Long-term activation of anti-tumor immunity in pancreatic cancer by a p53-expressing telomerase-specific oncolytic adenovirus.

BACKGROUND: Pancreatic cancer is an aggressive, immunologically "cold" tumor. Oncolytic virotherapy is a promising treatment to overcome this problem. We developed a telomerase-specific oncolytic adenovirus armed with p53 gene (OBP-702). METHODS: We investigated the efficacy of OBP-702 for pancreatic cancer, focusing on its long-term effects via long-lived memory CD8 + T cells including tissue-resident memory T cells (TRMs) and effector memory T cells (TEMs) differentiated from effector memory precursor cells (TEMps). RESULTS: First, in vitro, OBP-702 significantly induced adenosine triphosphate (ATP), which is important for memory T cell establishment. Next, in vivo, OBP-702 local treatment to murine pancreatic PAN02 tumors increased TEMps via ATP induction from tumors and IL-15Rα induction from macrophages, leading to TRM and TEM induction. Activation of these memory T cells by OBP-702 was also maintained in combination with gemcitabine+nab-paclitaxel (GN) in a PAN02 bilateral tumor model, and GN + OBP-702 showed significant anti-tumor effects and increased TRMs in OBP-702-uninjected tumors. Finally, in a neoadjuvant model, in which PAN02 cells were re-inoculated after resection of treated-PAN02 tumors, GN + OBP-702 provided long-term anti-tumor effects even after tumor resection. CONCLUSION: OBP-702 can be a long-term immunostimulant with sustained anti-tumor effects on immunologically cold pancreatic cancer.

Oncolytic virus-mediated reducing of myeloid-derived suppressor cells enhances the efficacy of PD-L1 blockade in gemcitabine-resistant pancreatic cancer.

Pancreatic ductal adenocarcinoma (PDAC) is often refractory to treatment with gemcitabine (GEM) and immune checkpoint inhibitors including anti-programmed cell death ligand 1 (PD-L1) antibody. However, the precise relationship between GEM-resistant PDAC and development of an immunosuppressive tumor microenvironment (TME) remains unclear. In this study, we investigated the immunosuppressive TME in parental and GEM-resistant PDAC tumors and assessed the therapeutic potential of combination therapy with the telomerase-specific replication-competent oncolytic adenovirus OBP-702, which induces tumor suppressor p53 protein and PD-L1 blockade against GEM-resistant PDAC tumors. Mouse PDAC cells (PAN02) and human PDAC cells (MIA PaCa-2, BxPC-3) were used to establish GEM-resistant PDAC lines. PD-L1 expression and the immunosuppressive TME were analyzed using parental and GEM-resistant PDAC cells. A cytokine array was used to investigate the underlying mechanism of immunosuppressive TME induction by GEM-resistant PAN02 cells. The GEM-resistant PAN02 tumor model was used to evaluate the antitumor effect of combination therapy with OBP-702 and PD-L1 blockade. GEM-resistant PDAC cells exhibited higher PD-L1 expression and produced higher granulocyte-macrophage colony-stimulating factor (GM-CSF) levels compared with parental cells, inducing an immunosuppressive TME and the accumulation of myeloid-derived suppressor cells (MDSCs). OBP-702 significantly inhibited GEM-resistant PAN02 tumor growth by suppressing GM-CSF-mediated MDSC accumulation. Moreover, combination treatment with OBP-702 significantly enhanced the antitumor efficacy of PD-L1 blockade against GEM-resistant PAN02 tumors. The present results suggest that combination therapy involving OBP-702 and PD-L1 blockade is a promising antitumor strategy for treating GEM-resistant PDAC with GM-CSF-induced immunosuppressive TME formation.

Local oncolytic adenovirotherapy produces an abscopal effect via tumor-derived extracellular vesicles.

