A breakthrough technology developed in Switzerland could drastically reduce the number of animals needed for safety testing of therapeutic antibodies.

Antibodies are proteins produced by the immune system to help fight infections or target diseases. These proteins make up more than half of the recently approved medicines known as biopharmaceuticals – drugs derived from biological sources.

Before each of these therapeutic antibodies can be tested in humans, rigorous studies in animals are required to assess their safety, effectiveness, and behaviour in the body. However, currently, scientists can only test up to four active ingredients – the substances in drugs that produce the intended effects – in a single animal study.

Researchers at EARA member the University of Zurich (UZH), have now developed an innovative approach called Flycode technology, which allows up to 25 different antibodies to be tested simultaneously in a single mouse.

Flycodes are small protein fragments linked to antibodies, that function like barcodes to tag each individual drug candidate. This allows each candidate to be tracked and analysed separately – the technology also does not interfere with the antibodies’ effectiveness in a living organism.

To demonstrate the potential of Flycode, the UZH team tested 80 drug-like synthetic biomolecules – known as sybodies. They successfully gathered data on how these drugs travel through the body and how long they remain active, using just 18 mice—representing a 100-fold reduction in the number of animals typically required for such studies.

“We get much more data with fewer mice, and the data is of better quality because the analyses can be directly compared,” said Markus Seeger, lead author of the study published in PNAS.