Functional remodeling of intraperitoneal macrophages by oncolytic adenovirus restores anti-tumor immunity for peritoneal metastasis of gastric cancer.

Intraperitoneal tumor-associated macrophages (TAMs) are involved in evading anti-tumor immunity and promoting the peritoneal metastasis (PM) of gastric cancer (GC). Oncolytic viruses are known to induce the activation of host anti-tumor immunity in addition to tumor lysis. This study investigated whether a wild-type p53-loading telomerase-specific oncolytic adenovirus (OBP-702) could elicit the remodeling of intraperitoneal macrophages and enhance the efficacy of immune therapy. Increased numbers of CD163 TAMs and few CD8+ lymphocytes were immunohistochemically observed in clinical samples with PM, which suggested that TAMs were associated with the suppression of anti-tumor immunity. OBP-702 induced immunogenic cell death and upregulated PD-L1 expression in human and murine GC cell lines. Intraperitoneal administration of OBP-702 increased recruitment of CD8+ lymphocytes into the PM via the functional remodeling of intraperitoneal macrophages from TAM toward a pro-inflammatory phenotype, resulting in significantly suppressed tumor growth for the in vivo model. Furthermore, the combination of intraperitoneal OBP-702 with anti-programmed cell death-1 antibody enhanced anti-tumor immunity and prolonged the survival of mice bearing PM. Intraperitoneal immunotherapy using OBP-702 restores anti-tumor immunity via the remodeling of intraperitoneal macrophages in addition to direct tumor lysis and cooperates with immune checkpoint inhibitors to suppress PM in GC.

Near-infrared Photoimmunotherapy Targeting Cancer-Associated Fibroblasts in Patient-Derived Xenografts using a Humanized anti-Fibroblast Activation Protein Antibody.

Esophageal cancer remains a highly aggressive malignancy with a poor prognosis, despite ongoing advancements in treatments such as immunotherapy. The tumor microenvironment, particularly cancer-associated fibroblasts (CAFs), plays a crucial role in driving the aggressiveness of esophageal cancer. In a previous study utilizing human-derived xenograft models, we successfully developed a novel cancer treatment that targeted CAFs with near-infrared photoimmunotherapy (NIR-PIT), as an adjuvant therapy. In this study, we sought to translate our findings toward clinical practice by employing patient-derived xenograft (PDX) models and utilizing humanized monoclonal antibodies, specifically Sibrotuzumab, which is anti-human fibroblast activation protein (FAP) antibody and already being investigated in clinical trials as monotherapy. PDX models derived from esophageal cancer patients were effectively established, preserving the expression of key biomarkers such as EGFR and FAP, as observed in primary tumors. The application of FAP-targeted NIR-PIT using Sibrotuzumab, conjugated with the photosensitizer IR700DX, exhibited precise binding and selective elimination of FAP-expressing fibroblasts in vitro. Notably, in our in vivo investigations using both cell line-derived xenograft and PDX models, FAP-targeted NIR-PIT led to significant inhibition of tumor progression compared to control groups, all without inducing adverse events such as weight loss. Immunohistological assessments revealed a substantial reduction in CAFs exclusively within the tumor microenvironment of both models, further supporting the efficacy of our approach. Thus, our study demonstrates the potential of CAF-targeted NIR-PIT employing Sibrotuzumab as a promising therapeutic avenue for clinical treatment of esophageal cancer patients.

p53-Armed Oncolytic Virotherapy Improves Radiosensitivity in Soft-Tissue Sarcoma by Suppressing BCL-xL Expression.

Soft-tissue sarcoma (STS) is a heterogeneous group of rare tumors originating predominantly from the embryonic mesoderm. Despite the development of combined modalities including radiotherapy, STSs are often refractory to antitumor modalities, and novel strategies that improve the prognosis of STS patients are needed. We previously demonstrated the therapeutic potential of two telomerase-specific replication-competent oncolytic adenoviruses, OBP-301 and tumor suppressor p53-armed OBP-702, in human STS cells. Here, we demonstrate in vitro and in vivo antitumor effects of OBP-702 in combination with ionizing radiation against human STS cells (HT1080, NMS-2, SYO-1). OBP-702 synergistically promoted the antitumor effect of ionizing radiation in the STS cells by suppressing the expression of B-cell lymphoma-X large (BCL-xL) and enhancing ionizing radiation-induced apoptosis. The in vivo experiments demonstrated that this combination therapy significantly suppressed STS tumors' growth. Our results suggest that OBP-702 is a promising antitumor reagent for promoting the radiosensitivity of STS tumors.