Extracellular vesicles (EVs) play important roles in various intercellular communication processes. The abscopal effect is an interesting phenomenon in cancer treatment, in which immune activation is generally considered a main factor. We previously developed a telomerase-specific oncolytic adenovirus, Telomelysin (OBP-301), and occasionally observed therapeutic effects on distal tumors after local treatment in immunodeficient mice. In this study, we hypothesized that EVs may be involved in the abscopal effect of OBP-301. EVs isolated from the supernatant of HCT116 human colon carcinoma cells treated with OBP-301 were confirmed to contain OBP-301, and they showed cytotoxic activity (apoptosis and autophagy) similar to OBP-301. In bilateral subcutaneous HCT116 and CT26 tumor models, intratumoral administration of OBP-301 produced potent antitumor effects on tumors that were not directly treated with OBP-301, involving direct mediation by tumor-derived EVs containing OBP-301. This indicates that immune activation is not the main factor in this abscopal effect. Moreover, tumor-derived EVs exhibited high tumor tropism in orthotopic HCT116 rectal tumors, in which adenovirus E1A and adenovirus type 5 proteins were observed in metastatic liver tumors after localized rectal tumor treatment. In conclusion, local treatment with OBP-301 has the potential to produce abscopal effects via tumor-derived EVs.

Surgical technique of suprapancreatic D2 lymphadenectomy focusing on the posterior hepatic plexus for advanced gastric cancer.

PURPOSE: Although D2 lymphadenectomy is currently considered a standard procedure for advanced gastric cancer (GC) worldwide, there is room for discussion about the appropriate range of suprapancreatic D2 lymphadenectomy. Focusing on the posterior hepatic plexus (PHP), which is not well recognized, we developed a surgical technique of suprapancreatic D2 lymphadenectomy, which we have called PHP-D2, and its short-term and long-term efficacies were evaluated in comparison with non-PHP-D2. METHODS: GC patients who underwent distal gastrectomy with D2 lymphadenectomy between July 2006 and May 2013 were enrolled, from which patients who had peritoneal metastasis and/or were peritoneal cytology-positive during surgery were excluded. Their medical records were retrospectively reviewed. RESULTS: Ninety-two patients (non-PHP-D2: 48, PHP-D2: 44) were enrolled. Shorter operation time (330 min vs 275 min, p < 0.0001) and less blood loss (290 mL vs 125 mL, p < 0.0001) were observed in PHP-D2, and no pancreatic fistulas were observed in PHP-D2. More lymph nodes of #11p (1 vs 1.5, p = 0.0328) and #12a lymph nodes (0 vs 1, p = 0.0034) were retrieved in PHP-D2, with no significant differences in #8a and #9 lymph nodes. Lymphatic recurrence was significantly less in PHP-D2 (p = 0.0166), and univariate and multivariate analyses showed that non-PHP-D2 was a significant risk factor for lymphatic recurrence (p = 0.0158), although there were no significant differences between non-PHP-D2 and PHP-D2 in 5-year overall survival and 5-year relapse-free survival. CONCLUSION: PHP-D2 was a safe and feasible procedure that had the potential to reduce lymphatic recurrence, and it can be a standard procedure of D2 lymphadenectomy for advanced GC.

[Telomerase-Specific Oncolytic Adenovirus Expressing p53 Gene Stimulating CD8+ Memory T Cells in Pancreatic Cancer].

Pancreatic cancer has poor prognosis despite the various developed multimodal treatment strategies. Currently, neoadjuvant chemotherapy and immunotherapy have attracted substantial attention as effective treatment strategies. However, amplifying immune response with existing treatments is difficult. We developed telomerase-specific oncolytic adenoviruses (OAs), including OBP-301 that is currently tested in a clinical trial of combined anti-PD-1 antibody and p53-armed OBP- 301 variant(OBP-702). OAs have immune-modulation functions and induce CD8+ T cells into tumors by releasing immunogenic cell death markers, such as extracellular adenosine triphosphate. Here, we investigated the effectiveness of OBP- 702 in pancreatic cancer treatments, focusing on the influence on CD8+ memory T cells.

Immune Modulation by Telomerase-Specific Oncolytic Adenovirus Synergistically Enhances Antitumor Efficacy with Anti-PD1 Antibody.

