4-Antibody AG

The company's core technology was the proprietary in-vitro Retrocyte Display®, a high-throughput platform for the rapid discovery and optimization of fully-human antibodies. This technology utilized a flow cytometry approach with full-length IgG format human antibody libraries expressed in mammalian B cells, which are naturally suited for optimal antibody display. This process was designed to be a fast and efficient source of high-quality therapeutic antibody drug candidates. One of the company's lead development products was an anti-cytomegalovirus antibody drug.

In January 2014, Agenus Inc., a US-based biotechnology company, announced a definitive agreement to acquire 4-Antibody AG. The deal was valued at an initial $10 million in Agenus common stock, with potential additional payments exceeding $40 million based on achieving certain milestones. The acquisition was completed in February 2014. Agenus's stated intention was to retain 4-Antibody's operations and management team, including CEO Dr. Robert Burns. The acquisition provided Agenus with multiple preclinical immune checkpoint antibody programs, including those targeting GITR and OX40.