Fibroblast activation protein-targeted near-infrared photoimmunotherapy depletes immunosuppressive cancer-associated fibroblasts and remodels local tumor immunity.

BACKGROUND: Cancer-associated fibroblasts (CAFs) in the tumor microenvironment (TME) play a critical role in tumor immunosuppression. However, targeted depletion of CAFs is difficult due to their diverse cells of origin and the resulting lack of specific surface markers. Near-infrared photoimmunotherapy (NIR-PIT) is a novel cancer treatment that leads to rapid cell membrane damage. METHODS: In this study, we used anti-mouse fibroblast activation protein (FAP) antibody to target FAP+ CAFs (FAP-targeted NIR-PIT) and investigated whether this therapy could suppress tumor progression and improve tumor immunity. RESULTS: FAP-targeted NIR-PIT induced specific cell death in CAFs without damaging adjacent normal cells. Furthermore, FAP-targeted NIR-PIT treated mice showed significant tumor regression in the CAF-rich tumor model accompanied by an increase in CD8+ tumor infiltrating lymphocytes (TILs). Moreover, treated tumors showed increased levels of IFN-γ, TNF-α, and IL-2 in CD8+ TILs compared with non-treated tumors, suggesting enhanced antitumor immunity. CONCLUSIONS: Cancers with FAP-positive CAFs in their TME grow rapidly and FAP-targeted NIR-PIT not only suppresses their growth but improves tumor immunosuppression. Thus, FAP-targeted NIR-PIT is a potential therapeutic strategy for selectively targeting the TME of CAF+ tumors.

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.

Fluorescence-guided assessment of bone and soft-tissue sarcomas for predicting the efficacy of telomerase-specific oncolytic adenovirus.

Bone and soft-tissue sarcomas are rare malignancies with histological diversity and tumor heterogeneity, leading to the lack of a common molecular target. Telomerase is a key enzyme for keeping the telomere length and human telomerase reverse transcriptase (hTERT) expression is often activated in most human cancers, including bone and soft-tissue sarcomas. For targeting of telomerase-positive tumor cells, we developed OBP-301, a telomerase-specific replication-competent oncolytic adenovirus, in which the hTERT promoter regulates adenoviral E1 gene for tumor-specific viral replication. In this study, we present the diagnostic potential of green fluorescent protein (GFP)-expressing oncolytic adenovirus OBP-401 for assessing virotherapy sensitivity using bone and soft-tissue sarcomas. OBP-401-mediated GFP expression was significantly associated with the therapeutic efficacy of OBP-401 in human bone and soft-tissue sarcomas. In the tumor specimens from 68 patients, malignant and intermediate tumors demonstrated significantly higher expression levels of coxsackie and adenovirus receptor (CAR) and hTERT than benign tumors. OBP-401-mediated GFP expression was significantly increased in malignant and intermediate tumors with high expression levels of CAR and hTERT between 24 and 48 h after infection. Our results suggest that the OBP-401-based GFP expression system is a useful tool for predicting the therapeutic efficacy of oncolytic virotherapy on bone and soft-tissue sarcomas.

Intraperitoneal Administration of p53-armed Oncolytic Adenovirus Inhibits Peritoneal Metastasis of Diffuse-type Gastric Cancer Cells.

BACKGROUND/AIM: Diffuse-type gastric cancer (GC) frequently exhibits peritoneal metastasis, leading to poor prognosis. However, efforts to develop antitumor strategies for preventing the peritoneal metastasis of GC have been unsuccessful. As diffuse-type GC cells often carry a genetic alteration in the tumor suppressor p53 gene, p53 restoration may be a potent strategy for preventing peritoneal metastasis of GC. In this study, we investigated the therapeutic potential of p53-expressing adenoviral vectors against peritoneal metastasis of diffuse-type GC cells. MATERIALS AND METHODS: Three diffuse-type human GC cell types with different p53 statuses (p53-wild type NUGC-4, p53-mutant type GCIY, and p53-null type KATOIII) were used to evaluate the therapeutic potential of p53 activation induced by the p53-expressing, replication-deficient adenovirus Ad-p53 and oncolytic adenovirus OBP-702. Viability, apoptosis, and autophagy of virus-treated GC cells were analyzed under normal and sphere-forming culture conditions using the XTT assay and western blot analysis. The in vivo antitumor effects of OBP-702 and Ad-p53 were assessed using xenograft tumor models involving peritoneal metastasis of NUGC-4 and GCIY cells. RESULTS: Under normal and sphere-forming culture conditions, OBP-702 induced a significantly greater antitumor effect in GC cells compared with Ad-p53 by strongly inducing p53-mediated apoptosis and autophagy and receptor tyrosine kinase suppression. In vivo experiments demonstrated that intraperitoneal administration of OBP-702 significantly suppressed the peritoneal metastasis of NUGC-4 and GCIY cells compared with Ad-p53, leading to prolonged survival of mice. CONCLUSION: Intraperitoneal administration of OBP-702 inhibits the peritoneal metastasis of GC cells by inducing p53-mediated cytopathic activity.