The clinical benefit of monotherapy involving immune checkpoint inhibitors (ICIs) such as anti-programmed death-1 antibody (PD-1 Ab) is limited to small populations. We previously developed a telomerase-specific oncolytic adenovirus, Telomelysin (OBP-301), the safety of which was confirmed in a phase I clinical study. Here, we examined the potential of OBP-502, an OBP-301 variant, as an agent for inducing immunogenic cell death (ICD) and synergistically enhancing the efficacy of OBP-502 with PD-1 Ab using CT26 murine colon cancer and PAN02 murine pancreatic cancer cell lines. OBP-502 induced the release of ICD molecules such as adenosine triphosphate (ATP) and high-mobility group box protein 1 (HMGB1) from CT26 and PAN02 cells, leading to recruitment of CD8-positive lymphocytes and inhibition of Foxp3-positive lymphocyte infiltration into tumors. Combination therapy involving OBP-502 intratumoral administration and PD-1 Ab systemic administration significantly suppressed the growth of not only OBP-502-treated tumors but also tumors not treated with OBP-502 (so-called abscopal effect) in CT26 and PAN02 bilateral subcutaneous tumor models, in which active recruitment of CD8-positve lymphocytes was observed even in tumors not treated with OBP-502. This combined efficacy was similar to that observed in a CT26 rectal orthotopic tumor model involving liver metastases. In conclusion, telomerase-specific oncolytic adenoviruses are promising candidates for combined therapies with ICIs.

HER2-targeted gold nanoparticles potentially overcome resistance to trastuzumab in gastric cancer.

An issue of concern is that no current HER2-targeted therapeutic agent is effective against Trastuzumab (Tmab)-resistant gastric cancer. Gold nanoparticles (AuNPs) are promising drug carriers with unique characteristics of a large surface area available for attachment of materials such as antibodies. Here, we created HER2-targeted AuNPs (T-AuNPs) and examined their therapeutic efficacy and cytotoxic mechanisms using HER2-postive Tmab-resistant (MKN7) or Tmab-sensitive (NCI-N87) gastric cancer cell lines. In vitro, T-AuNPs showed stronger cytotoxic effects than controls against MKN7 and NCI-N87 cells although Tmab had no effect on MKN7 cells. Autophagy played an important role in T-AuNP cytotoxic mechanisms, which was considered to be driven by internalization of T-AuNPs. Finally, T-AuNPs displayed potent antitumor effects against NCI-N87 and MKN7 subcutaneous tumors in in vivo mouse models. In conclusion, HER2-targeted AuNPs with conjugated Tmab is a promising strategy for the development of novel therapeutic agents to overcome Tmab resistance in gastric cancer.

[Novel Therapeutic Strategy for Human Epidermal Growth Factor Receptor 2-Positive Gastric Cancer].

Trastuzumab(Tmab), a humanized monoclonal antibody that selectively targets human epidermal growth factor receptor 2(HER2), is currently used in the clinical setting for the treatment of both breast and gastric cancer. While Tmab has shown improvements in patient prognoses, acquired resistance to this agent remains an issue. While some novel HER2-targeted agents have been approved for clinical use in breast cancer, no such agent has shown treatment efficacy for gastric malignancies with Tmab-resistance. Nanotechnology, which has progressed rapidly, has been applied to medical fields in recent years. Gold nanoparticles, which are characterized by their in vivo stability and ease of surface modification, have been reported to show efficacy as the carriers of therapeutic agents, such as drugs, antibodies, peptides, and nucleic acids. In this work, we developed Tmab-conjugated gold nanoparticles and demonstrate their efficacy for the treatment of HER2-positive, Tmabresistant gastric cancer cell lines. Our findings demonstrate that Tmab-conjugated gold nanoparticles have the potential to be a novelHER2 -targeted therapeutic agent.

Granulocyte Colony-Stimulating Factor-Producing Gallbladder Cancer.

We report a case of a granulocyte colony-stimulating factor (G-CSF)-producing gallbladder tumor associated with fever in a middle-aged female. Preoperative blood analysis showed leukocytosis with elevated levels of C-reactive protein and G-CSF. We resected the liver at S4a＋S5, with regional lymph node dissection and partial resection of the duodenum. Histology revealed undifferentiated carcinoma with spindle and giant cells and papillary adenocarcinoma. Immunohistochemistry revealed Stage IIIB G-CSF-producing gallbladder cancer. Postoperatively, leukocyte and serum G-CSF levels decreased to within normal limits. Adjuvant gemcitabine chemotherapy was administered for 16 months, and she has been recurrence-free for 48 months.

[A case of HER2-positive esophagogastric junction cancer treated by using a neoadjuvant chemotherapy regimen consisting of trastuzumab].

