Adelaide, Australia, 14th July 2025
GPN Vaccines Ltd, a clinical-stage biotechnology company developing a Streptococcus pneumoniae vaccine to prevent life-threatening pneumonia, bacteraemia and meningitis, is pleased to announce positive safety and immunogenicity data from its Phase 1 trial of Gamma-PN, a non-adjuvanted whole cell-pneumococcal vaccine being investigated in elderly adults aged 70 years and over. This follows a previous trial in adults aged 50-69.
In this double-blind, randomised study with an active control, 105 participants received either two doses of 500, 750 or 1000 micrograms of Gamma-PN (n=30 per group) or a single dose of licensed pneumococcal vaccine (Prevenar 13®, n=5 per group). Participants included those with (78%) and without (22%) previous pneumococcal vaccination.
The study met its primary safety objective, demonstrating a safety profile suitable for further development. There were no serious adverse events attributed to Gamma-PN and systemic tolerability was considered excellent. Injection site reactions were largely confined to mild to moderate erythema and swelling, typically of short (1-2 day) duration, with the frequency and extent being dose-related. Local and systemic tolerability after the second injection of Gamma-PN was similar to that after the first.
An immunological assessment of serum IgG responses to vaccination with Gamma-PN was performed using an ELISA developed and run by a GLP-accredited third-party laboratory. This demonstrated that Gamma-PN induced rises in serum IgG levels to Gamma-PN after both the first and second vaccine dose. The increase was similar across all dose levels and was no less than the increases seen at the highest dose level in the previous study in participants aged 50-69, none of whom had been previously immunised with a licensed pneumococcal vaccine.
GPN Vaccines is also conducting additional immunological tests on serum including an assessment of opsonophagocytic antibodies against Streptococcus pneumoniae serotypes covered by current licensed pneumococcal vaccines as well as serotypes not covered by such vaccines. These results will be reported once complete.
In addition, an extension trial in which serum samples were taken at 6 and 12 months after vaccination from the first clinical trial showed sustained elevations in IgG at all doses at 6 months and at the two higher doses at 12 months.
Professor Paul Rolan, GPN Vaccines’ Chief Medical Officer commented “The main adult population at risk for serious pneumococcal disease is the elderly because of waning immunity over time. We are delighted to see that the immune response to Gamma-PN was no less in our elderly participants aged 70 and over than in those aged 50 to 69. We also saw no difference in response between those with and without previous pneumococcal vaccination suggesting a predictable immune response across the target population. I would like to extend my appreciation to all of the participants who volunteered to be in this clinical trial. The study demonstrated that Gamma-PN is safe, well tolerated and encompassed the doses to be selected for further clinical development. The sustained immune response is especially encouraging.”
Dr Tim Hirst, Chairman and Chief Executive Officer said “I am delighted we can announce further positive clinical trial results on our broad-spectrum pneumococcal vaccine designed to offer protection against all serotypes of Streptococcus pneumoniae. These results provide important data which will underpin pivotal clinical trials to support international product approval.”.
The extension trial was generously supported by a $900,000 grant from Cureator.
About GPN Vaccines
GPN Vaccines is a public (unlisted) biotechnology company developing a vaccine against Streptococcus pneumoniae, which is responsible for causing life-threatening pneumonia, bacteraemia and meningitis, as well as otitis media (middle ear infections). Each year it causes 1-2 million deaths worldwide, killing more children than AIDS, malaria and tuberculosis combined. There are now more than 100 different serotypes of S. pneumoniae and the best vaccine currently on the market only protects against 20 of them. GPN Vaccines’ product, called Gamma-PN, is being developed to protect children and adults against all S. pneumoniae strains, regardless of serotype.
Media contacts
Dr Tim Hirst
Chief Executive Officer
tim@gpnvaccines.com
+61 420 942 824