[Therapeutic Effect of Oncolytic Adenovirus on Pancreatic Cancer Stroma].

Pancreatic ductal adenocarcinoma(PDAC)is lethal malignancy with abundant stroma. Cancer-associated fibroblasts (CAFs) exist in the PDAC stroma and contribute to progression of malignant transformation, treatment resistance, and recurrence. However, effective treatment to control PDAC stroma has not been established. We have developed tumor suppressor gene p53-armed oncolytic adenovirus(OBP-702), and have clarified therapeutic effects on PDAC cells. In this study, we investigate the therapeutic effect of OBP-702 on PDAC CAF.

p53-armed oncolytic adenovirus induces autophagy and apoptosis in KRAS and BRAF-mutant colorectal cancer cells.

Colorectal cancer (CRC) cells harboring KRAS or BRAF mutations show a more-malignant phenotype than cells with wild-type KRAS and BRAF. KRAS/BRAF-wild-type CRCs are sensitive to epidermal growth factor receptor (EGFR)-targeting agents, whereas KRAS/BRAF-mutant CRCs are resistant due to constitutive activation of the EGFR-downstream KRAS/BRAF signaling pathway. Novel therapeutic strategies to treat KRAS/BRAF mutant CRC cells are thus needed. We recently demonstrated that the telomerase-specific replication-competent oncolytic adenoviruses OBP-301 and p53-armed OBP-702 exhibit therapeutic potential against KRAS-mutant human pancreatic cancer cells. In this study, we evaluated the therapeutic potential of OBP-301 and OBP-702 against human CRC cells with differing KRAS/BRAF status. Human CRC cells with wild-type KRAS/BRAF (SW48, Colo320DM, CACO-2), mutant KRAS (DLD-1, SW620, HCT116), and mutant BRAF (RKO, HT29, COLO205) were used in this study. The antitumor effect of OBP-301 and OBP-702 against CRC cells was analyzed using the XTT assay. Virus-mediated modulation of apoptosis, autophagy, and the EGFR-MEK-ERK and AKT-mTOR signaling pathways was analyzed by Western blotting. Wild-type and KRAS-mutant CRC cells were sensitive to OBP-301 and OBP-702, whereas BRAF-mutant CRC cells were sensitive to OBP-702 but resistant to OBP-301. Western blot analysis demonstrated that OBP-301 induced autophagy and that OBP-702 induced autophagy and apoptosis in human CRC cells. In BRAF-mutant CRC cells, OBP-301 and OBP-702 suppressed the expression of EGFR, MEK, ERK, and AKT proteins, whereas mTOR expression was suppressed only by OBP-702. Our results suggest that p53-armed oncolytic virotherapy is a viable therapeutic option for treating KRAS/BRAF-mutant CRC cells via induction of autophagy and apoptosis.

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.

PD-L1-expressing cancer-associated fibroblasts induce tumor immunosuppression and contribute to poor clinical outcome in esophageal cancer.