The case herein pertains to a 78-year-old man, who was referred to our department and in whom esophagogastric junctional cancer, triggering weight loss, was indicated. A 0.75 xx circumferential Type 3 lesion was observed in the esophagogastric junction via upper gastrointestinal endoscopy, and a biopsy revealed a moderately differentiated adenocarcinoma with overexpression of human epidermal growth factor type 2 (HER2). Contrast-enhanced computed tomography (CT) showed multiple enlarged lymph nodes on the lesser curvature of the stomach. The preoperative diagnosis was T4a (SE) N2M0, Stage IIIB esophagogastric adenocarcinoma. Four courses of preoperative chemotherapy consisting of capecitabine plus cisplatin and trastuzumab were administered. The primary lesion showed cicatrization after chemotherapy, and enlarged lymph nodes were not visible on a CT scan. Total gastrectomy, splenectomy, and D2 lymph node dissection were performed. Only a small amount (approximately 5 mm) of the primary lesion remained beneath the abdominal and esophageal mucosa, and the treatment effectiveness was Grade 2. The final diagnosis was T1b (SM) N0M0, Stage IA esophagogastric adenocarcinoma. Survival with no recurrence was confirmed 6 months after surgery. These findings suggest that inclusion of trastuzumab in preoperative chemotherapy regimens improves the degree of curability of HER2-positive esophagogastric junction cancers.

[Tumor-infiltrating lymphocytes can be used to screen for lynch syndrome - a case report].

Lynch syndrome is an inherited syndrome associated with the development of colorectal and various other cancers. A 65- year-old male underwent a laparoscopic-assisted right hemi-colectomy for ascending colon cancer (cStage II). Histologically, his tumor was diagnosed as a poorly differentiated adenocarcinoma. Lymphocytic reactions, such as tumor-infiltrating lymphocytes (TIL), and Crohn's-like reactions, were observed. Genetic testing revealed the presence of a pathogenic mutation in the MLH1. In the Lynch syndrome, the most frequently observed findings include the accumulation of mutations, and an early onset of familial colon cancer. Although the case presented here did not show the typical clinical findings of Lynch syndrome, histological examination of the lymphocytic reactions proved useful for screening for Lynch syndrome. Herein, we establish the important role of the pathologist in alerting the clinician to the possibility of Lynch syndrome when the findings of TIL and Crohn's-like reactions are detected.

[A case of gastric cancer developed after pylorus-preserving gastrectomy in a patient with lynch syndrome].

Lynch syndrome is an inherited autosomal dominant disorder caused by germ-line mutation of mismatch repair genes, in which a malignant tumor develops at a young age in the colon, endometrium, stomach, or other tissues. A 54-year-old patient with gastric cancer received pylorus-preserving gastrectomy, and a genetic examination confirmed a pathological variation of the MLH1 gene. Five years after surgery, an upper gastrointestinal endoscopy revealed a residual 0 -IIa+IIc gastric tumor approximately 2 cm in size extending from the anastomotic site to the lesser curvature side of the stomach. The remaining stomach was completely removed. The final diagnosis was T1b (SM) N1M0, StageIB gastric cancer. Microsatellite instability was positive, and we attributed the cancer to Lynch syndrome. In Lynch syndrome, the risk of multicentric gastric cancer is higher than normal, and for the initial therapy, preventive total gastrectomy should be considered as an option.

[A case of lynch syndrome treated laparoscopically for multiple colon cancers].

Lynch syndrome is an inherited syndrome associated with the development of colorectal, endometrial, stomach, and other cancers; it is caused by defects in the mismatch repair genes. Such patients are at risk of developing multiple abdominal cancers after colectomy, and the presence of adhesions may render future abdominal surgeries difficult. We recommend that patients with Lynch syndrome should be considered good candidates for laparoscopic surgery. A 43-year-old Japanese man was admitted following a positive fecal occult blood test result. The patient was diagnosed with multiple colon cancers in the right colon. He had undergone endoscopic mucosal resection for a colon polyp when he was 24 years of age. Two people among his father's second-degree relatives had colorectal cancer, and he fulfilled the revised Bethesda guidelines. He underwent laparoscopic-assisted right hemicolectomy and D3 lymph node dissection. Microsatellite instability testing indicated the presence of MSI-H, and genetic testing demonstrated a pathogenic mutation of MLH-1.

