Abstract
Background
Additional SARS-CoV-2 vaccines that are safe and effective as primary vaccines and boosters remain urgently needed to combat the COVID-19 pandemic. We describe the safety and durability of the immune responses following two primary doses and a homologous booster dose of an investigational DNA vaccine (INO-4800) targeting the full-length spike antigen.
Methods
Three dosage strengths of INO-4800 (0.5 mg, 1.0 mg, and 2.0 mg) were evaluated in 120 age-stratified healthy adults. Intradermal injection of INO-4800 followed by electroporation at 0 and 4 weeks preceded an optional booster 6-10.5 months after the second dose.
Results
INO-4800 appeared well tolerated, with no treatment-related serious adverse events. Most adverse events were mild and did not increase in frequency with age and subsequent dosing. A durable antibody response was observed 6 months following the second dose; a homologous booster dose significantly increased immune responses. Cytokine producing T cells and activated CD8+ T cells with lytic potential were significantly increased in the 2.0 mg dose group.
Conclusion
INO-4800 was well tolerated in a 2-dose primary series and as a homologous booster in all adults, including the elderly. These results support further development of INO-4800 for use as a primary vaccine and as a booster.
Keywords: SARS-CoV-2, Clinical trial, DNA Vaccine, INO-4800, COVID-19, Safety, Immunogenicity, Booster
Contributor Information
Kimberly A Kraynyak, Inovio Pharmaceuticals, Plymouth Meeting, PA, USA.
Elliott Blackwood, Inovio Pharmaceuticals, Plymouth Meeting, PA, USA.
Joseph Agnes, Inovio Pharmaceuticals, Plymouth Meeting, PA, USA.
Pablo Tebas, Hospital of the University of Pennsylvania, Philadelphia, PA, USA.
Mary Giffear, Inovio Pharmaceuticals, Plymouth Meeting, PA, USA.
Dinah Amante, Inovio Pharmaceuticals, Plymouth Meeting, PA, USA.
Emma L Reuschel, Vaccine and Immunotherapy Center, Wistar Institute, Philadelphia, PA, USA.
Mansi Purwar, Vaccine and Immunotherapy Center, Wistar Institute, Philadelphia, PA, USA.
Aaron Christensen-Quick, Inovio Pharmaceuticals, Plymouth Meeting, PA, USA.
Neiman Liu, Inovio Pharmaceuticals, Plymouth Meeting, PA, USA.
Viviane M Andrade, Inovio Pharmaceuticals, Plymouth Meeting, PA, USA.
Malissa C Diehl, Inovio Pharmaceuticals, Plymouth Meeting, PA, USA.
Snehal Wani, Inovio Pharmaceuticals, Plymouth Meeting, PA, USA.
Martyna Lupicka, Inovio Pharmaceuticals, Plymouth Meeting, PA, USA.
Albert Sylvester, Inovio Pharmaceuticals, Plymouth Meeting, PA, USA.
Matthew P Morrow, Inovio Pharmaceuticals, Plymouth Meeting, PA, USA.
Patrick Pezzoli, Inovio Pharmaceuticals, Plymouth Meeting, PA, USA.
Trevor McMullan, Inovio Pharmaceuticals, Plymouth Meeting, PA, USA.
Abhijeet J Kulkarni, Vaccine and Immunotherapy Center, Wistar Institute, Philadelphia, PA, USA.
Faraz I Zaidi, Vaccine and Immunotherapy Center, Wistar Institute, Philadelphia, PA, USA.
Drew Frase, Vaccine and Immunotherapy Center, Wistar Institute, Philadelphia, PA, USA.
Kevin Liaw, Vaccine and Immunotherapy Center, Wistar Institute, Philadelphia, PA, USA.
Trevor R F Smith, Inovio Pharmaceuticals, Plymouth Meeting, PA, USA.
Stephanie J Ramos, Inovio Pharmaceuticals, Plymouth Meeting, PA, USA.
John Ervin, Alliance for Multispecialty Research, Kansas City, MO, USA.
Mark Adams, Alliance for Multispecialty Research, Lexington, KY, USA.
Jessica Lee, Inovio Pharmaceuticals, Plymouth Meeting, PA, USA.
Michael Dallas, Inovio Pharmaceuticals, Plymouth Meeting, PA, USA.
Ami Shah Brown, Inovio Pharmaceuticals, Plymouth Meeting, PA, USA.
Jacqueline E Shea, Inovio Pharmaceuticals, Plymouth Meeting, PA, USA.
J Joseph Kim, Inovio Pharmaceuticals, Plymouth Meeting, PA, USA.
David B Weiner, Vaccine and Immunotherapy Center, Wistar Institute, Philadelphia, PA, USA.
Kate E Broderick, Inovio Pharmaceuticals, Plymouth Meeting, PA, USA.
Laurent M Humeau, Inovio Pharmaceuticals, Plymouth Meeting, PA, USA.
Jean D Boyer, Inovio Pharmaceuticals, Plymouth Meeting, PA, USA.
Jr. Mammen P Mammen, Inovio Pharmaceuticals, Plymouth Meeting, PA, USA.
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