SARS-CoV-2 DNA Vaccine INO-4800 Induces Durable Immune Responses Capable of Being Boosted in a Phase 1 Open-Label Trial.

BACKGROUND: Additional severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) vaccines that are safe and effective as primary vaccines and boosters remain urgently needed to combat the coronavirus disease 2019 (COVID-19) pandemic. We describe safety and durability of immune responses following 2 primary doses and a homologous booster dose of an investigational DNA vaccine (INO-4800) targeting 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. CONCLUSIONS: INO-4800 was well tolerated in a 2-dose primary series and homologous booster in all adults, including elderly participants. These results support further development of INO-4800 for use as primary vaccine and booster. CLINICAL TRIALS REGISTRATION: NCT04336410.

INO-4800 DNA vaccine induces neutralizing antibodies and T cell activity against global SARS-CoV-2 variants.

Global surveillance has identified emerging SARS-CoV-2 variants of concern (VOC) associated with broadened host specificity, pathogenicity, and immune evasion to vaccine-induced immunity. Here we compared humoral and cellular responses against SARS-CoV-2 VOC in subjects immunized with the DNA vaccine, INO-4800. INO-4800 vaccination induced neutralizing antibodies against all variants tested, with reduced levels detected against B.1.351. IFNγ T cell responses were fully maintained against all variants tested.

Safety and immunogenicity of INO-4800 DNA vaccine against SARS-CoV-2: A preliminary report of an open-label, Phase 1 clinical trial.

BACKGROUND: A vaccine against SARS-CoV-2 is of high urgency. Here the safety and immunogenicity induced by a DNA vaccine (INO-4800) targeting the full length spike antigen of SARS-CoV-2 are described. METHODS: INO-4800 was evaluated in two groups of 20 participants, receiving either 1.0 mg or 2.0 mg of vaccine intradermally followed by CELLECTRA® EP at 0 and 4 weeks. Thirty-nine subjects completed both doses; one subject in the 2.0 mg group discontinued trial participation prior to receiving the second dose. ClinicalTrials.gov identifier: NCT04336410. FINDINGS: The median age was 34.5, 55% (22/40) were men and 82.5% (33/40) white. Through week 8, only 6 related Grade 1 adverse events in 5 subjects were observed. None of these increased in frequency with the second administration. No serious adverse events were reported. All 38 subjects evaluable for immunogenicity had cellular and/or humoral immune responses following the second dose of INO-4800. By week 6, 95% (36/38) of the participants seroconverted based on their responses by generating binding (ELISA) and/or neutralizing antibodies (PRNT IC50), with responder geometric mean binding antibody titers of 655.5 [95% CI (255.6, 1681.0)] and 994.2 [95% CI (395.3, 2500.3)] in the 1.0 mg and 2.0 mg groups, respectively. For neutralizing antibody, 78% (14/18) and 84% (16/19) generated a response with corresponding geometric mean titers of 102.3 [95% CI (37.4, 280.3)] and 63.5 [95% CI (39.6, 101.8)], in the respective groups. By week 8, 74% (14/19) and 100% (19/19) of subjects generated T cell responses by IFN-É£ ELISpot assay with the median SFU per 106 PBMC of 46 [95% CI (21.1, 142.2)] and 71 [95% CI (32.2, 194.4)] in the 1.0 mg and 2.0 mg groups, respectively. Flow cytometry demonstrated a T cell response, dominated by CD8+ T cells co-producing IFN-É£ and TNF-α, without increase in IL-4. INTERPRETATION: INO-4800 demonstrated excellent safety and tolerability and was immunogenic in 100% (38/38) of the vaccinated subjects by eliciting either or both humoral or cellular immune responses. FUNDING: Coalition for Epidemic Preparedness Innovations (CEPI).

Immunogenicity of a DNA vaccine candidate for COVID-19.

The coronavirus family member, SARS-CoV-2 has been identified as the causal agent for the pandemic viral pneumonia disease, COVID-19. At this time, no vaccine is available to control further dissemination of the disease. We have previously engineered a synthetic DNA vaccine targeting the MERS coronavirus Spike (S) protein, the major surface antigen of coronaviruses, which is currently in clinical study. Here we build on this prior experience to generate a synthetic DNA-based vaccine candidate targeting SARS-CoV-2 S protein. The engineered construct, INO-4800, results in robust expression of the S protein in vitro. Following immunization of mice and guinea pigs with INO-4800 we measure antigen-specific T cell responses, functional antibodies which neutralize the SARS-CoV-2 infection and block Spike protein binding to the ACE2 receptor, and biodistribution of SARS-CoV-2 targeting antibodies to the lungs. This preliminary dataset identifies INO-4800 as a potential COVID-19 vaccine candidate, supporting further translational study.

Gene expression-signature of belinostat in cell lines is specific for histone deacetylase inhibitor treatment, with a corresponding signature in xenografts.

Belinostat is a hydroxamate-type histone deactylase inhibitor (HDACi), which has recently entered phase I and II clinical trials. Microarray-based analysis of belinostat-treated cell lines showed an impact on genes associated with the G2/M phase of the cell cycle and downregulation of the aurora kinase pathway. Expression of 25 dysregulated genes was measured in eight differentially sensitive cell lines using a novel high-throughput assay that combines multiplex reverse transcriptase-PCR and fluorescence capillary electrophoresis. Sensitivity to belinostat and the magnitude of changes in overall gene modulation were significantly correlated. A belinostat-gene profile was specific for HDACi in three cell lines when compared with equipotent concentrations of four mechanistically different chemotherapeutic agents: 5-fluorouracil, cisplatin, paclitaxel, and thiotepa. Belinostat- and trichostatin A (HDACi)-induced gene responses were highly correlated with each other, but not with the limited changes in response to the other non-HDACi agents. Moreover, belinostat treatment of mice bearing human xenografts showed that the preponderance of selected genes were also modulated in vivo, more extensively in a drug-sensitive tumor than a more resistant model. We have demonstrated a gene signature that is selectively regulated by HDACi when compared with other clinical agents allowing us to distinguish HDACi responses from those related to other mechanisms.

Gene expression analysis of troglitazone reveals its impact on multiple pathways in cell culture: a case for in vitro platforms combined with gene expression analysis for early (idiosyncratic) toxicity screening.

Peroxisome proliferator-activated receptor gamma (PPARgamma) agonists of the thiazolidinedione family are used for the treatment of type 2 diabetes mellitus due to their ability to reduce glucose and lipid levels in patients with this disease. Three thiazolidinediones that were approved for treatment are Rezulin (troglitazone), Avandia (rosiglitazone), and Actos (pioglitazone). Troglitazone was withdrawn from the market due to idiosyncratic drug toxicity. Rosiglitazone and pioglitazone are still on the market for the treatment of type 2 diabetes. The authors present data from a gene expression screen that compares the impact these three compounds have in rats, in rat hepatocytes, and in the clone 9 rat liver cell line. The authors monitored the changes in expression in multiple genes, including those related to xenobiotic metabolism, proliferation, DNA damage, oxidative stress, apoptosis, and inflammation. Compared to the other two compounds, troglitazone had a significant impact on many of the pathways monitored in vitro although no major perturbation was detected in vivo. The changes detected predict not only general toxicity but potential mechanisms of toxicity. Based on gene expression analysis, the authors propose there is not just one but multiple ways troglitazone could be toxic, depending on a patient's environment and genetic makeup, including immune response-related toxicity.