Dendritic cells (DCs) are the most potent antigen-presenting cells, and tumor antigen-loaded DCs (DC-vaccines) can activate tumor-specific cytotoxic T lymphocytes (CTLs) in lymphatic tissues. DC vaccination is a newly emerging and potent form of cancer immunotherapy and has clinically relevant mechanisms of action with great potential for the systemic treatment of cancers. However, clinical trials have demonstrated relatively poor therapeutic efficacy. The efficacy of DC-vaccines is strongly influenced by various techniques for the priming antigen loading onto DCs and their ability to migrate to the draining lymph nodes (LNs). Therefore, it is critical to improve DC-vaccines homing to draining LNs after administration in order to optimize DC-based therapy for individual patients. This review underlines 1) appropriate strategy to load tumor antigens onto DCs and 2) to optimize vaccine administration methods to ensure loaded DCs can migrate to LNs, in particular, Intraperitoneal (IP) injection. IP injection of DC-based vaccine may be a potential regimen for gastrointestinal tumors including hepatocellular carcinoma (HCC) and pancreatic adenocarcinoma (PDAC) since huge populations of LNs are present throughout the gastrointestinal track. Which might improve the subsequent migration to LNs.

It is unknown whether the route of administration impacts dendritic cell (DC)-based immunotherapy for pancreatic ductal adenocarcinoma (PDAC). We compared the effect of intraperitoneal (i.p.), subcutaneous (s.c.), and intratumoral (i.t.) administration of DC vaccine on induction of antitumor responses in a KPC mouse model of PDAC. Histological analysis and flow cytometry were used to evaluate tumor progression and antitumor immunity after different routes of DC vaccination. Using a flank mouse model of PDAC, we found that the i.t. route of DC vaccination had no significant effect on tumor growth rates compared with i.p. and s.c. routes (i.p. 6.66 ± 2.58% vs s.c. 6.79 ± 1.36% vs i.t. 8.57 ± 2.36%; P = 0.33). However, in an orthotopic PDAC model, i.p. injection of DC vaccine effectively suppressed tumor growth, inhibited tumor progression, and increased antitumor immunity compared with s.c. vaccination (tumor weight: i.p. 71.60 ± 15.55 mg vs control 200.40 ± 53.04 mg; P = 0.048; s.c. 151.40 ± 41.64 mg vs control 200.40 ± 53.04 mg; P = 0.49). Our study suggests that immunization via an i.p. route results in superior antitumor immune response and tumor suppression when compared with other routes.

Pancreatic ductal adenocarcinoma (PDAC) is associated with highly immunosuppressive tumor microenvironment (TME) that can limit the efficacy of dendritic cell (DC) vaccine immunotherapy. Irreversible electroporation (IRE) is a local ablation approach. Herein, we test the hypothesis that IRE ablation can overcome TME immunosuppression to improve the efficacy of DC vaccination using Kras^LSL-G12D-p53^LSL-R172H-Pdx-1-Cre (KPC) orthotopic mouse model of PDAC. The median survival for mice treated with the combined IRE and DC vaccination was 77 days compared with sham control (35 days), DC vaccination (49 days), and IRE (44 days) groups (P = .006). Thirty-six percent of the mice treated with combination IRE and DC vaccination were still survival at the end of the study period (90 days) without visible tumor. The changes of tumor apparent diffusion coefficient (ΔADC) were higher in mice treated with combination IRE and DC vaccination than that of other groups (all P < .001); tumor ΔADC value positively correlated with tumor fibrosis fraction (R = 0.707, P < .001). IRE induced immunogenic cell death and alleviation of immunosuppressive components in PDAC TME when combined with DC vaccination, including increased tumor infiltration of CD8⁺ T cells and Granzyme B⁺ cells (P = .001, and P = .007, respectively). Our data show that IRE ablation can overcome TME immunosuppression to improve the efficacy of DC vaccination in PDAC. Combination IRE ablation and DC vaccination may enhance therapeutic efficacy for PDAC.

