CALGARY, Canada I May 12, 2021 I Providence Therapeutics Holdings Inc. (“Providence“) announced today very favorable interim clinical data of PTX-COVID19-B, its vaccine candidate against SARS-CoV-2 (“COVID-19“), from its Phase 1 study entitled “PRO-CL-001, A Phase 1, First-in-Human, Observer-Blinded, Randomized, Placebo Controlled, Ascending Dose Study to Evaluate the Safety, Tolerability, and Immunogenicity of PTX-COVID19-B Vaccine in Healthy Seronegative Adults Aged 18-64” (the “Phase 1 Study“), which found that PTX-COVID19-B met Providence’s target results for safety, tolerability, and immunogenicity in the participants of the Phase 1 Study.

Highlights from Providence Therapeutics’ “Phase 1 Study”:

  • PTX-COVID19-B was generally safe and well tolerated
  • PTX-COVID19-B exhibited strong virus neutralization capability across the 16µg, 40µg and 100µg dose cohorts
  • PTX-COVID19-B 40µg dose was selected for Phase 2 study
  • PTX-COVID19-B will be evaluated in additional Phase 1 population cohorts

The Phase 1 Study was designed with dose-escalations and was performed in seronegative adult subjects without evidence of recent exposure to COVID-19. The subjects were randomized to receive either the PTX-COVID19-B vaccine or a placebo in a 3:1 ratio. A total of 60 subjects participated in the Phase 1 Study.

The overall results of the Phase 1 Study are that PTX-COVID19-B was safe and well tolerated at the three dose levels of 16µg, 40µg and 100µg. Adverse events identified in the Phase 1 Study were generally mild to moderate in severity, self-resolving and transient. There were no serious adverse events reported in the Phase 1 Study. The most common adverse event reported in the Phase 1 Study was redness and pain at the injection site. Systemic reactions reported in the Phase 1 Study were generally mild to moderate and well tolerated with headache being the most common reaction reported. The reported adverse events of the Phase 1 Study were in line with the expectations of management of Providence as they compare very favorably to the adverse events data published on other mRNA vaccines for COVID-19 that have been approved for use by various health authorities around the world.

Based on the results of the Phase 1 Study, Providence intends to use a 40µg dose for the Phase 2 study of PTX-COVID19-B that is anticipated to be initiated in June 2021. Additional Phase 1 studies in adolescent and elderly populations are also planned to be undertaken by Providence. 

PTX-COVID19-B vaccination induced high anti-S IgG antibodies: 
Participants in the Phase 1 Study were vaccinated on day zero and day twenty-eight. Plasma samples were collected on day 1, day 8, day 28 (prior to the participant receiving the second dose), and day 42 to determine levels of IgG anti-S protein using electrochemiluminescence (“ECL“) assays from Meso Scale Discovery (“MSD“). Study participants in all three vaccine dose cohorts of the Phase 1 Study developed a strong IgG antibody response against Spike protein that was detected by day 28 and enhanced by day 42. No antibodies against S protein were detected in participants in the Phase 1 Study injected with placebo.  The highest levels of antibodies were found in the 40 and 100 µg doses. By day 42, PTX-COVID19-B vaccinated participants had more than one log higher antibody levels than convalescent subjects-plasma (indicated in the dotted line) which was evaluated in the same assay.

Based on the interim data of the Phase 1 Study, the level of antibodies produced in participants by PTX-COVID19-B compare favorably to the levels of antibodies produced by other mRNA vaccines that have been approved for use against COVID-19 based on the recently published report from Stanford University, where IgG responses in individuals vaccinated with the COVID-19 mRNA vaccine compared to COVID-19 infected patients were evaluated1.

1 Röltgen et al. (Apr 7, 2021). mRNA Vaccination Compared to Infection Elicits an IgG-Predominant Response with Greater SARS-CoV-2 Specificity and Similar Decrease in Variant Spike Recognition. Pre-print downloaded May 11, 2021 from https://doi.org/10.1101/2021.04.05.21254952

PTX-COVID19-B vaccination induced high neutralizing antibody levels:

Neutralizing activity from the Phase 1 Study participants’ plasma was evaluated by S-ACE2 MSD assay. The results indicate that the antibodies block the interaction between S protein with the ACE2 receptor and the decrease in ECL signal is used to calculate percentage inhibition of the plasma at the same dilution.  All participants in the Phase 1 Study from the 16, 40 and 100 µg dose levels showed blocking activity by day 28 and all of them reached 100% blocking activity by day 42 with samples diluted 1:100 or greater. Moreover, the quantification of the antibody levels in ng/mL with a reference standard showed that all participants in the Phase 1 Study produced neutralizing antibodies by day 28 with the first immunization and increase ten-fold by day 42, two weeks after the administration of the second dose. These results indicate that PTX-COVID19-B induced a strong neutralizing antibody response which compares very favorably to the published results of other mRNA vaccines. Further studies are being conducted by Providence to determine neutralization activity using a pseudo-virus assay.

Providence intends to advance a Phase 2 clinical trial in early June 2021, with multiple trial sites in Canada. The Phase 2 clinical trial is anticipated to be structured as a comparator trial using Pfizer/BioNTech vaccine as the positive control.

About Providence Therapeutics
Providence is a leading Canadian clinical stage biotechnology company pioneering mRNA therapeutics and vaccines with operations in Calgary, Alberta and Toronto, Ontario. In response to a worldwide need for a COVID-19 vaccine, Providence expanded its focus beyond oncology therapies and devoted its energy and resources to develop a world-class mRNA vaccine for COVID-19. Providence is focused on serving the needs of Canada, and other countries that may be underserved by large pharmaceutical programs. For more information, please visit providencetherapeutics.com. 

SOURCE: Providence Therapeutics