ExpreS2ion Biotech (EXPRS2) Sachs European Life Science Forum summary

Strategic Overview and Rationale

• ES2B-C001 is an anti-HER2 breast cancer vaccine designed for durable immune control and to address gaps in current therapies.

• The vaccine uses a VLP-based platform presenting the full HER2 extracellular domain to induce a broad polyclonal antibody response.

• Aims to complement existing HER2 therapies, enhance durability, and potentially prevent brain metastases.

• Scalable, off-the-shelf recombinant production supports cost efficiency and broad clinical use.

• The approach leverages proven VLP technology used in successful vaccines like HPV's Cervarix and GARDASIL.

Industry Context and Unmet Needs

• Approximately 2.3 million new breast cancer cases occur annually, with 15% HER2-positive and 45-55% HER2-low cases.

• HER2-targeted therapies have improved survival but are not curative in advanced disease; durability of response remains a challenge.

• Brain metastases are frequent in HER2-positive metastatic cases, and incremental benefit decreases in later treatment lines.

Preclinical and Clinical Data Highlights

• Preclinical models show significant tumor growth inhibition, including in models resistant to monoclonal antibodies.

• Phase I-A clinical study demonstrates a durable, specific antibody response with no safety concerns to date.

• Antibody titers remain high and stable up to six months, with plans to extend observation to one year.

• Patient-level clinical data is available for further discussion.