White paper on microbial anti-cancer therapy and prevention.

In this White Paper, we discuss the current state of microbial cancer therapy. This paper resulted from a meeting ('Microbial Based Cancer Therapy') at the US National Cancer Institute in the summer of 2017. Here, we define 'Microbial Therapy' to include both oncolytic viral therapy and bacterial anticancer therapy. Both of these fields exploit tumor-specific infectious microbes to treat cancer, have similar mechanisms of action, and are facing similar challenges to commercialization. We designed this paper to nucleate this growing field of microbial therapeutics and increase interactions between researchers in it and related fields. The authors of this paper include many primary researchers in this field. In this paper, we discuss the potential, status and opportunities for microbial therapy as well as strategies attempted to date and important questions that need to be addressed. The main areas that we think will have the greatest impact are immune stimulation, control of efficacy, control of delivery, and safety. There is much excitement about the potential of this field to treat currently intractable cancer. Much of the potential exists because these therapies utilize unique mechanisms of action, difficult to achieve with other biological or small molecule drugs. By better understanding and controlling these mechanisms, we will create new therapies that will become integral components of cancer care.

Cryoablation and Meriva have strong therapeutic effect on triple-negative breast cancer.

Interleukin-6, a cytokine produced particularly by triple-negative breast cancers, strongly inhibits T cell responses in the tumor microenvironment. Here we tested cryoablation combined with Meriva (a lecithin delivery system of curcumin with improved bioavailability) in mice with metastatic breast cancer (4T1). Cryoablation involves killing of tumor cells through freezing and thawing, resulting in recruitment of tumor-specific T cells, while curcumin stimulates T cells through the reduction of IL-6 in the TME. Cryoablation plus Meriva accumulated and activated CD8+ T cells to multiple tumor-associated antigens such as Mage-b and Survivin (both expressed by 4T1 tumors). This correlated with a nearly complete reduction of 4T1 primary tumors and lung metastases while little effect was observed from saline or Meriva alone (28 d after tumor cell injection). The survival rate in the group of cryoablation plus Meriva was significantly improved compared to all control groups. Using a less aggressive 4T1 model expressing luciferase (4T1.2luc3), we demonstrated that all mice receiving saline or Meriva developed metastases in the lungs and a primary tumor (38 d after tumor cell injection; and died soon after that), but not the mice receiving cryoablation or cryoablation plus Meriva. However, on day 58 the mice receiving cryoablation developed 4T1.2luc3 metastases in the lungs, while mice receiving cryoablation plus Meriva were free of metastases. These results strongly suggest that cryoablation delayed the development of lung metastases on the short-term, but Meriva administered after cryoablation was significantly better in delaying the development of lung metastases and survival on the long-term.

In vitro and in vivo investigations on the antitumour activity of Chelidonium majus.

BACKGROUND: Chelidonium majus L. (Papaveraceae) (greater celandine) is a medicinal herb that is widely spread in Europe. Antitumoural activity has been reported for C. majus extracts. HYPOTHESIS/PURPOSE: To investigate the antitumour activity of a C. majus extract in vitro and in vivo. STUDY DESIGN: Cytotoxic effects of C. majus extracts were evaluated on human cancer cell lines, i.e. PANC-1 (pancreas cancer), HT-29 (colon cancer), MDA-MB-231 (breast cancer), PC-EM005 and PC-EM002 (primary endometrium cancer cells), and PANC02 (murine pancreatic adenocarcinoma cells). A preliminary in vivo study was performed to evaluate the effect of a defatted C. majus extract and Ukrain(TM) in a highly metastatic murine pancreatic model. METHODS: Chelidonium majus L. herb containing 1.26% (dry weight) of total alkaloids expressed as chelidonine was used to prepare an 80% ethanolic extract (CM2). This crude extract was then defatted with n-hexane, resulting in a defatted C. majus extract (CM2B). Cytotoxic effects of the two extracts (CM2 and CM2B) were evaluated on human and murine cell lines in vitro. CM2B and Ukrain(TM) were evaluated in a highly metastatic murine pancreatic model. RESULTS: Four main benzylisoquinoline alkaloids were identified in CM2B, i.e. chelidonine, sanguinarine, chelerythrine and protopine, using HPLC-UV. CM2 showed a high cytotoxic activity against PANC-1 (IC50, 20.7 µg/ml) and HT-29 (IC50, 20.6 µg/ml), and a moderate cytotoxic activity against MDA-MB-231 (IC50, 73.9 µg/ml). CM2 as well as CM2B showed a moderate to high cytotoxic activity against the PANC02 cell line (IC50, 34.4 and 36.0 µg/ml). Low to almost no cytotoxic effect was observed on primary endometrium cancer cells PC-EM005, PC-EM002 and on normal fibroblast cells 3T3, when treated with CM2B. Significantly less metastases were counted in mice treated with 1.2 mg/kg CM2B, but not with 3.6 mg/kg Ukrain(TM), compared to the control group. The extract, however, did not affect the weight of the primary tumours.

