In connection with the Q2 2026 report, we have updated our investment case and adjusted our valuation model for the reported Q2 cash position and the revised Phase II timing. 

Q2 2026 delivered the strongest clinical data package ExpreS2ion has produced to date, while the near-term investment question has shifted from the clinic to the balance sheet.

Clinical progress. As of the 4 August data cut, anti-HER2 antibody responses had been observed in 12 of 13 evaluable patients across all three dose levels, up from 9 of 9 across two cohorts in May. All five patients who have completed the five-dose schedule responded, with a median 16-fold peak increase in antibody titre, the first magnitude datapoint the company has published. Titres rose across dosing visits and remained elevated at follow-up. The third DSMB review found no dose-limiting toxicities and no SUSARs, and recommended enrolling three additional patients at 450 µg, an expansion option already provided for in the study design and used previously at 150 µg.

Mode of action. In our view the more substantive development is the functional work. Exploratory assays in non-human primate serum show the induced antibodies engage complement, phagocytosis and cytotoxicity, confirming the intended mode of action. This is mechanistic confirmation rather than evidence of anti-tumour activity, and clinical benefit is not an endpoint in Phase I. The full translational package, including 3D tumour growth inhibition assays, now runs on Phase I patient serum with a read-out in Q4 2026, which gives investors a second dated data point inside the year.

Phase II timing. Phase II initiation moved on 12 August to H2 2027 from mid-2027, to allow the plan to be reviewed with regulators in both Europe and the United States before trial start. Management states the move is unrelated to Phase I safety or efficacy and leaves the funding requirement unchanged. The end-2026 Phase I read-out is unaffected. 

Funding. ExpreS2ion raised SEK 32.4m in the May rights issue and closed Q2 with SEK 34.4m in cash. The 20,218,750 TO 13 warrants were priced on 2 September at the SEK 1.60 floor and are exercisable 7 to 21 September. With the share below the floor, take-up is uncertain. Management points to partnering as the route into Phase II, and further financing is likely if no deal is secured. This is the central near-term uncertainty in the case.

Key catalysts. Two dated events sit inside Q4 2026: the translational package reading out on Phase I serum, and the Phase I primary read-out at end-2026, which will define the dose levels carried into Phase II and remains the principal re-rating trigger. A more detailed preliminary Phase II design is expected around the time of the read-out. Any concrete progress on partnering would, in our view, remain the single biggest non-clinical catalyst.

Key investment reasons: A differentiated HER2-targeting active immunotherapy in a large market of around 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; further derisking through consistent immunogenicity across all three dose levels, now supported by early functional antibody data; and HER2 relevance beyond classic HER2+, including HER2-low breast cancer and HER2-positive GEJ cancer.

Key investment risks: High-risk early-stage development, with ES2B-C001 still in Phase I and dominating the value in the case; antibody responses that have been consistent but where clinical benefit is not a Phase I endpoint and remains unproven against established therapies; dilution risk, with the TO 13 subscription price set above the market and partnering the stated route into Phase II; and concentration on a single catalyst, where a delay or ambiguity in the end-2026 read-out would remove the primary re-rating trigger.

Valuation: The base-case model-implied probability of success now stands at ~1.0%, against the historical benchmark of ~7% for Phase I candidates and ~5% in oncology, with 1.9% in the bear case and 0.6% in the bull case. The market capitalisation sits below the reported cash position, so enterprise value is around zero and the market is ascribing no value to the pipeline and platform. Continued clinical derisking, or a partnering agreement, could therefore trigger a re-rating from a very low base. 

For further insights into the Q2 2026 report and updates from the pipeline and partner programmes, you can watch our Q2 2026 presentation with management here: https://www.inderes.dk/videos/expres2ion-biotech-presentation-of-h1-2026-interim-report

Disclaimer: HC Andersen Capital receives payment from ExpreS2ion Biotech for a Digital IR/Corporate Visibility subscription agreement. Michael Friis and Victor Skriver, 08:15, 07/09-2026.