Affibody has received a recommendation from its Trial Review Committee (TRC) to proceed to the second part of its Phase I trial evaluating the radioligand therapy candidate ABY-271 in those with human epidermal growth factor receptor 2 (HER2)-positive metastatic breast cancer.

The committee’s decision comes after a review of initial cohort patient data on tolerability, dosimetry, safety, and biodistribution.

The TRC, which includes a medical monitor, principal investigators, and specialists in dosimetry and nuclear medicine, assessed data from the first cohort of participants.

It found that the therapy demonstrated targeted tumour activity and a low uptake in kidneys and other vital organs.

Based on these findings, the committee has advised advancing to the next stage of the trial, which will involve testing higher radioactivity levels and additional doses of protein mass.

The therapy is being tested in the open-label, first-in-human, randomised, two-stage, Phase I trial to evaluate its tolerability, safety, and biodistribution in tumours and vital organs in those with HER2-positive metastatic breast cancer.

The trial is being conducted at specialised centres in Germany and Sweden.

Affibody CEO David Bejker said: “I am thrilled that these early clinical results with ABY-271 mirror the preclinical findings and dosimetry predictions remarkably well. I am especially excited about the low kidney uptake.

“The positive outcome not only marks an important milestone for this programme but also for the Affibody platform as a powerful technology for developing next-generation targeted radiotherapeutics.”

The Phase I trial is structured in two parts. Part A involves up to six sequentially enrolled patients to evaluate the uptake of the therapy in tumours and critical organs.

Part B will expand the study to 15 randomised subjects, assessing higher radioactivity levels and additional protein mass doses.

In both phases, patients receive a single intravenous infusion of the therapy.

Affibody plans a protocol amendment submission to the European Medicines Agency (EMA) to expedite the transition to the second part of the trial.

It anticipates beginning the next phase in the first half of 2026, with outcomes expected in the second half.

Dr Oscar Wiklander at Karolinska University Hospital serves as the coordinating investigator in Sweden.