The programmed cell death 1 protein (PD-1)/programmed cell death ligand 1 (PD-L1) axis plays a crucial role in tumor immunosuppression, while the cancer-associated fibroblasts (CAFs) have various tumor-promoting functions. To determine the advantage of immunotherapy, the relationship between the cancer cells and the CAFs was evaluated in terms of the PD-1/PD-L1 axis. Overall, 140 cases of esophageal cancer underwent an immunohistochemical analysis of the PD-L1 expression and its association with the expression of the α smooth muscle actin, fibroblast activation protein, CD8, and forkhead box P3 (FoxP3) positive cells. The relationship between the cancer cells and the CAFs was evaluated in vitro, and the effect of the anti-PD-L1 antibody was evaluated using a syngeneic mouse model. A survival analysis showed that the PD-L1+ CAF group had worse survival than the PD-L1- group. In vitro and in vivo, direct interaction between the cancer cells and the CAFs showed a mutually upregulated PD-L1 expression. In vivo, the anti-PD-L1 antibody increased the number of dead CAFs and cancer cells, resulting in increased CD8+ T cells and decreased FoxP3+ regulatory T cells. We demonstrated that the PD-L1-expressing CAFs lead to poor outcomes in patients with esophageal cancer. The cancer cells and the CAFs mutually enhanced the PD-L1 expression and induced tumor immunosuppression. Therefore, the PD-L1-expressing CAFs may be good targets for cancer therapy, inhibiting tumor progression and improving host tumor immunity.

Dual antiplatelet therapy inhibits neutrophil extracellular traps to reduce liver micrometastases of intrahepatic cholangiocarcinoma.

The involvement of neutrophil extracellular traps (NETs) in cancer metastasis is being clarified, but the relationship between intrahepatic cholangiocarcinoma (iCCA) and NETs remains unclear. The presence of NETs was verified by multiple fluorescence staining in clinically resected specimens of iCCA. Human neutrophils were co-cultured with iCCA cells to observe NET induction and changes in cellular characteristics. Binding of platelets to iCCA cells and its mechanism were also examined, and their effects on NETs were analyzed in vitro and in in vivo mouse models. NETs were present in the tumor periphery of resected iCCAs. NETs promoted the motility and migration ability of iCCA cells in vitro. Although iCCA cells alone had a weak NET-inducing ability, the binding of platelets to iCCA cells via P-selectin promoted NET induction. Based on these results, antiplatelet drugs were applied to these cocultures in vitro and inhibited the binding of platelets to iCCA cells and the induction of NETs. Fluorescently labeled iCCA cells were injected into the spleen of mice, resulting in the formation of liver micrometastases coexisting with platelets and NETs. These mice were treated with dual antiplatelet therapy (DAPT) consisting of aspirin and ticagrelor, which dramatically reduced micrometastases. These results suggest that potent antiplatelet therapy prevents micrometastases of iCCA cells by inhibiting platelet activation and NET production, and it may contribute to a novel therapeutic strategy.

Conventional Cancer Therapies Can Accelerate Malignant Potential of Cancer Cells by Activating Cancer-Associated Fibroblasts in Esophageal Cancer Models.

Esophageal cancer is one of the most aggressive tumors, and the outcome remains poor. One contributing factor is the presence of tumors that are less responsive or have increased malignancy when treated with conventional chemotherapy, radiotherapy, or a combination of these. Cancer-associated fibroblasts (CAFs) play an important role in the tumor microenvironment. Focusing on conventional cancer therapies, we investigated how CAFs acquire therapeutic resistance and how they affect tumor malignancy. In this study, low-dose chemotherapy or radiotherapy-induced normal fibroblasts showed enhanced activation of CAFs markers, fibroblast activation protein, and α-smooth muscle actin, indicating the acquisition of malignancy in fibroblasts. Furthermore, CAFs activated by radiotherapy induce phenotypic changes in cancer cells, increasing their proliferation, migration, and invasion abilities. In in vivo peritoneal dissemination models, the total number of tumor nodules in the abdominal cavity was significantly increased in the co-inoculation group of cancer cells and resistant fibroblasts compared to that in the co-inoculation group of cancer cells and normal fibroblasts. In conclusion, we demonstrated that conventional cancer therapy causes anti-therapeutic effects via the activation of fibroblasts, resulting in CAFs. It is important to select or combine modalities of esophageal cancer treatment, recognizing that inappropriate radiotherapy and chemotherapy can lead to resistance in CAF-rich tumors.

Current Femoral Stem Fixation Selection in Hip-Fracture Bipolar Hemiarthroplasties, and Factors Affecting Surgeons' Confidence in Their Ability to Teach about Cemented Stems: A Questionnaire in a Region of Japan with Super-Aged Patients.

