26th Annual Biotech in Europe Forum

Oct 7, 2026

Slides

Summary

ES2B-C001 phase I showed at least a twofold anti-HER2 antibody-titer increase in 12 of 13 evaluable patients, with no dose-limiting toxicities reported to date. A controlled phase II study is planned for H2 2027, subject to data, regulatory alignment and financing.

My name is Bent Frandsen. I am the CEO of ExpreS2ion. We are developing ES2B-C001, which is an active immunotherapy for HER2-expressing cancers. Our aim is to add a broad immune response to established HER2 treatments. Today, I will explain the rationale, the early clinical evidence, and the next development milestones. First of all, ExpreS2ion, it is a clinical-stage biotech listed on Nasdaq First North in Sweden, but all operations take place in Denmark, in the Copenhagen region. We have a proprietary protein platform that we call ExpreS2. It produces complex recombinant proteins, including the HER2 component in ES2B-C001. It has supported more than 500 proteins and VLP projects since we started operations, including getting to clinical phase III. We have partnered programs in malaria, Nipah, and influenza as well. We have substantial platform foundation. For investors and pharmaceutical partners here today, the focus is on our phase I oncology program and the opportunity to test whether active HER2 immunotherapy adds clinical benefit to established treatments. HER2, as you are probably all aware of, is a very established target. It has been around for decades. There is a substantial treatment landscape. Our strategy is to build on that biology through combination treatment. Established HER2 therapies provide direct anti-tumor activity. ES2B-C001 is designed to add antibodies generated by the patient's own immune system against multiple HER2 epitopes. The rationale is to combine those complementary approaches and test whether they can extend disease control. A broad and durable response is the goal, with immune memory still to be evaluated. Commercially, our opportunity is to add value alongside established HER2 treatments, which makes the combination strategy central to our partnering proposition. For a pharmaceutical partner, the key question is whether adding active immunotherapy to a suitable backbone can improve outcomes with acceptable safety. That is the question we intend to address in phase II. A bit around the design of ES2B-C001. It displays the full extracellular domain of HER2, all four domains on a non-infectious virus-like particle, a VLP. This high-density display is designed to induce a polyclonal antibody response against multiple HER2 epitopes. In other words, we aim to stimulate the patient's immune system to produce a range of HER2-directed antibodies. We produce the HER2 component using our ExpreS2 platform and combine it with a proprietary VLP technology. It is an off-the-shelf product which provides a practical basis for combination development. We are now characterizing the breadth, function, and durability of the human antibody response. The open-label phase I study evaluates safety, tolerability, and immunogenicity in advanced HER2 positive or HER2-low breast cancer patients. We have tested three dose levels, 50 micrograms, 150, and 450 micrograms. In the approved aggregate update, 12 of 13 evaluable patients showed at least a twofold increase in anti-HER2 antibody titers from baseline. Evaluable means at least two immunizations and both baseline and follow-up samples. This is an immune response measure. It is not a tumor response rate. Responses have been observed across the three dose levels, and titers have increased with repeated dosing. Durability remains under evaluation as follow-up matures. No dose-limiting toxicities have been reported to date. These findings support continued development, but this is a small, uncontrolled study in patients also receiving cancer treatment. It cannot establish the added clinical efficacy of ES2B-C001, but we are getting there with our plans for getting into phase II next year. Antibody quantity is one part of the story. We also need to understand what those antibodies do. These exploratory assays use antibodies from vaccinated non-human primates, which were part of our preclinical safety and tox studies ahead of our first clinical study. They show activity through the complement system, through phagocytosis, and cell-mediated killing against HER2-expressing cells. They provide a preclinical support for the intended mechanism of action. We are now running the same three assays with phase I patient serum, and results are expected before the end of the year. Together with the antibody breadth and durability, these results will help us assess the human response and inform dose selection. For a combination partner, pharmaceutical partner, this evidence should help define the most useful questions to test in phase II. Phase II is going to answer a very central question. Does adding ES2B-C001 add clinical benefit? Our current planning direction is a controlled study comparing ES2B-C001 plus a HER2 treatment backbone with the backbone alone. We expect to enroll in the range 80-120 patients. We are evaluating earlier line HER2-positive disease with progression-free survival as the proposed clinical objective and supported by safety and immune measures. This is going to start in the second half of 2027. The phase I package and regulatory input will guide the backbone, the dose, and the booster schedule before we finalize the protocol. Our next investment milestone is the integrated phase I package, which is targeted for around the end of this year. In the first half of 2027, we plan to use those results to finalize the protocol and advance regulatory dialogue and prepare for manufacturing for phase II. Phase II initiation, as I mentioned, is targeted for the second half of 2027, of course, subject to data, regulatory alignment, and financing. We are seeking investors to support phase II and pharmaceutical partners that are interested in adding an active HER2 immunotherapy to their treatment backbone. We also welcome discussions on regional licensing and co-development, and the opportunity really is to help shape a controlled test of added clinical benefit informed by the upcoming phase I package. If that fits your portfolio or investment focus, I will welcome a discussion here. Thank you very much.