectomy. Nine months postoperatively, recurrence with multiple liver metastases developed and she was referred to our department. A regimen of 10 mg of everolimus for 2 weeks plus 1-week washout was instituted, and no adverse events were observed. Fourteen months after treatment initiation, she developed severe generalized erythema multiforme (EM). Skin biopsy revealed spongiosis in the epidermis and interface change and edema in the superficial dermis. Mast cells were observed from the dermis to the subcutaneous tissue, as well as perivascular eosinophilic infiltration, leading to EM being diagnosed. Oral everolimus was discontinued, and the EM was relieved by treatment including steroid therapy. Everolimus is an inhibitor of the mammalian target of rapamycin, and its indications include neuroendocrine tumors. Skin disorders are commonly seen in the early stages of everolimus treatment, but their severity is almost always mild and never severe. This is the first report on a patient who presented with severe generalized EM more than 1 year after everolimus treatment initiation. Patients on everolimus therapy should be monitored for skin disorders on a long-term basis.

Treatment Effect and Safety of Nanoliposomal Irinotecan with Fluorouracil and Folinic Acid after Gemcitabine-Based Therapy in Patients with Advanced Pancreatic Cancer: A Multicenter, Prospective Observational Study.

Although the combination of nanoliposomal irinotecan plus fluorouracil/folinic acid (nal-IRI/FF) exhibited survival benefits in gemcitabine-refractory patients with advanced pancreatic cancer (APC) in the phase III NAPOLI-1 trial, there is limited data on the efficacy and safety of this regimen in real-world settings in Japan. This multicenter, prospective observational study enrolled patients with APC who received nal-IRI/FF after a gemcitabine-based regimen from July 2020 to June 2021. We collected and analyzed clinical data and conducted survival and multivariate analyses. Thirty-one (78%) of the 40 patients had metastases. Nal-IRI/FF was the second-line therapy in 36 patients (90%). The median duration was 3.2 months. The disease control rate was 57%. The median progression-free survival and overall survival (OS) were 4.5 months (95% confidence interval [CI]: 2.8−5.5) and 7.4 months (95% CI: 5.1−10.6), respectively. Common ≥grade 3 toxicities included neutropenia (28%) and fatigue (23%). Fatigue led to treatment discontinuation in 6 out of 10 patients. Multivariate analysis showed that a neutrophil-to-lymphocyte ratio > 4 was a significant risk factor for a short OS (hazard ratio (HR) = 3.08, 95% CI: 1.21−7.85, p = 0.02). In conclusion, nal-IRI/FF is an appropriate treatment option for APC following gemcitabine-containing regimens.

A clinical analysis on functioning pancreatic neuroendocrine tumors (focusing on VIPomas): a single-center experience.

VIPomas are generally rare functioning pancreatic neuroendocrine tumors (PanNETs) that cause watery diarrhea, hypokalemia, and achlorhydria. Due to their extreme rarity, the clinicopathological features and outcomes of VIPomas have not been well reported. This study aimed to determine the diagnostic and therapeutic characteristics and prognosis of VIPomas and to compare them with other PanNETs at a Japanese reference hospital. Medical records of 293 patients with PanNETs were collected. Patient and tumor characteristics and outcomes were retrospectively reviewed. This cohort had only 1.4% (four patients) of patients with VIPomas, and three of these patients changed from non-functioning (NF-) PanNETs during their disease course. Recurrences of hormonal symptoms were observed in all patients despite the initial controls, and all of them died from their disease, more specifically mainly from hormonal symptoms. Compared to the other PanNETs, VIPomas were all located at the pancreatic tail, were larger, and had a higher Ki-67 index and more metastasis. The median survival time was significantly shorter for patients with VIPoma than for those with NF-PanNET (5.9 vs. 26.7 years, p < 0.0001), insulinoma (21.8 years, p < 0.0001), and gastrinoma (12.3 years, p = 0.0325). This study presents the possibility of shifting from non-symptomatic to symptomatic VIPomas as they grow or of transforming from NF-PanNETs to VIPomas. VIPomas should be considered in patients with relatively large NF-PanNETs, especially those located in the pancreatic tail, when diarrhea is continuously observed. As hormonal symptoms are an important cause of death in VIPomas, long-term symptomatic control, which is relatively difficult, is of great significance.

Endoscopic Transpapillary Pancreatic Duct Stent Placement for Symptomatic Peripancreatic Fluid Collection Caused by Clinically Relevant Postoperative Pancreatic Fistula After Distal Pancreatectomy.

