Newco Yellowstone Biosciences Ltd. has been formed to develop soluble bispecific T-cell receptors against a novel class of tumor-specific antigens it has discovered in leukemia patients who were cured by a donor stem cell transplant. The company has proprietary access to a biobank of over 10,000 samples from more than 3,000 acute myeloid leukemia (AML) patients. A small number of these patients were cured by an allogeneic bone marrow transplant, whilst unusually, having no sign of graft-vs.-host disease.