The major obstacle to the preventive or therapeutic success of DNA vaccines is undoubtedly their delivery. If this cannot be made simple, cheap and effective, they may not become a viable option for human use. Numerous clinical trials have confirmed that a standard needle and syringe parenteral (mainly intramuscular or intradermal) delivery is not enough. An important tenet, confirmed by different DNA immunization studies, is that electroporation dramatically enhances the expression of the encoded antigen as well as the potency and immunogenicity of DNA vaccines. Electroporation (EP) creates transient increases in cell membrane permeability, thus enhancing DNA uptake and leading to a more robust immune response. EP involves the application of brief electric pulses to tissue in order to permeabilize cell membranes in a transient and reversible manner. The temporary formation of pores facilitate successful transport of macromolecules, like DNA, that occurs on the order of microseconds vs. minutes in the case of passive diffusion alone. EP is considered a safe and well validated procedure that can easily be handled as an out-patient procedure. In this regard, electrochemotherapy and electro gene transfer with the Cliniporator® (IGEA Srl, Carpi, Italy) has been added to clinical practice.
Aim of the present study is therefore to formally confirm the tolerability of electroporation given by the EPSGT gun and the Cliniporator® device in a clinical setting of healthy volunteers, prior to the phase I/II study of the COVID-19 vaccine in a similar population.
Twenty (20) subjects will be randomized 1:1 to one of the following EP conditions:
- voltage amplitude of 40 V (10 subjects)
- voltage amplitude of 60 V (10 subjects). For the purpose of the study, 0.5 ml of sterile 0.9% saline solution will be injected intramuscularly into the deltoid muscle of the right arm using a common insulin syringe inserted in the EPS gun; the saline injection will immediately be followed by electroporation given by the gun connected to the electrical pulse generator, Cliniporator®.
The electroporation technology has been optimized by IGEA developing a dedicated EPS electrode gun. The EPS gun is an intuitive and handful procedure that combines in the same device the injection of a DNA vaccine (or a sterile 0.9% saline solution as in the case of the present study) and the delivery of the electrical pulses; the procedure is completed in few seconds. The EP needles 7 (diameter 0.45 mm) are hidden under a sliding cap integrated into the EPS gun, to reduce perceived pain potentially associated to anxiety or fear. The EPS gun allows the insertion of both the electrode needles and the syringe needle into the muscle. By pressing the syringe plunger, the content of the syringe will be injected, by pulling the trigger the syringe needle will be retracted, and finally the electrical pulses will be delivered by pressing a pedal connected to the pulse generator.
On the day of injection and EP, subjects will be instructed to measure the length of time pain is experienced by using a stopwatch. Additionally, subjects will complete the Visual Analog Scale (VAS) to rate the level of pain experienced immediately (0 min) and after 5 min, 15 min, 30 min, and 60 min post-EP. In addition subjects will rate discomfort level using an 11-point numerical rating scale (NRS), evaluated 60' (T4) after the procedure. On Day 2 and Day 7 post-EP, subjects will complete again the VAS as described above, and NRS. In addition, on Day 1 (T2, +15'), Day 2 and Day 7 subjects will complete a self-administered questionnaire assessing the acceptance of the procedure. Therefore, to better measure the acceptability of the injection related to the use of a new device from people's own perspectives, all participants will complete the Perception of Injection (PIN) questionnaire, adapted from the Vaccines' Perception of Injection (VAPI) questionnaire.
Safety analyses will include summaries of the following:
- adverse events, including severity and relationship to the procedure (to the intramuscular injection, to the electroporation, or to both procedures)
- serious adverse events, including severity and relationship to the procedure (to the intramuscular injection or to the electroporation, or to both)
- abnormal changes in CPK
- abnormal changes in vital signs and ECG
Sample size and Statistical Analysis:
No sample size calculation was performed on this study on the tolerability of two EP voltage strengths.
The statistical analyses will be mainly descriptive. Qualitative variables will be summarized by counts and percentages, while quantitative characteristics by quartiles or mean and standard deviation, as appropriate.
Data collected longitudinally will be also described appropriately. Specific summary indices will be calculated on the longitudinal VAS profiles (e.g. SPID and peak PID) and the agreement between VAS and NRS collected at each time point will be also assessed.
All adverse events will be graded in accordance with the 2007 FDA toxicity grading scale for healthy adult and adolescent volunteers enrolled in preventive vaccine clinical trials (grade 1 = mild, grade 2 = moderate, grade 3 = severe, grade 4 = life-threatening) and will be reported as percentages and narratives will be also presented.
The data requested by the study will be reported in an electronic remote data capture system (e-CRF). The subject data collected in the e-CRF during the study will be documented anonymously and the subject can only be identified by an identification code.