Allogeneic stem cell transplantation

Allogeneic stem cell transplantation is in many ways similar to autologous stem cell transplantation. The only difference is that the patient is not receiving his own stem cells, but those of a donor. Since each human being carries a unique pattern of molecules on the surface of all cells it is important for any type of transplantation that the immune system of the donor and recipient (patient) match as closely as possible in order to avoid rejection of the foreign stem cells (or organ). The greatest success is achieved with allogeneic transplantation of stem cells if the donor is a close relative or even an identical twin.

Allogeneic stem cell transplantation is most commonly used to treat patients with acute myeloid leukemia (AML), but also other forms of leukemia. Since the immune system between donor and recipient (patient) never matches exactly (except in the case of identical twins) this form of transplantation is often (up to 50%) associated with reactions of the patient’s (recipient) immune system against the transplanted stem cells from the donor (graft versus host disease, GvHD). This chronic disease affects many different organs resulting in their malfunction and often requires the use of immunosuppressant drugs.

In allogeneic stem cell transplantation the harvesting of stem cells must be very safe for the healthy donor not causing any harm or disease. Standard treatment is currently performed by pharmacological mobilization of stem cells with G-CSF and subsequent collection from the blood by apheresis. The use of CXCR4 antagonists, like POL6326, for mobilization may provide distinct advantages compared to G-CSF due to differences in the subset of stem cells being mobilized and opens the possibility of reducing the rate of GvHD in this setting. But this clearly warrants future long term clinical studies.