ExpreS2ion has today announced the outcome of the third scheduled DSMB meeting in the Phase I trial of ES2B‑C001, alongside expanded preliminary immunogenicity and safety data. The DSMB found no dose‑limiting toxicities across the 50 µg, 150 µg and 450 µg cohorts and recommended expanding the top‑dose cohort by three additional patients to strengthen the dataset ahead of the primary readout. Management has accepted the recommendation.

As of the 4 August data cut, 16 patients had been enrolled, with five having completed the full five‑dose schedule. Anti‑HER2 antibody responses were observed in 12 of 13 evaluable patients across all three dose levels, against 9 of 9 evaluable patients at the May update, which covered only the 50 µg and 150 µg levels. All five patients who completed dosing responded, with a median 16‑fold peak increase in antibody titres among completers, and no SUSARs or drug‑related SAEs have been reported. The modestly lower response rate versus the earlier 100 percent reading reflects a larger, more heterogeneous evaluable population that now spans the newly initiated top dose, rather than any weakening of signal; among patients who have finished the regimen, the response rate remains 100 percent.

The Phase I primary readout stays guided for end‑2026, unchanged since the programme's current design was set. Phase II initiation, however, is pushed to H2 2027, from the mid‑2027 target reiterated as recently as the Q1 report in May. Management attributes the shift solely to a decision to align the Phase II protocol with both European and U.S. regulators before trial start, and explicitly disclaims any link to safety or efficacy observations in Phase I. It follows the May redesign that added a maintenance dosing component to the ongoing Phase I programme, and the earlier consolidation of the readout structure, in which a discrete, interim Phase Ia readout originally guided for mid‑2026 was dropped in favour of a single, consolidated end‑2026 readout.

The update lands eight days ahead of the H1 2026 interim report, due 20 August, and inside the TO13 warrant exercise window running through August and September, where the subscription price is set at 70 percent of the volume weighted average share price, floored at SEK 1.60. A clean safety read and a still‑responding, expanding dataset removes one source of catalyst risk going into that measurement period, though the larger cohort and the later Phase II start could increase the funding needs

Investors wanting more detail on how today's data feed into the full H1 picture can join management directly, when ExpreS2ion's CEO Bent U. Frandsen and CFO Keith Alexander will present the H1 2026 interim report and take questions live on 20 August at 10:00:

https://www.inderes.dk/videos/expres2ion-biotech-presentation-of-h1-2026-interim-report

Disclaimer: HC Andersen Capital receives payment from ExpreS2ion Biotech Holding AB for a Digital IR/Corporate Visibility subscription agreement. Michael Friis, 11.16, 12 August 2026.