The transferred stem cells repopulate the bone marrow with new blood cells that create a new immune system. Research has shown this new immune system often plays a key role in killing any residual cancer left in the bone marrow after the chemotherapy. But side effects of standard allogeneic transplants are significant. Patients who undergo this procedure are typically hospitalized for weeks to months. Many patients die from complications of the transplant procedure, Frohlich said.
Recent research suggests that stem cells can engraft with much less toxic preparative regimens.
In this newer approach, the goal is to allow the transferred immune system to deliver the anticancer effect, rather than the chemotherapy. In the UCSF trials, Frohlich and Sayre plan to deliver the treatment on an outpatient basis. Patients will be hospitalized only if complications arise. The donor is connected intravenously to a machine that collects the blood cells and returns the remainder of the blood to the donor. Prior to transfer of these cells to the patient by infusion, the patient is treated with a low dose of total body irradiation and special medications to prevent his or her immune system from rejecting the transferred cells.