Japan's hip fracture management guidelines now recommend the use of cemented stems in cases of bone fragility. However, the current stem selection practices in bipolar hemiarthroplasty (BHA) in a super-aging area in Japan remain unclear. This study aimed to examine the stem selection policies, the surgeons' concerns about cemented stems, and factors affecting their confidence in their ability to coach others on cemented stem procedures. Ninety-four orthopedic surgeons (27 facilities) responded to our web-based questionnaire conducted in January/February 2022. Cementless stem was the first choice of 97.8% of the surgeons; <15% of the respondents expected to increase their use of cemented stems in the future. The cement technique was the greatest concern; almost half of the surgeons described having insufficient experience with cemented stems. The factor that most affected the surgeons' expertise in using cemented stems is the number of surgeries they had conducted with a cemented stem (multivariable analysis odds ratio 8.42, p=0.001). Greater experience was associated with increased expertise of the surgeons in using cemented stems, with a threshold of 11 cases showing sensitivity of 41.7% and specificity of 98.3% for their confidence to instruct cemented stems.

Overcoming cancer-associated fibroblast-induced immunosuppression by anti-interleukin-6 receptor antibody.

Cancer-associated fibroblasts (CAFs) are a critical component of the tumor microenvironment and play a central role in tumor progression. Previously, we reported that CAFs might induce tumor immunosuppression via interleukin-6 (IL-6) and promote tumor progression by blocking local IL-6 in the tumor microenvironment with neutralizing antibody. Here, we explore whether an anti-IL-6 receptor antibody could be used as systemic therapy to treat cancer, and further investigate the mechanisms by which IL-6 induces tumor immunosuppression. In clinical samples, IL-6 expression was significantly correlated with α-smooth muscle actin expression, and high IL-6 cases showed tumor immunosuppression. Multivariate analysis showed that IL-6 expression was an independent prognostic factor. In vitro, IL-6 contributed to cell proliferation and differentiation into CAFs. Moreover, IL-6 increased hypoxia-inducible factor 1α (HIF1α) expression and induced tumor immunosuppression by enhancing glucose uptake by cancer cells and competing for glucose with immune cells. MR16-1, a rodent analog of anti-IL-6 receptor antibody, overcame CAF-induced immunosuppression and suppressed tumor progression in immunocompetent murine cancer models by regulating HIF1α activation in vivo. The anti-IL-6 receptor antibody could be systemically employed to overcome tumor immunosuppression and improve patient survival with various cancers. Furthermore, the tumor immunosuppression was suggested to be induced by IL-6 via HIF1α activation.

ADAR1 is a promising risk stratification biomarker of remnant liver recurrence after hepatic metastasectomy for colorectal cancer.

Adenosine-to-inosine RNA editing is a process mediated by adenosine deaminases that act on the RNA (ADAR) gene family. It has been discovered recently as an epigenetic modification dysregulated in human cancers. However, the clinical significance of RNA editing in patients with liver metastasis from colorectal cancer (CRC) remains unclear. The current study aimed to systematically and comprehensively investigate the significance of adenosine deaminase acting on RNA 1 (ADAR1) expression status in 83 liver metastatic tissue samples collected from 36 patients with CRC. The ADAR1 expression level was significantly elevated in liver metastatic tissue samples obtained from patients with right-sided, synchronous, or RAS mutant-type CRC. ADAR1-high liver metastasis was significantly correlated with remnant liver recurrence after hepatic metastasectomy. A high ADAR1 expression was a predictive factor of remnant liver recurrence (area under the curve = 0.72). Results showed that the ADAR1 expression level could be a clinically relevant predictive indicator of remnant liver recurrence. Patients with liver metastases who have a high ADAR1 expression requires adjuvant chemotherapy after hepatic metastasectomy.

RNA Editing is a Valuable Biomarker for Predicting Carcinogenesis in Ulcerative Colitis.

