DNA vaccination for cervical cancer: Strategic optimisation of RALA mediated gene delivery from a biodegradable microneedle system

Abstract

Dissolvable microneedles can be employed to deliver DNA to antigen presenting cells within the skin. However, this technology faces two main challenges: the poor transfection efficacy of pDNA following release from the microneedle matrix, and the limited loading capacity of the micron-scale devices. Two-tier delivery systems combining microneedle platforms and DNA delivery vectors have increased efficacy but the challenge of increasing the loading capacity remains. This study utilised lyophilisation to increase the loading of RALA/pDNA nanoparticles within dissolvable PVA microneedles. As a result, delivery was significantly enhanced in vivo into an appropriate range for DNA vaccination (∼50 μg per array). Furthermore, modifying the manufacturing process was not detrimental to the microneedle mechanical properties or cargo functionality. It was demonstrated that arrays retained mechanical and functional stability over short term storage, and were able to elicit gene expression in vitro and in vivo. Finally, treatment with this novel formulation significantly retarded the growth of established tumours, and proved superior to standard intramuscular injection in a preclinical model of cervical cancer.

Peptide-Based Nanoassemblies in Gene Therapy and Diagnosis: Paving the Way for Clinical Application

“…Arginine-rich peptides are similarly conducive to tight gene condensation, and due to their ability to promote cell penetration, they are effective delivery systems [109,110]. RALA, an amphipathic, cell penetrating peptide with seven arginines in its backbone, formed peptiplexes with siRNA as well as pDNA, which were used as delivery platform in vitro and in vivo ( Figure 7) [111][112][113][114]. By the same token, hydrophilic histidine residues due to their positive charge at physiological pH, bind and condense nucleic acids in aqueous solution [115].…”

“…Schematic illustration of RALA/pDNA peptiplexes formation. Reproduced from[114], with permission. Copyright: 2018 Elsevier.…”

Transcutaneous delivery of DNA/mRNA for cancer therapeutic vaccination

“…Compared to electroporation and gene guns, microneedles can impose a much more extensive skin area, so that the delivered antigens are exposed to more APCs. McCarthy et al . developed a smart PVP dissolving microneedle patch loaded with vaccine nanoparticles, of which the E6/E7 DNA was condensed by the bioengineered cationic CPP via electrostatic interaction.…”

“…123 Compared to electroporation and gene guns, microneedles can impose a much more extensive skin area, so that the delivered antigens are exposed to more APCs. McCarthy et al 63 However, no measurable cell-mediated immune response was observed when electroporated HER2/CEA DNA vaccine followed by adenoviral boost immunization was employed in a phase 1 trial. 134 However, the vaccination protocol was well tolerated without any serious vaccine-related adverse effects.…”

Vaccines Developed for Cancer Immunotherapy

“…Unfortunately, previous clinical trials on DNA cancer vaccines, majority of which were administered as naked DNA via the intramuscular route, showed generally poor response rates, despite employment of viral vectors and electroporation able to improve the transfection of DNA vaccines, both of which cause safety and compliance concerns [61,62]. Alternatively, NPs engineered as a VADS for intracellular delivery of DNA and mRNA provide a promising strategy for developing nucleotide-based cancer vaccines and possess several advantages [6]: (1) synthetic material-constituted NPs are safer than viral vectors, (2) NPs can stabilize and protect gene therapeutics from nuclease-mediated degradation [63], 3DNA-and RNA-loaded NPs can be administered by injection-free tools, such as microneedles for non-parenteral delivery [64], and (4) nanocarriers can be easily modified with targeting moieties, for example, mannose, to achieve DC-targeted delivery and transfection [14,65].…”