Natural killer (NK) cells play a pivotal role in host immunity against different malignancies, including pancreatic ductal adenocarcinoma (PDAC). Our study aimed to evaluate the antitumor effects of NK cell-based adoptive transfer immunotherapy for PDAC in an orthotopic mouse model. Orthotopic KrasLSL-G12D p53LSL-R172H Pdx1-Cre (KPC) mice were used to evaluate the therapeutic efficacy. Mouse NK cells (LNK cells) (1×106) were intravenously injected to tumor-bearing mice once a week for 3 weeks. MRI measurements (tumor volume and apparent diffusion coefficient (ADC) values) and survival were compared between control and LNK treated tumors. Flow cytometry and enzyme-linked immunosorbent assay (ELISA) were used to determine LNK cells cytotoxicity and IFN-γ level, respectively. LNK cells can produce a higher level of IFN-γ and more effectively lyse PDAC cells compared with spleen NK cells in vitro. LNK-cell adoptive transfer therapy elicited potent in vivo antitumor activity, resulting in delayed tumor growth (P=0.033) in KPC mice. The ADC values at the last timepoint ((0.94±0.06)×10-3 mm2/s) were significantly higher than that at first timepoint ((0.75±0.04)×10-3 mm2/s) in treated tumors (P<0.001). ADC values were significantly different between control group and treated tumors at the last time point ((0.75±0.09)×10-3 mm2/s vs (0.94±0.06)×10-3 mm2/s, P=0.004) in KPC mice. Our data demonstrate the potential of NK cell-based adoptive transfer immunotherapy for PDAC treatment.

Dinaciclib is a small molecule cyclin-dependent kinase inhibitor with the potential to treat multiple cancers. To better understand its cytotoxic action in pancreatic ductal adenocarcinoma (PDAC), we evaluated dinaciclib therapeutic effects in the transgenic mouse model (LSL-KrasG12D/+ ; LSL-Trp53R172H/+ ; Pdx-1-Cre mice; KPC mice). Tumor growth and microenvironment were dynamically monitored by magnetic resonance imaging (MRI). Dinaciclib therapy significantly delayed tumor progression (P < 0.001) and prolonged survival (P = 0.007) in KPC mice. In vitro assays showed that dinaciclib exerted antiproliferative effects on PDAC cells by increasing surface calreticulin expression and release of ATP. Dinaciclib treatment inhibited proliferation and induced apoptosis in KPC tumor as assessed by Ki67 and cleaved caspase 3, respectively. Particularly, the tumor infiltrating CD8+ T cells were increased after dinaciclib treatment in KPC mice. Additionally, the mean apparent diffusion coefficient values of KPC tumor calculated from diffusion weighted MR images were significantly lower after dinaciclib treatment (P = 0.033). These finding suggest that dinaciclib as a single agent can inhibit tumor growth and improve the overall survival in KPC mice.

Background

Previous studies have shown the poor prognosis of metastatic breast cancer including bone metastasis. The early prediction and intervention of invasive breast carcinoma with bone metastasis are crucial to the outcomes of patients. The purpose of our study is to test the hypothesis that the collagen deposition of primary breast cancer can be used as a quantitative biomarker for the early prediction of bone metastasis.

Methods

A total of sixty breast cancer patients were included in our study, and the surgical specimens of these patients were divided into three groups: patients with no metastasis (group 1), lymph node metastasis (group 2), and bone metastasis (group 3). Masson's trichrome staining and hematoxylin and eosin staining were applied to all primary breast cancers. Collagen area percentage and tumor cell measurement of each sample were measured by HistoQuest software.

Results

Measurement results of collagen area percentage (%) in primary breast tumors were 32.39 ± 13.30, 25.37 ± 11.10, and 22.71 ± 8.91 for groups 1, 2, and 3, respectively. The corresponding P values were 0.0779 (group 1 vs. group 2), 0.4086 (group 2 vs. group 3), and 0.0102 (group 1 vs. group 3). The correlation between collagen area percentage and tumor cell measurement were group 1 (P = 0.5927, r = -0.1273), group 2 (P = 0.5711, r = -0.1348), and group 3 (P = 0.0003, r = -0.7253).

Conclusions

The collagen deposition of primary breast cancer can be used as a quantitative biomarker for the early prediction of bone metastasis.

Dendritic cell (DC) based immunotherapy is a promising approach for cancer treatment and has been approved in clinical settings for decades. Clinical trials have demonstrated relatively poor therapeutic efficacy. The efficacy of DC immunotherapy is strongly influenced by their ability to migrate to the draining lymph nodes (LNs). Therefore, it is critical to deliver DCs and monitor the in vivo biodistributions of DCs after administration. The purpose of this study is to determine whether a novel injection route of DCs improves DC migration to LNs, tissues, organs and lymphatics. In the present study, a modified method was investigated to acquire DCs from mouse bone marrow. Cultured antibody labeled DCs were analyzed by flow cytometry. India ink was used to visualize mouse abdominal LNs and PKH26 was utilized to label DCs for intraperitoneal (IP) injection, results were evaluated by histology. Our results showed that large amounts of DCs with a relatively high purity were acquired. IP injection of india ink marked the abdominal LNs and PKH26 labeled DCs showed IP was an effective administration route to increase the absorption of viable DCs, and different time points after IP inject showed no significant difference of the migrated DCs. The findings indicated that large amounts of high purity DCs can be acquired through our method and IP injection accelerates DCs migration to abdominal LNs, which can be directly translated to clinical settings, especially for abdominal cancers. This study makes a foundation for future researches of DC-based immunotherapy as a treatment modality against cancer.

