A multi-antigen vaccine in combination with an immunotoxin targeting tumor-associated fibroblast for treating murine melanoma.

A therapeutically effective cancer vaccine must generate potent antitumor immune responses and be able to overcome tolerance mechanisms mediated by the progressing tumor itself. Previous studies showed that glycoprotein 100 (gp100), tyrosinase-related protein 1 (TRP1), and tyrosinase-related protein 2 (TRP2) are promising immunogens for melanoma immunotherapy. In this study, we administered these three melanoma-associated antigens via lentiviral vectors (termed LV-3Ag) and found that this multi-antigen vaccine strategy markedly increased functional T-cell infiltration into tumors and generated protective and therapeutic antitumor immunity. We also engineered a novel immunotoxin, αFAP-PE38, capable of targeting fibroblast activation protein (FAP)-expressing fibroblasts within the tumor stroma. When combined with αFAP-PE38, LV-3Ag exhibited greatly enhanced antitumor effects on tumor growth in an established B16 melanoma model. The mechanism of action underlying this combination treatment likely modulates the immune suppressive tumor microenvironment and, consequently, activates cytotoxic CD8(+) T cells capable of specifically recognizing and destroying tumor cells. Taken together, these results provide a strong rationale for combining an immunotoxin with cancer vaccines for the treatment of patients with advanced cancer.

A potent immunotoxin targeting fibroblast activation protein for treatment of breast cancer in mice.

Fibroblast activation protein (FAP) is highly expressed in the tumor-associated fibroblasts (TAFs) of most human epithelial cancers. FAP plays a critical role in tumorigenesis and cancer progression, which makes it a promising target for novel anticancer therapy. However, mere abrogation of FAP enzymatic activity by small molecules is not very effective in inhibiting tumor growth. In this study, we have evaluated a novel immune-based approach to specifically deplete FAP-expressing TAFs in a mouse 4T1 metastatic breast cancer model. Depletion of FAP-positive stromal cells by FAP-targeting immunotoxin αFAP-PE38 altered levels of various growth factors, cytokines, chemokines and matrix metalloproteinases, decreased the recruitment of tumor-infiltrating immune cells in the tumor microenvironment and suppressed tumor growth. In addition, combined treatment with αFAP-PE38 and paclitaxel potently inhibited tumor growth in vivo. Our findings highlight the potential use of immunotoxin αFAP-PE38 to deplete FAP-expressing TAFs and thus provide a rationale for the use of this immunotoxin in cancer therapy.

Pseudotyping lentiviral vectors with lymphocytic choriomeningitis virus glycoproteins for transduction of dendritic cells and in vivo immunization.

Lentiviral vectors (LVs) are promising delivery systems for gene therapy, and they can be further engineered to increase their potential for effectively delivering transgenes to desired cell populations. Here, we have engineered LVs pseudotyped with envelope glycoproteins derived from lymphocytic choriomeningitis virus (LCMV) for antigen delivery to elicit vaccine-directed immune responses. Two variants, LCMV-WE and LCMV-Arm53b, were evaluated for their ability to mediate LV-based cellular transduction in vitro. LCMV-WE with a leucine residue at position 260 (260L) is known for its high-affinity binding with a cellular receptor, α-dystroglycan (α-DG), whereas LCMV-Arm53b has low-affinity binding resulting from a phenylalanine residue at the same position. In contrast to LCMV-Arm53b, we found that LVs pseudotyped with LCMV-WE could transduce 293T cells and murine dendritic cells much more efficiently based, at least in part, on their favorable interaction with α-DG. In mice, LCMV-WE-bearing LVs encoding a model antigen, invariant chain ovalbumin, could elicit substantial antigen-specific CD8(+) T cell immune response. The response could be further enhanced by a homologous boosting immunization with the same vector. These findings offer evidence to support the potential utilization of LCMV-WE-bearing LVs for vectored vaccines against cancer and infectious diseases.

A tetracycline-regulated cell line produces high-titer lentiviral vectors that specifically target dendritic cells.

Lentiviral vectors (LVs) are a powerful means of delivering genetic material to many types of cells. Because of safety concerns associated with these HIV-1 derived vectors, producing large quantities of LVs is challenging. In this paper, we report a method for producing high titers of self-inactivating LVs. We retrovirally transduce the tet-off stable producer cell line GPR to generate a cell line, GPRS, which can express all the viral components, including a dendritic cell-specific glycoprotein, SVGmu. Then, we use concatemeric DNA transfection to transfect the LV transfer plasmid encoding a reporter gene GFP in combination with a selectable marker. Several of the resulting clones can produce LV at a titer 10-fold greater than what we achieve with transient transfection. Plus, these viruses efficiently transduce dendritic cells in vitro and generate a strong T cell immune response to our reporter antigen. This method may be a good option for producing strong LV-based vaccines for clinical studies of cancer or infectious diseases.

Social media microblogs as an HPV vaccination forum.

The 2006 US FDA approval of the human papillomavirus (HPV) vaccine brought new hope for cancer prevention. Gardasil and Cervarix are widely available vaccines that can deter HPV infection, which causes 70% of cervical cancer. Acceptance of vaccination varies due to a lack of HPV awareness and HPV vaccine knowledge. Recent observations of the Chinese microblog "SinaWeibo" suggest a new approach to engage health professionals and consumer website bloggers. Websites that present the latest fashion, fitness or beauty news and ways to obtain "deals" have created informative blogs or online communities that appeal to female users. Some users raise health questions of their peers. Health professionals, as website bloggers, can introduce vaccine news or respond to conversations between bloggers and their followers. By transforming medical vocabulary into ordinary chat, microblogs may promote efficiency in vaccine education and communication. A web-based, interactive social media-microblog could offer an ideal platform to speed up information dissemination and increase targeted communication.

Brush-shaped polycation with poly(ethylenimine)-b-poly(ethylene glycol) side chains as highly efficient gene delivery vector.

A brush-shaped polymer PHEMA-g-(PEI-b-PEG) with poly(2-hydroxyethyl methacrylate) (PHEMA) backbone and linear poly(ethylenimine)-b-poly(ethylene glycol) (PEI-b-PEG) side chains was synthesized and evaluated as a vector for potential cancer gene therapy. The characterizations by (1)H NMR and laser light scattering demonstrated the brush structure of the polymer. PHEMA-g-(PEI-b-PEG) was much less cytotoxic when compared with branched poly(ethylenimine) with M(w) of 25 kDa. The capacity of plasmid DNA condensation by PHEMA-g-(PEI-b-PEG) was demonstrated by gel retardation assay, and they formed nanosized complexes with surface zeta potential around 20 mV at N/P ratios higher than 5:1. The complexes of PHEMA-g-(PEI-b-PEG) with plasmid DNA were more efficiently internalized by BT474 cells in comparison with the complexes of PEI25K, leading to higher gene transfection in cells. Further investigation using complexes of PHEMA-g-(PEI-b-PEG) with plasmid DNA encoding wild-type p53 gene showed its potential as a carrier for cancer gene therapy. The complexes of PHEMA-g-(PEI-b-PEG) successfully induced elevated wild-type p53 expression in BT474 cells and led to enhanced apoptosis of BT474 cells. Transfection of wild-type p53 using the complexes also significantly increased the sensitivity of BT474 cells to doxorubicin chemotherapy, suggesting the potential of this carrier in cancer gene therapy.