Preclinical Safety and Biodistribution in Mice Following Single-Dose Intramuscular Inoculation of Tumor DNA Vaccine by Electroporation

The safety, biodistribution, and pharmacokinetics of any new therapeutic tumor DNA vaccine must be evaluated in preclinical studies. We previously developed the DNA vaccine (CpDV-IL2-sPD1/MUC1 and survivin), which showed excellent antitumor effects in a variety of tumor models. In this study, we demonstrate the safety and biodistribution after immunization with naked DNA vaccine (10 mg/kg) by electroporation in a mice model. All mice reached the end of the study with good body conditions. By established and validated QPCR method, we found high-copy plasmid DNA at the injection site (muscle) on day 1 in all eight animals, followed by a downward trend. By day 49, a small amount of plasmid DNA was still detectable, but only in one mouse. On reproductive safety, no plasmids existed in the ovary at any time point. Also, only two of the 16 testis samples could detect a very small amount of DNA on days 7 and 14. The most important thing was that plasmids were cleared from almost all organs (heart, liver, spleen, lung, kidney, stomach, blood, thymus, intestine) on day 49. In summary, the results of our experiments demonstrate that the DNA vaccine delivered by electroporation was shown to be safe and merits further development for cancer treatment.