Linear DNA amplicons as a novel cancer vaccine strategy

Abstract

Background DNA-based vaccines represent a simple, safe and promising strategy for harnessing the immune system to fight infectious diseases as well as various forms of cancer and thus are considered an important tool in the cancer immunotherapy toolbox. Nonetheless, the manufacture of plasmid DNA vaccines has several drawbacks, including long lead times and the need to remove impurities from bacterial cultures. Here we report the development of polymerase chain reaction (PCR)-produced amplicon expression vectors as DNA vaccines and their in vivo application to elicit antigen-specific immune responses in animal cancer models. Methods Plasmid DNA and amplicon expression was assessed both in vitro, by Hela cells transfection, and in vivo, by evaluating luciferase expression in wild-type mice through optical imaging. Immunogenicity induced by DNA amplicons was assessed by vaccinating wild-type mice against a tumor-associated antigen, whereas the antitumoral effect of DNA amplicons was evaluated in a murine cancer model in combination with immune-checkpoint inhibitors (ICIs). Results Amplicons encoding tumor-associated-antigens, such as telomerase reverse transcriptase or neoantigens expressed by murine tumor cell lines, were able to elicit antigen-specific immune responses and proved to significantly impact tumor growth when administered in combination with ICIs. Conclusions These results strongly support the further exploration of the use of PCR-based amplicons as an innovative immunotherapeutic approach to cancer treatment.

Immunogenicity of COVID-eVax Delivered by Electroporation Is Moderately Impacted by Temperature and Molecular Isoforms

“…Indeed, EP technology is prone to a certain level of variability, as we have observed in murine cancer models [ 31 ]. Moreover, it is worth mentioning the indirect evidence observed with linear DNA produced by PCR, which is as immunogenic and efficacious as supercoiled plasmid DNA [ 18 ]. In this recent paper, we compared side-by-side PCR-produced linear DNA and plasmid DNA in gene expression and a cancer vaccine model and showed that the two forms of DNA vaccine delivered by EP resulted in similar immune responses and antitumor effects.…”

“…Other delivery systems based on viral backbones require the use of mammalian cells with higher costs and the potential interference of the expressed transgene with defective viral growth [ 15 ]. Moreover, one recent evolution of DNA-EP technology is the use of complete synthetic DNA, which does not require the use of bacterial growth [ 16 , 17 , 18 ]. However, these technologies are still at the preclinical stage likely due to the lack of a large-scale production process as instead available for plasmid DNA production.…”

A linear DNA vaccine candidate encoding the SARS-CoV-2 Receptor Binding Domain elicits protective immunity in domestic cats

“…Moreover, to increase DNA uptake, we adopted EGT technology for intramuscular delivery, a methodology extensively studied previously 23 . Besides this, our vaccine is based on PCR-based linDNA amplicons, an innovative cell-free vaccination platform that has already proven its efficacy in eliciting in vivo immune responses 13 .…”

“…The copyright holder for this preprint (which this version posted July 22, 2022. ; https://doi.org/10.1101/2022.07.20.500860 doi: bioRxiv preprint plasmid, the cDNA was amplified via PCR by using sequence-specific primers and directionally cloned into the linearized pTK1A-TPA vector by enzymatic restriction PacI/NotI. DNA amplicon construct encoding RBD was synthetized as previously described 13 . Briefly, for the phosphothioate-modified amplicons, a sulfur atom substitutes the non-bridging oxygen in the phosphate backbone of the oligonucleotide.…”

“…Moreover, COVID-eVax has demonstrated its safety and immunogenicity in a first-in-human clinical trial (manuscript submitted). Besides this, new cell-free manufacturing DNA platforms, such as doggybone DNA and PCR-based amplicons such as linDNA, have proven to be stable and immunogenic in preclinical models, thus allowing a highly scalable manufacturing workflow in perspective of massive vaccination for future pandemics 12,13 . Therefore, in order to ensure preparedness in response to increasing reports of COVID-19 in companion animals, we evaluated the safety and immunogenicity of a PCR-based linDNA vaccine, encoding was not certified by peer review) is the author/funder.…”