BACKGROUND AND AIMS: Ulcerative colitis [UC] can lead to colitis-associated colorectal neoplasm [CAN]. Adenosine-to-inosine RNA editing, which is regulated by adenosine deaminase acting on RNA [ADAR], induces the post-transcriptional modification of critical oncogenes, including antizyme inhibitor 1 [AZIN1], leading to colorectal carcinogenesis. Therefore, we hypothesized that ADAR1 might be involved in the development of CAN in UC. METHODS: We systematically analysed a cohort of 139 UC cases [40 acute phase, 73 remission phase, 26 CAN]. The degree of inflammation was evaluated using the Mayo endoscopic score [MES]. RESULTS: The type 1 interferon [IFN]-related inflammation pathway was upregulated in the rectum of active UC, rectum of UC-CAN and tumour site of UC-CAN patients. ADAR1 expression was upregulated in the entire colon of CAN cases, while it was downregulated in non-CAN MES0 cases. ADAR1 expression in the rectum predicted the development of CAN better than p53 or ß-catenin, with an area under the curve of 0.93. The high expression of ADAR1 and high AZIN1 RNA editing in UC was triggered by type 1 IFN stimulation from UC-specific microbiomes, such as seen in Fusobacterium in vitro analyses. The induction of AZIN1 RNA editing by ADAR1, whose expression is promoted by Fusobacterium, may induce carcinogenesis in UC. CONCLUSIONS: The risk of CAN can be evaluated by assessing ADAR1 expression in the rectum of MES0 UC patients, freeing UC patients from unnecessary colonoscopy and reducing their physical burden. RNA editing may be involved in UC carcinogenesis, and may be used to facilitate the prevention and treatment of CAN in UC.

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.

Dual-targeted near-infrared photoimmunotherapy for esophageal cancer and cancer-associated fibroblasts in the tumor microenvironment.

Cancer-associated fibroblasts (CAFs) play a significant role in tumor progression within the tumor microenvironment. Previously, we used near-infrared photoimmunotherapy (NIR-PIT), a next-generation cancer cell-targeted phototherapy, to establish CAF-targeted NIR-PIT. In this study, we investigated whether dual-targeted NIR-PIT, targeting cancer cells and CAFs, could be a therapeutic strategy. A total of 132 cases of esophageal cancer were analyzed for epidermal growth factor receptor (EGFR), human epidermal growth factor 2 (HER2), and fibroblast activation protein (FAP) expression using immunohistochemistry. Human esophageal cancer cells and CAFs were co-cultured and treated with single- or dual-targeted NIR-PIT in vitro. These cells were co-inoculated into BALB/c-nu/nu mice and the tumors were treated with single-targeted NIR-PIT or dual-targeted NIR-PIT in vivo. Survival analysis showed FAP- or EGFR-high patients had worse survival than patients with low expression of FAP or EGFR (log-rank, P < 0.001 and P = 0.074, respectively), while no difference was observed in HER2 status. In vitro, dual (EGFR/FAP)-targeted NIR-PIT induced specific therapeutic effects in cancer cells and CAFs along with suppressing tumor growth in vivo, whereas single-targeted NIR-PIT did not show any significance. Moreover, these experiments demonstrated that dual-targeted NIR-PIT could treat cancer cells and CAFs simultaneously with a single NIR light irradiation. We demonstrated the relationship between EGFR/FAP expression and prognosis of patients with esophageal cancer and the stronger therapeutic effect of dual-targeted NIR-PIT than single-targeted NIR-PIT in experimental models. Thus, dual-targeted NIR-PIT might be a promising therapeutic strategy for cancer treatment.

An oncolytic virus as a promising candidate for the treatment of radioresistant oral squamous cell carcinoma.

We evaluated the usefulness of an oncolytic virus (Suratadenoturev; OBP-301) against radioresistant oral squamous cell carcinoma. We confirmed the expression of human telomerase reverse transcriptase and the coxsackievirus and adenovirus receptor in cell lines. Also, we examined the potential presence in a patient who has received existing therapy that is amenable to treatment with OBP-301. We evaluated: (1) the antitumor effects of OBP-301 alone and in combination with radiotherapy on radioresistant cell lines, (2) the molecular mechanism underlying the radiosensitizing effect and cell death increased by the combination therapy, and (3) the antitumor effect of the combination therapy in vivo using xenograft models (a radioresistant cell line-derived xenograft in mouse and a patient-derived xenograft). Human telomerase reverse transcriptase and the coxsackievirus and adenovirus receptor were expressed in all cell lines. OBP-301 decreased the proliferative activity of these cell lines in a concentration-dependent manner, and significantly enhanced the antitumor effect of irradiation. Phosphorylated STAT3 and its downstream molecules, which correlated with apoptosis and autophagy, showed significant changes in expression after treatment with OBP-301. The combination therapy exerted a significant antitumor effect versus radiotherapy alone in both xenograft models. Combination of OBP-301 with radiotherapy exerts a synergistic effect and may represent a promising treatment for radioresistant oral squamous cell carcinoma.