ABY-271 & tezatabep matraxetan

Targeted radiotherapies for tumor diseases

In oncology, Affibody is developing a pipeline of novel targeted radiopharmaceuticals. Affibody^® molecules can be attached to radioactive agents. This makes it possible to tailor targeting molecules that, within minutes of being injected into the body, find and bind to a selected surface protein on tumor cells, where they remain for an extended period of time, allowing the radioactive agent to emit its radiation with high precision.

The radiation induces damage to the DNA of the tumor cells, leading to their death. As an added effect, the treatment causes antigen release from the irradiated tumor cells, helping the body’s immune system to raise an immune response to these tumor antigens to detect and kill surviving cancer cells. This mechanism opens interesting possibilities for combination therapies with immuno-oncology drugs or drugs that inhibit DNA repair (e.g. PARP inhibitors). By combining diagnostic and therapeutic radiopharmaceuticals, Affibody’s technology has potential to benefit patients across their entire medical journey.

ABY-271

ABY-271 is a radiotherapeutic candidate aimed at tumor cells that express HER2, regardless of their position in the body. HER2 is a receptor protein overexpressed in several different cancer forms, e.g., breast cancer and gastric or gastroesophageal junction cancer. The project builds on previous clinical research insights from the development of tezatabep matraxetan (ABY-025), showing that the candidate substance can bind to HER2 independently of the tumor origin. ABY-271 with the radioisotope lutetium-177 emits cytotoxic beta radiation, exerting irreversible damage to the cancer cells upon binding.

Preclinical studies in tumor models indicate that ABY-271 may offer a strong therapeutic effect and improved survival rates compared to standard treatments.

The Clinical Trial Application (CTA) for a first-in-human trial in patients with HER2-positive metastatic breast cancer was submitted to the European Medicines Agency (EMA) in December, 2024. CTA approval was received in April 2025 and the first results from the study are expected during 2025.

Tezatabep matraxetan and GE-226

Tezatabep matraxetan (ABY-025) is a Gallium-68-labeled PET tracer candidate that aims to enable non-invasive and cost-effective PET imaging diagnosis of HER2 expression in cancer patients.

Affibody is collaborating with internationally acknowledged academic institutions to explore the clinical utility of tezatabep matraxetan, which is currently being evaluated in investigator-initi­ated studies in Sweden, Poland, and Thailand. Phase 2 results with tezatabep matraxetan indicate that the compound can be used both to detect HER2 expression and monitor therapy response.

In recent years, the interest has increased in treating patients with low HER2 expression and Affibody has successfully shown that it is possible to identify patients with low HER2 expression with ABY-025. Results from a clinical trial demonstrating this have been published in the Journal of Nuclear Medicine (JNM) in May 2024.

To enable a broad market uptake and address the two most important radioisotopes used for PET imaging, Gallium-68 and Fluorine-18, Affibody is collaborating with GE Healthcare, one of the world’s largest medtech companies. GE Healthcare has successfully completed a clinical study in metastatic breast cancer patients and is planning additional clinical studies with GE-226, a Fluorine-18-labeled PET tracer candidate based on the same HER2 targeting Affibody^® molecule as tezatabep matraxetan.