ExpreS2ion (Investment Case): Q1 2026 - continued progress across pipeline and partner programmes

In connection with the Q1 2026 report, we have updated our investment case.

Q1 2026 has moved ExpreS2ion meaningfully forward and further derisked the investment case, with continued positive ES2B-C001 read-outs, a redesigned and strengthened Phase I programme, and a completed rights issue potentially securing the company's path to the end-2026 Phase I read-out.

On the clinical side, all 9 evaluable patients in the 50 µg and 150 µg cohorts have shown anti-HER2 antibody responses, with titres continuing to rise across dosing visits and remaining elevated at later follow-up. The first patient in the 450 µg cohort has been dosed following DSMB approval, with no safety signals of concern. Partner-led programmes also progressed, with new Oxford BIO-002 malaria data validating the ExpreS2 platform and Northway Biotech selected as CDMO for Nipah.

The more substantive element of the recent updates, in our view, is the redesign of the Phase I programme itself. Three changes stand out.

First, management has added three new bioanalyses covering mode of action, potential early efficacy and polyclonality, with management indicating that this will provide a materially richer data package for potential partners as part of the end-2026 Phase I read-out. Management has also indicated that the broader translational programme has been added in response to feedback from potential development partners and investors, in our view a useful signal that partnering dialogue is mowing.

Second, the planned separate dose-expansion stage has been replaced with a maintenance phase of up to 18 months, evaluating booster dosing and the durability of the immune response – directly addressing the key differentiation point versus existing monoclonal antibodies and antibody-drug conjugates, which are not long-term therapies.

Third, the Phase II design has been revised toward a more targeted, focused and capital-efficient proof-of-concept study. Combined, the changes strengthen the partnering data package without shifting the end-2026 Phase I read-out or mid-2027 Phase II initiation timeline.

Management's commentary on partnering has also sharpened. Management indicated on the Q1 webcast that partner interest has increased on the back of the consistent positive 2026 data points, and that the company is exploring multiple partnering scenarios based on the Phase I package.

On the funding side, ExpreS2ion closed Q1 2026 with SEK 21.8m in cash. The subsequent rights issue closed at ~59.9% subscription, providing ~SEK 31.8m in initial gross proceeds, with the TO 13 warrant exercise window in late August/early September 2026 potentially adding up to ~SEK 32.4m. Management indicated on the Q1 webcast that the company has the capital to reach the warrant programme and is cautiously optimistic that the warrants will provide sufficient capital to reach all Phase I objectives.

The key catalyst over the next 12 months is the ES2B-C001 Phase Ib read-out at end-2026, which will define MTD and the recommended Phase II dose. Ahead of that, investors should watch for interim 450 µg cohort data, the outcome of the TO 13 warrant exercise window, further detail on the revised Phase II design, and Oxford-led malaria read-outs from Q3 2026 onwards. Any concrete progress on partnering discussions for ES2B-C001 would, in our view, be the single biggest non-clinical catalyst.

Our investment case includes Key investment reasons and risk as well as valuation perspectives.

Key investment reasons: A differentiated HER2-targeting cancer vaccine in a large market (~USD 16bn) where existing therapies face resistance and safety limitations; a technology platform validated in a Phase III COVID-19 trial and through malaria partnerships; partial derisking of ES2B-C001 through encouraging early immunogenicity and safety data; and HER2 relevance beyond classic HER2+, including HER2-low breast cancer and HER2-positive GEJ cancer.

Key investment risks: High-risk early-stage drug development, with ES2B-C001 still in Phase I; continued dilution risk, as further dilutive financing is likely needed to reach the later-stage clinical milestones required for partnering; and clinical timing risk, where further enrolment delays could pressure the expected cash runway and push key readouts beyond the TO 13 exercise window.

Valuation: We use a scenario-based DCF approach and the focus on the market-implied probability of success (PoS) . The base-case model-implied PoS stands at ~1.2%, compared with the historical benchmark of ~7% for Phase I candidates (bear: 2.0%, bull: 0.5%). The low implied PoS could reflect investor concerns about additional capital needs, uncertainty around realistic peak market penetration, and the subdued risk appetite for Nordic small-cap biotech – meaning continued clinical derisking and a potential partnering deal could trigger a re-rating.

For further insights into the Q1 2026 report and updates from the pipeline and partner programmes, you can watch our Q1 2026 presentation with management here:

https://www.inderes.dk/videos/expres2ion-biotech-presentation-of-q1-2026-interim-report

Disclaimer: HC Andersen Capital receives payment from ExpreS2ion Biotech for a digitalIR/Corporate Visibility subscription agreement. Michael Friis, 08:00, 29/05-2026.