This study aimed to evaluate the safety and efficacy of endoscopic transpapillary pancreatic duct stent placement (ETPS) for symptomatic peripancreatic fluid collection caused by postoperative pancreatic fistula (POPF) after distal pancreatectomy (DP). ETPS was also compared with percutaneous drainage (PTD). Retrospectively 38 patients were studied who developed clinically relevant POPF. Of 38 patients, 4 underwent PTD and 11 underwent ETPS. Technical and clinical success rates of ETPS (100% and 91%, respectively) were comparable with PTD (100% and 75%, respectively). The tip of a pancreatic stent was placed over the pancreatic stump in 4 patients and draining of pus through the pancreatic stent was observed. The hospital stay after DP and the interval from intervention to discharge were significantly shorter in the ETPS group than in the PTD group. ETPS is safe and successful for managing peripancreatic fluid collection caused by POPF after DP and should be considered as a therapeutic option.

The validity of the surgical indication for intraductal papillary mucinous neoplasm of the pancreas advocated by the 2017 revised International Association of Pancreatology consensus guidelines.

PURPOSE: This study was performed to evaluate the surgical indication for intraductal papillary mucinous neoplasm (IPMN) advocated by the 2017 revised International Association of Pancreatology consensus guidelines (IAPCG2017). METHODS: The medical records of 63 patients who underwent pancreatectomy for IPMN were retrospectively reviewed. RESULTS: Thirteen patients had main-duct IPMN, 25 had mixed IPMN, and 25 had branch-duct IPMN with frequencies of high-grade dysplasia or invasive carcinoma of 62, 24, and 28%, respectively. The sensitivity and specificity of high-risk stigmata for high-grade dysplasia or invasive carcinoma advocated by the IAPCG2017 were 90 and 67%, respectively. Of 17 patients with invasive carcinoma, all patients had high-risk stigmata, and 16 had an enhanced mural nodule (MN) of ≥ 5 mm. The sensitivity and specificity of a ≥ 5-mm enhanced MN for predicting invasive carcinoma were 94% and 87%, respectively. CONCLUSIONS: Introducing a size threshold for enhanced MNs into the assessment of high-risk stigmata increases the specificity without jeopardizing the sensitivity. The surgical indication for any type of IPMN may be determined using only a ≥ 5-mm enhanced MN. When the type of IPMN is classified strictly, about half of IPMNs are mixed type, and most are benign. The surgical indication for mixed IPMN should be reconsidered.

Multi-center clinical evaluation of streptozocin-based chemotherapy for advanced pancreatic neuroendocrine tumors in Japan: focus on weekly regimens and monotherapy.

PURPOSE: Streptozocin (STZ) is a key agent for treating advanced pancreatic neuroendocrine tumors (pNET). Most STZ regimens for pNET are daily and also include 5-fluorouracil (5FU), whereas STZ monotherapy and weekly regimens have also been applied in daily practice in Japan. The present study aimed to evaluate responses to weekly regimens and to STZ monotherapy, and to identify a predictive marker of a response to STZ. METHODS: Clinical data regarding STZ-based chemotherapy for pNET were collected between 2015 and 2017 at 25 facilities. We analyzed the effects, safety, progression-free survival (PFS), and factors that correlate with responses to STZ. RESULTS: The overall objective response rate (ORR) of 110 patients who underwent STZ-based chemotherapy (monotherapy, 81.8%; weekly regimen 46.4%) was 21.8%, and PFS was 9.8 months. The ORR of weekly vs. daily regimens was 21.6 vs. 22.0% (P = 1.000), and that of monotherapy vs. combination therapy was 21.1 vs. 25.0% (P = 0.766). A Ki67 proliferation index (Ki67) of > 5% was a predictive marker of a response to STZ (P = 0.017), whereas regimen type, mono- or combination therapy, treatment line and liver tumor burden were not associated with responses. The frequencies of Grade ≥ 3 nausea and hematological adverse events were significantly lower for monotherapy than combination therapy (P = 0.032). CONCLUSIONS: The effects of weekly STZ monotherapy on pNET are comparable to those previously reported and the toxicity profile was acceptable. Ki67 > 5% was the sole predictive marker of an objective response.

Using CRISPR/Cas9 to Knock out Amylase in Acinar Cells Decreases Pancreatitis-Induced Autophagy.

