ExpreS2ion: Clearance to advance ES2B-C001 – supportive early signals, but still preliminary

ExpreS2ion today reported updated immunogenicity data from the first three patients treated with its HER2-targeted breast cancer vaccine candidate ES2B-C001, alongside confirmation that the independent Data Safety Monitoring Board (DSMB) has reviewed safety data and recommended progression to the next dose cohort in the ongoing Phase I trial.

 The updated data show induction of HER2-specific antibody responses in multiple patients, with antibody levels rising significantly above baseline following vaccination. Early follow-up data further suggest that these vaccine-induced immune responses may be maintained during the monitoring period without an apparent decline. While encouraging, these observations are based on a small patient cohort and exploratory analyses and should therefore be interpreted with caution.

 Importantly, the DSMB’s recommendation to advance from the low-dose (50 µg) to the mid-dose (150 µg) cohort supports the safety profile observed to date and represents a key operational milestone for the program. The company will now enroll and vaccinate the next cohort while continuing immunogenicity and safety assessments.

 Overall, the update provides additional early biological validation of ES2B-C001 and supports continued clinical development. However, the dataset remains limited and early-stage, and we do not expect this read-out alone to materially change probability-adjusted valuation assumptions. More mature data across additional patients and dose levels might be required before the market is likely to reassess the asset’s risk profile.

 From a valuation perspective, our DCF-modelling approach suggests that the market is discounting around a 3-4% chance of ExpreS2ion Biotech’s success, including its ES2B-C001 candidate and technology platform (POS). With the small patient population and the early data, more mature data across additional patients and dose levels might be required before the market is likely to reassess the probability of success (POS) they are willing to price into the share.

 We, however, also note that this study is again showing an induced immune response that is maintained over a longer period, something also observed in other studies. We might therefore be too conservative when assigning value to the technology platform in our modelling.

 You can read more about our assumptions behind the calculated POS in our latest one-pager analysis here: https://www.inderes.dk/research/expres2ion-biotech-one-pager-pipeline-focus-on-her2-breast-cancer-therapy

Disclaimer: HC Andersen Capital receives payment from ExpreS2ion Biotechnologies for a DigitalIR/corporate visibility subscription agreement. / Michael Friis 13:01 19/12-2025