The cellular machinery is needed to generate tumour antigens and other necessary proteins are provided by the host and not required to be incorporated into

the vaccine itself. Finally, the DNA backbone of the injected plasmid contains its own cognate immunostimulatory sequences, which have been shown to activate innate responses [35]. However, disadvantages to DNA vaccines are their relatively low transfection efficiency and poor immunogenicity. Many strategies have been employed to overcome these obstacles mostly see more trying to produce: an efficient delivery of targeted antigen to antigen presenting cells such as DCs; an enhancement of antigen processing and presentation in DCs; and an augmentation of DC and T cell interaction [36]. Recently, it has been reported that the fusion of the E7 gene of HPV 16 with a plant virus coat protein produced strong antitumour activity in a mouse model activating both CD4+ and CD8+ T cells [37]. A clinical PFT�� ic50 trial with the administration of liposome-encapsulated plasmid IL-2 in combination with chemotherapeutics,

was conducted and robust IFN-γ and IL-12 titers were detected in patients with advanced HNSCC [38]. Similarly, phase I clinical trial using a naked DNA vaccine encoding the HPV-16 E7 gene linked to M. tuberculosis HSP70 (pNGVL4a-Sig/E7(detox)/HSP70) is conducting at the Johns Hopkins Hospital (USA) in patients with advanced HPV-16 associated HNSCC. The DNA vaccine was well tolerated and a subset of the vaccinated patients demonstrated detectable systemic levels of E7-specific CD8+ T cell immune responses (M. Gillison and T.C. Wu, personal communication). Bacterial/viral

vectors Bacteria, such as Listeria monocytogenes, Salmonella, Lactococcus lactis, Lactobacillus plantarum, Bacillus Calmette-Guerin, and several viral vectors, including vaccinia virus (VV), adenovirus, adeno-associated virus, alphavirus, and its derivative vectors, such as sindbis virus, semliki forest virus, and venezuelan equine encephalitis virus have been used to deliver genes or proteins of Suplatast tosilate interest to elicit antigen-specific immunotherapy [for review, [39]]. Among the bacterial vectors, L. monocytogenes has emerged as a promising vector, because in animal models it is able to induce both CD8+ and CD4+ immune responses to elicited regression of established tumours, and to overcome central tolerance by expanding low avidity CD8+ T cells specific for E7 [40]. Among viral vectors, VV was historically one of the first viral vector employed in clinical trials of https://www.selleckchem.com/products/tariquidar.html therapeutic vaccines against HPV-associated cancer [41]. To date many VV vaccines have been employed in clinical trials to deliver genes and antigens of interest efficiently.