ExpreS2ion announces positive topline results for its HER2-cVLP breast cancer vaccine, demonstrating animal proof-of-concept

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Hørsholm, Denmark, December 22, 2021 – ExpreS2ion Biotech Holding AB’s affiliate ExpreS2ion Biotechnologies ApS (“ExpreS2ion") announces that its capsid virus-like particle (cVLP) breast cancer vaccine candidate ES2B-C001 demonstrated strong tumor-growth inhibiting effect in a mice model, thus reaching an important pre-clinical milestone ahead of schedule. Additionally, anti-HER2 antibodies from these studies were found to effectively inhibit tumor growth in human cancer cells. The therapeutic vaccine is being developed towards first in human clinical trials in 2023.

The topline preclinical results reported today by ExpreS2ion are based on data from therapeutic studies in mice challenged intravenously and subcutaneously with HER2-positive breast cancer tumors. Two weeks after the inoculation of tumor cells, the first vaccine administrations were given. ES2B-C001 formulated in an adjuvant was found to totally block tumor development, whereas the control group progressively expanded with lung metastases and subcutaneously growing local tumors. Additionally, ES2B-C001 without adjuvant was found to inhibit, but not prevent, tumor development.

Furthermore, in vitro proof-of-concept studies have been conducted. These studies showed that when blood serum from vaccinated mice were applied to cultures of HER2-positive human breast cancer tumors, the growth was effectively inhibited. The inhibition indicates that the anti-HER2 antibodies mediate the arrest of tumor growth. When vaccine generated anti-HER2 antibodies in blood serum were applied in the same concentration as the conventional HER2-targeting monoclonal antibody, trastuzumab, tumor growth was inhibited to the same extent. Even in the case of using trastuzumab-resistant tumor cells, the vaccine generated anti-HER2 antibodies efficiently inhibited tumor growth.

CEO Bent Frandsen comments:        

“These excellent topline results from the ExpreS2ion-sponsored on-going preclinical trial confirm that the ES2B-C001 breast cancer vaccine has a strong therapeutic potential. It is also encouraging to see that it may fulfill the more specific unmet need for trastuzumab-resistant metastatic breast cancer patients. We remain on track to continue development towards a first in human trial in 2023.”

Results from remaining on-going animal proof of concept studies are expected later in the first half of 2022. The vaccine project continues to be on path, with the start of the clinical program planned for 2022 with GMP manufacturing of ES2B-C001. This will be followed by, pending feedback from regulatory authorities, the start of a clinical Phase I safety and immune response study in 2023.

About ES2B-C001 and breast cancer

Breast cancer is a widespread oncology indication affecting more than 1.3 million people worldwide annually, resulting in more than 450,000 deaths (Tao, 2015: www.ncbi.nlm.nih.gov/pubmed/25543329). The most common treatment today is based on monoclonal antibodies, where the dominating therapy Herceptin (trastuzumab) generates annual global sales of USD 7 billion. The target product profile of the HER2-cVLP breast cancer vaccine candidate is tailored to be highly competitive both in terms of cost and efficacy, thus aiming at a significant market share.

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This press release constitutes inside information that ExpreS2ion Biotech Holding AB (publ) is obliged to make public pursuant to the EU Market Abuse Regulation 596/2014. The information was sent for publication, through the agency of the contact persons set out above, at the time stated by the Company’s news distributor, Cision, at the publication of this press release.

For further information about ExpreS2ion Biotech Holding AB, please contact:

Bent U. Frandsen, CEO
Telephone: +45 4256 6869

Keith Alexander, CFO
Telephone: +45 5131 8147

About ExpreS2ion

ExpreS2ion Biotechnologies ApS is a fully owned Danish subsidiary of ExpreS2ion Biotech Holding AB with company register number 559033-3729. ExpreS2ion has developed a unique technology platform, ExpreS2, for fast and efficient non-clinical development and production of complex proteins for new vaccines and diagnostics. ExpreS2 is regulatorily validated for clinical supply. The platform includes functionally modified glycosylation variants for enhanced immunogenicity and pharmacokinetics. Since 2010, the Company has produced more than 300 proteins and 40 virus-like particles (VLPs) in collaboration with leading research institutions and companies. Since 2017, ExpreS2ion develops novel capsid VLP based vaccines through its 34%-owned joint venture AdaptVac ApS. For additional information, please visit www.expres2ionbio.com and www.adaptvac.com.