Affibody AB announced that the Trial Review Committee (TRC) has recommended to advance the Phase I clinical study with the Radioligand Therapy (RLT) candidate ABY-271 in HER2-positive metastatic breast cancer to its second part, where higher radioactivity levels will be evaluated. 

The TRC has based its positive recommendation on safety, tolerability, dosimetry and biodistribution data from the first enrolled cohort of patients, demonstrating tumor targeting and a favorable safety profile with low uptake in kidneys and other critical organs.

"The initial data from the ABY-271 study are very promising. We observed a favorable safety profile and encouraging biodistribution data, supporting progression of the study to the next stage," said assistant professor Oscar Wiklander at the Karolinska University Hospital, coordinating investigator in the study. "These results offer important insight into how the therapy behaves in patients, and we are eager to advance the study to deepen our understanding of its clinical potential."

"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," said David Bejker, CEO of Affibody. "The positive outcome not only marks an important milestone for this program but also for the Affibody^® platform as a powerful technology for developing next-generation targeted radiotherapeutics."

ABY-271 is an Affibody^® molecule that targets HER2-expressing tumors and is labeled with the radioisotope lutetium-177, which emits cytotoxic beta radiation exerting irreversible damage to the tumor cells. Affibody is evaluating ABY-271 in a first-in-human, open-label, two-stage, randomized Phase 1 clinical study to assess the safety, tolerability, and biodistribution of ABY-271 in tumors and critical organs in subjects with HER2-positive metastatic breast cancer. The study is conducted at sites specialized in breast cancer and nuclear medicine in Sweden and Germany.

The TRC, including principal investigators, medical monitor, dosimetry and nuclear medicine specialists, has reviewed safety, tolerability, dosimetry and biodistribution data from a pre-specified number of enrolled patients. The TRC confirmed favorable safety and biodistribution, with low uptake in kidneys and other critical organs. The TRC recommends advancing the study to part B, which will evaluate higher radioactivity levels and additional protein mass doses. In line with this recommendation, Affibody will submit a protocol amendment to the European Medicines Agency (EMA) to accelerate the transition to the second part, which is expected to start in H1 2026 with the first results anticipated in H2 2026.