Regulatory Protein May Improve Stem Cell Transplants

Researchers have discovered that a T cell regulatory protein may reduce the incidence or severity of graft vs host disease (GVHD) in patients receiving a stem cell transplant from a genetically mismatched donor.

Stem cell transplantation is a potential cure for hematopoeitic cancers such as leukemia, myeloma, and lymphoma. However, GVHD has a historical incidence of nearly 100% in the absence of a genetic match between transplant donor and recipient. Prevention of GVHD would substantially reduce the morbidity and mortality of stem cell transplantation and would allow it to be applied to numerous malignant and genetic disorders.

Researchers at Repligen Corp. (Needham, MA, USA) are developing a soluble form of the protein, called CTLA4 (CTLA4-Ig). They believe it has the potential to inactivate only those cells that are initializing an unwanted immune response, without compromising the body's ability to fight off infections. Furthermore, CTLA4-Ig may educate the immune system with only a brief treatment, permanently disabling the specified cells from any unwanted future attack. In a phase 1 trial, CTLA4-Ig prevented the development of GVHD in eight of 11 evaluable patients receiving a stem cell transplant for leukemia or other hematopoeitic malignancies. The company is now initiating a phase II clinical trial.

"Expansion of the donor pool to mismatched family members would substantially reduce the cost of a stem cell transplant and eliminate treatment delays inherent in the search for a matched donor,” said Walter C. Herlihy, Ph.D., president and CEO of Repligen.