In recent decades, immunotherapy has undergone extensive developments for oncologic therapy applications. Dendritic cells (DCs) plays a fundamental role in cell-based vaccination immunotherapy against various types of cancer. It involves stimulating innate and adaptive immunity, in particular cytotoxic T-cell mediated antitumor effects, against targeted tumors and has been studied in both preclinical and clinical settings. Nevertheless, clinical outcomes have been unsatisfying. The antitumor response requires sufficient migration of viable DCs from primary administration site to targeted tumors through related lymphatics. The dynamics and mechanisms of the DCs migration still need further investigation. Here, we briefly introduce the current clinically applicable methods for manufacturing DC-based cancer vaccines and their most commonly used non-invasive, real-time tracking approaches. Furthermore, we propose a hypothesis that intraperitoneal injection may improve the efficiency of DC-based cancer vaccine.

The purpose of our study was to investigate the hypothesis that DWI-MRI and DCE-MRI cab be used to distinguish between IRE and RE zones of IRE treatment in a rabbit liver model. 6 rabbits underwent baseline and post-procedure MR imaging with DWI and DCE-MRI as well as IRE (10 pulses, 2000 V, 10 µs/pulse, 10 ms between pulses). Rabbits were euthanized immediately after post-procedure MRI to acquire liver tissue for histology. Liver tissues were fixed and then stained with HE and TUNEL. T1w and T2w intensities in different treatment zones were calculated and normalized to paraspinal muscle signal. ADC maps were generated from DWI. AUC, PE, TTP, WIS, K_trans, K_ep, and V_E were calculated from DCE-MRI. Apoptosis index was calculated from TUNEL stained tissues. P<0.05 was considered statistically significant. Entire IRE treated region was hyperintense compared with untreated tissues on T1w, with the RE zone having a higher signal intensity. On DWI, IRE treated tissue had decreased ΔADC. The IRE zone has a lower ΔADC than the RE zone within the treated region. On DCE-MRI, IRE zone demonstrated the highest TTP and the lowest PE, WIS, K_trans, K_ep, and V_E, followed by the RE zone then the untreated tissue. TUNEL staining of liver tissues showed that the IRE zone had the highest apoptosis index, followed by the RE zone and then untreated tissue. In conclusion, DCE-MRI and DWI parameters allow differentiation between RE and IRE zones in a rabbit liver model.

The promise of dendritic cell (DC)-based immunotherapy has been established by two decades of translational research. However, long-term benefits of DC vaccination are reported in only scattered patients with pancreatic ductal adenocarcinoma (PDAC). Here we optimize DC vaccination and evaluate its safety and antitumor efficacy in the genetically engineered PDAC model (Kras^LSL-G12D p53^LSL-R172H Pdx-1-Cre (KPC mice)). KPC transgenic mice and orthotopic models using KPC cell lines were treated with DC vaccine via an intraperitoneal route. Tumor growth and microenvironment were dynamically monitored by magnetic resonance imaging (MRI). Histological analysis and flow cytometry were used to evaluate tumor-directed T cell immunity of these mice. DC vaccine via intraperitoneal injection suppressed tumor progression (P = 0.030) and significantly prolonged survival time (P = 0.028) in KPC mice. Vaccinated KPC mice displayed an increased antitumor T cell response indicated by a higher IFN-γ production (P = 0.016) and tumor-specific cytotoxicity (P = 0.027). Particularly, the mean apparent diffusion coefficient (ADC) values of KPC tumor calculated from diffusion weighted MRI (DW-MRI) were significantly higher in DC vaccine group than that in control group (P < 0.001). More interestingly, we observed that ADC positively correlated with fibrosis in KPC tumor (R² = 0.463, P = 0.015). Our study demonstrated that the immunization with our improved DC vaccine can elicit a strong tumor-specific immune response and tumor suppression in PDAC.