German pharma Merck KGaA has gained an option to five bispecific antibodies developed at F-Star Biotechnology. The deal will provide Cambridge, UK–based F-Star with up to $129.5 million over two years, including an upfront payment, R&D funding and milestones. It includes rights to F-Star's lead immuno-oncology asset, FS118, which is designed to block LAG-3 (lymphocyte-activation gene 3) and PD-L1 (programmed death-ligand 1), two pathways commonly used by cancer cells to evade the immune system. FS118 is currently in preclinical testing. Merck, which is headquartered in Darmstadt, can select up to four additional, discovery-stage antibodies under the agreement. F-star will be responsible for preclinical and clinical development of each of the antibodies until Merck exercises its option, which could be worth an additional $1 billion if the company chooses to acquire all five programs. F-Star applies its modular antibody technology platform to develop bispecific antibodies. The platform introduces a novel antigen-binding site into the constant (Fc) region of an antibody to create an Fc domain with antigen binding activity. The resulting structure becomes a building block for combining with other drug formats, for example, with a variable region of an existing antibody to generate a bispecific antibody. Merck already has a bifunctional antibody, M7824, against PD-L1 and transforming growth factor β in phase 1 testing. Its anti-PD-L1 antibody Bavencio (avelumab), developed with New York–based partner Pfizer, was granted accelerated approvals in the US in 2017 to treat locally advanced or metastatic urothelial carcinoma and Merkel cell carcinoma.