[A case of advanced colon cancer with multiple liver metastases treated by two-stage laparoscopic surgery].

We report a case of advanced colon cancer with multiple liver metastases treated by two-stage laparoscopic surgery. An 82-year-old woman, whose main complaint was constipation, was diagnosed with stage IV sigmoid colon cancer. With the aim of decompressing the colon, a transanal decompression tube was inserted. She underwent laparoscopic-assisted sigmoidectomy and D3 lymph node dissection, and an ileostomy was created. Systemic chemotherapy was administered immediately after the operation. After 4 courses of chemotherapy, she underwent the second operation, i.e., laparoscopic- assisted partial hepatectomy and radiofrequency ablation of liver metastases. Cases of obstructive colon cancer are more advanced than cases of non-obstructive colon cancer. Systemic treatments are required after the resection of primary tumors. We aim to improve the prognosis of patients with obstructive colon cancer by the use of laparoscopic surgery.

Exosomes as a drug delivery tool for cancer therapy: a new era for existing drugs and oncolytic viruses.

INTRODUCTION: Exosomes are cell-derived nanovesicles involved in cell-to-cell communications. These nanovesicles are generally considered to contain important carriers of information such as DNA and RNA, and show specific tropism. AREAS COVERED: The combination of existing therapeutic agents with exosomes enhances therapeutic effects by increasing uptake into the tumor. Induction of immunogenic cell death (ICD) may also be triggered more strongly than with the drug alone. Oncolytic viruses (OVs) are even more effective as a drug in combination with exosomes. Although OVs are more likely to cause immune activity, combination with exosomes can exert synergistic effects. OVs have potent anti-tumor effects, but many limitations, such as being limited to local administration and vulnerability to attack by antibodies. Incorporation into exosomes can overcome these limitations and may allow effects against distant tumors. EXPERT OPINION: Novel therapies using exosomes are very attractive in terms of enhancing therapeutic efficacy and reducing side effects. This approach also contains elements overcoming disadvantages in OVs, which have not been used clinically until now, and may usher in a new era of cancer treatments.

Two Cases of Thymic Cancer in Patients with Lynch Syndrome.

We herein report two cases of thymic cancer with Lynch syndrome showing a high frequency of microsatellite instability and loss of mismatch repair protein expression without MLH1 promoter hyper-methylation. In Case 1, a 71-year-old man had a pathogenic germline variant in MLH1 and underwent tumor resection. No relapse has been reported thus far. In Case 2, a 43-year-old man underwent genetic testing that also showed a pathogenic germline variant in MLH1. Since these two cases had MLH variants, we suspect a possible association between thymic cancer with Lynch syndrome and germline pathogenic variants in MLH1.

Fate and Efficacy of Engineered Allogeneic Stem Cells Targeting Cell Death and Proliferation Pathways in Primary and Brain Metastatic Lung Cancer.

Primary and metastatic lung cancer is a leading cause of cancer-related death and novel therapies are urgently needed. Epidermal growth factor receptor (EGFR) and death receptor (DR) 4/5 are both highly expressed in primary and metastatic non-small cell lung cancer (NSCLC); however, targeting these receptors individually has demonstrated limited therapeutic benefit in patients. In this study, we created and characterized diagnostic and therapeutic stem cells (SC), expressing EGFR-targeted nanobody (EV) fused to the extracellular domain of death DR4/5 ligand (DRL) (EVDRL) that simultaneously targets EGFR and DR4/5, in primary and metastatic NSCLC tumor models. We show that EVDRL targets both cell surface receptors, and induces caspase-mediated apoptosis in a broad spectrum of NSCLC cell lines. Utilizing real-time dual imaging and correlative immunohistochemistry, we show that allogeneic SCs home to tumors and when engineered to express EVDRL, alleviate tumor burden and significantly increase survival in primary and brain metastatic NSCLC. This study reports mechanistic insights into simultaneous targeting of EGFR- and DR4/5 in lung tumors and presents a promising approach for translation into the clinical setting.

Gene-edited and -engineered stem cell platform drives immunotherapy for brain metastatic melanomas.

