Sesen Bio, Inc. is a clinical-stage biotechnology firm deeply involved in the creation, advancement, and eventual market launch of targeted fusion protein therapeutics (TFPTs). Their primary aim is to combat various forms of cancer. Their flagship experimental drug, Vicineum, is a locally administered targeted fusion protein currently undergoing Phase III clinical trials. It targets several conditions, including non-muscle invasive bladder cancer that has not responded to bacillus Calmette-Guérin (BCG) treatment, non-muscle invasive carcinoma in situ of the bladder in patients who previously received BCG, and squamous cell carcinoma affecting the head and neck region. Another promising candidate, VB6-845d, is being developed to address a range of anti-epithelial cell adhesion molecule-positive solid tumors. Sesen Bio is also collaborating with Leiden University Medical Center on the joint development of an imaging agent. Originally incorporated in 2008, the company operated as Eleven Biotherapeutics, Inc. before rebranding as Sesen Bio, Inc. in May 2018. Its corporate headquarters are situated in Cambridge, Massachusetts.