Pancreatic cancer is a malignant neoplasm that originates from acinar cells. Acinar cells get reprogrammed to become duct cells, resulting in pancreatic cancer. Pancreatitis is an acinar cell inflammation, leading to "impaired autophagy flux". Pancreatitis promotes acinar-to-ductal transdifferentiation. Expression of amylase gets eliminated during the progression of pancreatic cancer. Amylase is considered as an acinar cell marker; however, its function in cells is not known. Thus, we investigated whether amylase affects the acinar cell autophagy and whether it plays any role in development of pancreatitis. Here, we knocked out ATG12 in a pancreatic cancer cells and acinar cells using CRISPR/Cas9. Autophagy inhibition led to an increase in the expression of duct cell markers and a simultaneous decrease in that of acinar cell markers. It also caused an increase in cell viability and changes in mitochondrial morphology. Next, we knocked out amylase in acinar cells. Amylase deficiency decreased autophagy induced by pancreatitis. Our results suggest that amylase controls pancreatitis-induced autophagy. We found that eliminating amylase expression contributes to pancreatic cancer etiology by decreasing autophagy. Furthermore, our results indicate that amylase plays a role in selective pancreatitis-induced autophagy of pancreatic enzyme vesicles.

Should the Selective Arterial Secretagogue Injection Test for Insulinoma Localization Be Evaluated at 60 or 120 Seconds?

Objective The selective arterial secretagogue injection (SASI) test is considered indispensable for the accurate localization of insulinoma. However, the optimum timing of the post-injection evaluation is controversial, as some studies recommend 60 seconds [SASI (60 seconds)] while others support 120 seconds [SASI (120 seconds)]. The aim of this study was to determine the optimum timing for the SASI test evaluation for insulinoma localization. Methods Thirteen patients with surgically proven insulinoma were studied retrospectively. For the SASI test, immunoreactive insulin (IRI) was determined at baseline and at 30, 60, 90, and 120 seconds after calcium gluconate injection. A two-fold or greater increase in IRI over the baseline value was considered positive. The localization abilities of SASI (60 seconds) and SASI (120 seconds) were then compared. Results In 13 patients, a secretagogue was injected into 40 arteries supplying the pancreas. In the SASI (60 seconds) and SASI (120 seconds), the respective findings were as follows: positive predictive value, 72.2% and 68.2%; false positive rate, 25.0% and 35.0%; and rate of positivity in the head and body/tail, 38.5% and 46.2%. When the artery with the largest change was taken as the dominant artery, the localization detection sensitivity was 76.9% for SASI (60 seconds) and 92.3% for SASI (120 seconds). The sensitivity of morphological imaging techniques for localization ranged from 61.5-91.7%. Conclusion Compared with SASI (60 seconds) or morphological imaging, the insulinoma localization ability of SASI (120 seconds) was superior. Given these findings, we believe that the IRI level should be measured at 120 seconds in the SASI test.

Serum levels of Wisteria floribunda agglutinin-positive Mac-2 binding protein reflect the severity of chronic pancreatitis.

OBJECTIVES: To evaluate the utility of serum Wisteria floribunda agglutinin-positive Mac-2 binding protein (WFA + -M2BP) level as a marker for chronic pancreatitis (CP). METHODS: We measured the serum WFA+ -M2BP level of 74 patients with CP who had undergone endoscopic retrograde cholangiopancreatography and 30 normal controls (NC) using a glycan sugar chain-based immunoassay and investigated the relationship between serum WFA+ -M2BP levels and the Cambridge classification of CP. RESULTS: Serum WFA+ -M2BP level was significantly higher in patients with CP than in NC (0.64 ± 0.28 vs 0.34 ± 0.25, P < 0.001). The levels (expressed as cut-off index) of WFA+ -M2BP for the classification of mild, moderate and marked CP were 0.44, 0.63 and 0.87, respectively. Thus, serum WFA+ -M2BP levels increased with increasing CP severity. With a cut-off value of 0.34, 0.59 and 0.61, the area under the receiver operating characteristic curve, sensitivity and specificity were 0.829, 91.9% and 63.3% for mild CP; 0.891, 81.8% and 85.0% for moderate CP; and 0.888, 92.0% and 74.7% for marked CP, respectively. Multivariate analysis revealed that elevated serum WFA+ -M2BP was independently associated with moderate and marked CP, respectively. CONCLUSION: Serum WFA+ -M2BP level is a useful marker for grading CP severity.

Utility of chromogranin B compared with chromogranin A as a biomarker in Japanese patients with pancreatic neuroendocrine tumors.