Oncolytic virus therapy has shown activity against primary melanomas; however, its efficacy in brain metastases remains challenging, mainly because of the delivery and immunosuppressive nature of tumors in the brain. To address this challenge, we first established PTEN-deficient melanoma brain metastasis mouse models and characterized them to be more immunosuppressive compared with primary melanoma, mimicking the clinical settings. Next, we developed an allogeneic twin stem cell (TSC) system composed of two tumor-targeting stem cell (SC) populations. One SC was loaded with oncolytic herpes simplex virus (oHSV), and the other SC was CRISPR-Cas9 gene-edited to knock out nectin 1 (N1) receptor (N1KO) to acquire resistance to oHSV and release immunomodulators, such as granulocyte-macrophage colony-stimulating factor (GM-CSF). Using mouse models of brain metastatic BRAFV600E/PTEN-/- and BRAFV600E/wt/PTEN-/- mutant melanomas, we show that locoregional delivery of TSCs releasing oHSV and GM-CSF (TSC-G) activated dendritic cell- and T cell-mediated immune responses. In addition, our strategy exhibited greater therapeutic efficacy when compared with the existing oncolytic viral therapeutic approaches. Moreover, the TSCs composed of SC-oHSV and SCN1KO-releasing GM-CSF and single-chain variable fragment anti-PD-1 (TSC-G/P) had therapeutic efficacy in both syngeneic and patient-derived humanized mouse models of leptomeningeal metastasis. Our findings provide a promising allogeneic SC-based immunotherapeutic strategy against melanomas in the CNS and a road map toward clinical translation.

Clinical features of biliary tract cancer in Japanese individuals with Lynch syndrome.

Background: Biliary tract cancer (BTC) is a Lynch syndrome (LS)-associated cancer with a high mortality rate. This study aimed to clarify the clinical features of BTC in individuals with LS and to discuss its management. Methods: We obtained data from genetically verified Japanese individuals with LS who were diagnosed at a single institution, between January 2003 and April 2021. Moreover, 21 individuals with sporadic BTC (n=15) and LS associated BTC (n=6) underwent microsatellite instability (MSI) testing. Results: Among 92 individuals with LS, 6 individuals with MLH1 variants developed BTCs (10 lesions, male/female, 2:1). The median age at diagnosis of initial BTC was 69 years (range, 34-78 years). Histological examination revealed a predominance of differentiated adenocarcinoma (89%). Then, 2 individuals had multiple BTCs. All available 7 BTC lesions showed high-frequency of microsatellite instability (MSI-H). MLH1 carriers showed a 7.2% cumulative risk of BTC development at an age of 70 years. Five of the six individuals died of BTC. Conclusions: MSI analysis could facilitate LS identification in individuals with BTC. Surveillance for BTC should be considered for MLH1 carriers in Japan.

Oncolytic virus-mediated p53 overexpression promotes immunogenic cell death and efficacy of PD-1 blockade in pancreatic cancer.

Immune checkpoint inhibitors, including anti-programmed cell death 1 (PD-1) antibody, provide improved clinical outcome in certain cancers. However, pancreatic ductal adenocarcinoma (PDAC) is refractory to PD-1 blockade therapy due to poor immune response. Oncolytic virotherapy is a novel approach for inducing immunogenic cell death (ICD). We demonstrated the therapeutic potential of p53-expressing telomerase-specific oncolytic adenovirus OBP-702 to induce ICD and anti-tumor immune responses in human PDAC cells with different p53 status (Capan-2, PK-59, PK-45H, Capan-1, MIA PaCa-2, BxPC-3) and murine PDAC cells (PAN02). OBP-702 significantly enhanced ICD with secretion of extracellular adenosine triphosphate and high-mobility group box protein B1 by inducing p53-mediated apoptosis and autophagy. OBP-702 significantly promoted the tumor infiltration of CD8+ T cells and the anti-tumor efficacy of PD-1 blockade in a subcutaneous PAN02 syngeneic tumor model. Our results suggest that oncolytic adenovirus-mediated p53 overexpression augments ICD and the efficacy of PD-1 blockade therapy against cold PDAC tumors. Further in vivo experiments would be warranted to evaluate the survival benefit of tumor-bearing mice in combination therapy with OBP-702 and PD-1 blockade.