ExpreS2ion Biotech: Slow start in phase 1

Initial milestone not achieved in Q1

ExpreS2ion Biotechnologies guided early February for starting treatment of the first patient in its phase 1 study during the course of the first quarter. However, so far, no patients have been included, and we speculate that this delay may push the start of the second part of the study into early next year.

The study is expected to include up to twenty-seven HER2 positive breast cancer patients and investigates the safety and immunogenicity of the vaccine candidate ES2B-C001. Before moving into the second part of the study, investigators will perform a safety analysis on nine patients in the initial dose-escalation part.

Amendment to study protocol

The structure of a clinical study is mastered by the study protocol, which sets out criteria for which type of patients can participate. In order to accelerate the enrolment to the ES2B-C001 study management has applied for an expansion of the current protocol, which allows for only trastuzumab-treated patients, to also include patients that are concurrently receiving Enhertu or other antibody-drug conjugates (ADCs). We expect the Austrian Health Care Agency BASG to confirm the amendment in the third quarter.

Enhertu transforming the HER2 landscape

Enhertu is rapidly overtaking the position as standard-of-care for in metastatic HER2 positive breast cancer, which is the target population for ES2B-C001. Enhertu is an Antibody-Drug Conjugate made up of both the antibody trastuzumab and the cytotoxic deruxtecan. Last year, Enhertu had sales of USD 3.7bn and is expected to reach sales of USD 10bn by 2028, pointing to the huge commercial potential in this patient setting.

Malaria program expanded in 2025

The extensive malaria vaccine program conducted by University of Oxford (UoO) has been further expanded with three studies in planning phase. In total, ExpreS2ion is producing antigen material in ten UoO-studies and is now negotiating an agreement with the Serum Institute of India, holder of commercial rights to the projects.

Fair value trimmed after delay and discontinuation

A cash burn of SEK 23m in Q1 reduced the cash position to SEK 58m, which may fund operations until January next year. The delay caused by slow enrolment in the phase 1 study and the discontinuation of the CMV project led us to reduce fair value to SEK 75 (91).

Our base scenario consists of a licensing deal with ES2B-C001 in 2027, which implies bridge financing in Q4 and a new share issue in 2026 on the back of a phase 1 interim data.