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.

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 proceeding with the remaining three patients of the pre‑planned six‑patient top‑dose cohort, having reviewed the first three. Management has accepted the recommendation; the cohort size itself is unchanged from the original trial design.

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 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 Phase II plan itself, including its cost and funding requirement, remains under development.

The update lands eight days ahead of the H1 2026 interim report, due 20 August, which also marks the start of the VWAP measurement period for the TO13 warrants, running from 20 August to 2 September 2026. The subscription price will be set at 70 percent of the volume weighted average share price over that period, floored at SEK 1.60, ahead of the actual exercise window running from 7 to 21 September 2026. A clean safety read across an unchanged cohort design removes one source of pricing risk going into the measurement period

Investors wanting more detail on how today's data feed into the full H1 picture can join management directly. 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. (Updated 15:43, 13 August 2026)