Providence Therapeutics Announces Very Favorable Interim Phase 1 Trial Data for PTX-COVID19-B, its mRNA Vaccine Against COVID-19

CALGARY, AB, May 12, 2021 - Providence Therapeutics Holdings Inc. ("Providence") announced today very favourable 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 favourably 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.

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Based on the interim data of the Phase 1 Study, the level of antibodies produced in participants by PTX-COVID19-B compares favourably 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 evaluated[1].

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 favourably to the published results of other mRNA vaccines. Further studies are being conducted by Providence to determine neutralization activity using a pseudo-virus assay.

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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.

 

Forward-Looking Statements

This press release contains forward-looking statements within the meaning of applicable securities laws including regarding Providence's development of a potential vaccine against COVID-19, and the parameters and timing of the Phase 1 Study and planned Phase 2 study of PTX-COVID19-B. In some cases, forward-looking statements can be identified by terminology such as "will," "may," "should," "could", "expects," "intends," "plans," "aims," "anticipates," "believes," "estimates," "predicts," "potential," "continue," or the negative of these terms or other comparable terminology, although not all forward-looking statements contain these words. The forward-looking statements in this press release are neither promises nor guarantees, and you should not place undue reliance on these forward-looking statements because they involve known and unknown risks, uncertainties, and other factors, many of which are beyond Providence's control and which could cause actual results to differ materially from those expressed or implied by these forward-looking statements. These risks, uncertainties, and other factors include, among others: the fact that the safety and efficacy of PTX-COVID19-B has not yet been established; potential adverse impacts due to the global COVID-19 pandemic such as delays in regulatory review, manufacturing and supply chain interruptions, adverse effects on healthcare systems and disruption of the global economy; the fact that there are a limited number of commercial products utilizing mRNA technology approved for use; and the fact that the mRNA technology in use by Providence is still being developed and implemented. Except as required by law, Providence disclaims any intention or responsibility for updating or revising any forward-looking statements contained in this press release in the event of new information, future developments or otherwise. These forward-looking statements are based on Providence's current expectations and speak only as of the date hereof.

For further information: Media Contacts: Providence Therapeutics: Andrea Chrysanthou, Global Public Affairs, , 416-797-8194 

[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