OBJECTIVE: Currently, serum chromogranin A is a well-established biomarker for pancreatic neuroendocrine tumors; however, other pancreatic diseases, oral use of a proton pump inhibitor and renal impairment can affect chromogranin A. Meanwhile, chromogranin B, belonging to the same granin family as chromogranin A, is not fully examined in these conditions. The present study aimed to evaluate the utility of chromogranin B as a pancreatic neuroendocrine tumor biomarker. METHODS: Serum chromogranin B levels were determined by radioimmunoassay and serum chromogranin A levels by enzyme-linked immunosorbent assay in pancreatic neuroendocrine tumor (n = 91) and other pancreatic conditions, and in healthy people (n = 104), to assess the relationships with clinical features. RESULTS: The diagnostic ability of chromogranin B was as good as chromogranin A. The area under the curve was 0.79 for chromogranin B (sensitivity/specificity: 72%/77%), and 0.78 for chromogranin A (sensitivity/specificity: 79%/64%). Chromogranin B was not affected by proton pump inhibitor use and age, which affected chromogranin A. The number of cases without liver metastases was larger in pancreatic neuroendocrine tumor patients with positive chromogranin B and negative chromogranin A. Though chromogranin A significantly elevated cases with proton pump inhibitor treatment and had positive correlation with age, chromogranin B did not have the tendencies. However, both chromogranin B and chromogranin A elevated in the case with renal impairment. In addition, the logistic regression analysis showed that chromogranin B was superior to chromogranin A in differentiation of pancreatic neuroendocrine tumor from other pancreatic diseases. CONCLUSIONS: Compared with chromogranin A, chromogranin B may be more useful during proton pump inhibitor treatment and can detect tumors without liver metastases. In addition, chromogranin B may be an excellent biomarker when differentiation of pancreatic neuroendocrine tumor from other pancreatic diseases is required.

Diagnostic Performance of 48-Hour Fasting Test and Insulin Surrogates in Patients With Suspected Insulinoma.

OBJECTIVES: This study aimed to evaluate the usefulness of the 48-hour fasting test and insulin surrogates followed by a glucagon stimulatory test (GST) for the diagnosis of insulinoma. METHODS: Thirty-five patients with suspected insulinoma who underwent 48-hour fasting test and GST were retrospectively included in our study: 15 patients with surgically proven insulinomas and 20 patients in whom insulinoma was clinically ruled out. We determined the duration of the fasting test, plasma glucose levels, serum levels of immunoreactive insulin and C-peptide, and insulin surrogates (serum levels of ß-hydroxybutyrate, free fatty acid, and response of plasma glucose to intravenous glucagon [ΔPG]) at the end of the fast. RESULTS: The sensitivity and specificity of the 48-hour fasting test were 100.0% and 80.0%, respectively, for the diagnosis of insulinoma. When the 48-hour fasting test and immunoreactive insulin, C-peptide, or insulin surrogates were combined, the combination with GST showed the best results. The sensitivity, specificity, and accuracy rate were 93.3%, 95.0%, and 94.3%, respectively, with 1 false-negative case and 1 false-positive case occurring. CONCLUSIONS: A more accurate and less invasive diagnosis of insulinoma was possible by combining the 48-hour fasting test with the GST, compared with the existing method.

Impact of everolimus on Japanese patients with advanced pancreatic neuroendocrine neoplasms.

BACKGROUND: Although everolimus has become a key therapeutic agent in patients with advanced pancreatic neuroendocrine neoplasms (PNEN), its efficacy and safety in clinical practice remains unclear. METHODS: Forty-seven patients with advanced PNEN treated with everolimus were reviewed retrospectively. To evaluate the safety of everolimus as a long-term treatment, the patients were divided into two groups according to treatment duration: group A, ≤1 year (n = 21); group B, >1 year (n = 26). RESULTS: Among 42 patients with pancreatic neuroendocrine tumors (PNET), the median progression-free survival, overall survival, and objective response rate were 27.5 months, 60.8 months, and 19.0%, respectively. Two patients with pancreatic neuroendocrine carcinomas (PNEC) with lower Ki-67 index and well-differentiated tumors showed favorable responses. More patients in group A discontinued everolimus owing to adverse drug reactions (ADRs) than in group B. The median relative dose intensity was significantly lower in group B than group A (P = 0.045), whereas the drug interruption rate was significantly higher in group B than group A (P < 0.001). CONCLUSIONS: Everolimus showed significant clinical benefit in Japanese patients with advanced PNEN. Prevention of severe ADRs by appropriate dose reduction and interruption is necessary for a long-term continuation of everolimus.