Characterization and assessment of nanoencapsulated sanguinarine chloride as a potential treatment for melanoma.

Sanguinarine has a history of use in both folk medicine and early dermatology for the treatment of cutaneous neoplasms. Applied indiscriminately, bloodroot is an escharotic agent with potential to cause extensive tissue necrosis. However, when used in a controlled fashion, sanguinarine imparts selective cytotoxic/anti-proliferative activity through multiple mechanisms against human/ murine melanoma. To exploit sanguinarine's observed activity against melanoma, a targeted delivery system is required. We present a sol-gel based nanoparticulate platform for encapsulating sanguinarine chloride(sang-np)-a targeted therapeutic capable of steady, reliable delivery of predictable quantities of drug over a sustained time period with minimal undesirable effects. Size and release kinetics of sang-np were characterized using dynamic light scattering and ultraviolet-visible spectroscopy respectively. In vitro efficacy of sang-np was assessed. At both 2 and 24 hours, free sanguinarine killed > 90% of B16 melanoma cells, assessed via MTT assay. At 2 hours, sang-np killed a portion of melanoma cells, increasing to percentages comparable to free sanguinarine by 24 hours. Control(empty) nanoparticles exerted minimal toxicity to melanoma cells at both time points. TUNEL assay revealed that treatment with both sanguinarine and sang-np induces apoptosis in B16 melanoma cells, suggesting that both treatments act via the same mechanism of action. These data confirm controlled release of sanguinarine from sang-np, as well as comparable efficacy and mechanism of action to sanguinarine alone. This suggests that nanoparticle delivery of sanguinarine may be a unique approach to capitalize on this potent agent's inherent anti-tumor activity and overcome many of the limitations with its current formulation.

Curcumin improves the therapeutic efficacy of Listeria(at)-Mage-b vaccine in correlation with improved T-cell responses in blood of a triple-negative breast cancer model 4T1.

Success of cancer vaccination is strongly hampered by immune suppression in the tumor microenvironment (TME). Interleukin (IL)-6 is particularly and highly produced by triple-negative breast cancer (TNBC) cells, and has been considered as an important contributor to immune suppression in the TME. Therefore, we hypothesized that IL-6 reduction may improve efficacy of vaccination against TNBC cancer through improved T-cell responses. To prove this hypothesis, we investigated the effect of curcumin, an inhibitor of IL-6 production, on vaccination of a highly attenuated Listeria monocytogenes (Listeria(at)), encoding tumor-associated antigens (TAA) Mage-b in a TNBC model 4T1. Two therapeutic vaccination strategies with Listeria(at)-Mage-b and curcumin were tested. The first immunization strategy involved all Listeria(at)-Mage-b vaccinations and curcumin after tumor development. As curcumin has been consumed all over the world, the second immunization strategy involved curcumin before and all therapeutic vaccinations with Listeria(at)-Mage-b after tumor development. Here, we demonstrate that curcumin significantly improves therapeutic efficacy of Listeria(at)-Mage-b with both immunization strategies particularly against metastases in a TNBC model (4T1). The combination therapy was slightly but significantly more effective against the metastases when curcumin was administered before compared to after tumor development. With curcumin before tumor development in the combination therapy, the production of IL-6 was significantly decreased and IL-12 increased by myeloid-derived suppressor cells (MDSC), in correlation with improved CD4 and CD8 T-cell responses in blood. Our study suggests that curcumin improves the efficacy of Listeria(at)-Mage-b vaccine against metastases in TNBC model 4T1 through reversal of tumor-induced immune suppression.

Cancer vaccination at older age.

Cancer vaccination is less effective at old than at young age, due to T cell unresponsiveness. This is caused by various age-related changes of the immune system, such as lack of naïve T cells, defects in activation pathways of T cells and antigen-presenting cells, and age-related changes in the tumor microenvironment. Natural killer, natural killer T cells, and γδT cells of the innate immune system also change with age but these responses may be more susceptible for improvement than adaptive immune responses at older age. This chapter compares various studies involving adaptive and innate immune responses in elderly and cancer patients, as well as cancer vaccination at young and old age. Finally, potential new directions in cancer vaccination at older age are discussed.