Drs Paul Veys & Persis Amrolia, Gt Ormond Street Hospital

Children undergoing stem cell transplantation must endure powerful chemotherapy and/or radiotherapy treatment to destroy their own bone marrow and create space for the donated stem cells. This process is known as conditioning.

Unfortunately the conditioning treatments can damage the patient’s other organs, causing life-threatening side-effects. Drs Veys and Amrolia set out to develop a new way of destroying the patient’s marrow, by using an antibody that recognises bone marrow cells and linking it to a toxin which will kill them.

Because this “immunotoxin” binds only to marrow cells the team hypothesised that it should kill them specifically, without causing damage to other tissues.

The team identified an antibody specific for stem cells (anti-CD34) and successfully managed to attach a toxin (ricin) to this antibody, creating an immunotoxin, CD34-IT.

Although the team found that the immunotoxin bound to the correct cells, it failed to kill them because it remained on the surface of the cells where the toxin could have no effect rather than being internalised.

They were unable to find a way to address this problem and have concluded that “CD34-IT is unlikely to be of use in pre-stem cell transplant conditioning regimes”.

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