I spent yesterday at the celebration in London of the Kings College Hospital's one thousandth stem cell transplant. Although not rivalling Seattle, it is an stupendous achievement - remember that the population of America is 5 times greater than that of Britain. Such is the increasing popularity or transplantation that about half of those transplants have taken place in the past 5 years.
It was an interesting day during which we not only learned about the growing edge science with lectures and cancer stem cells, regulatory T cells, the GVL effect, and post-transplant immunotherapy, but also about the logistical problems of finding donors, and the organization of funding, commissioning services and monitoring outcomes. There were also two patients who detailed their experiences of transplants. One of them, a man without arms or legs because of a congenital abnormality, was a real comedian.
What interested me most was the talk on cord-blood transplants, by Vanderson Rocha from Paris, who did the first cord blood transplant. It is people from ethnic minorities who are likely to seek a cord transplant, since it is so difficult to find a match from donor panels. Those of mixed race make things particularly difficult. Although there are immense opportunities in cord blood, principally because you don't need a complete match for the graft to be successful, cord blood has its own specific difficulties. First there is the volume required - most cords don't have enough stem cells for an adult transplant. Interestingly the highest yields come from the longest labors; usually first births. Cesarean sections cut down on the yield. Because of this double cords have been used, but only one cord grows, the other provides accessory cells that help expand the other one. There is a high rate of graft failure - about 10%. Also the T cells that derive from the cord are naive - they have no immunity against common viruses such as CMV or adenovirus. A cord blood recipient could die from the common cold.
Although many units are keen to jump on the cord blood bandwagon, it remains an experimental treatment. A lot more work needs to be done before it can be regarded as routine.
For CLL patients transplantation remains a major risk. Such patients are already susceptible to the sorts of infections that cause the early transplant related mortality and become doubly vulnerable following a transplant. With reduced intensity commissioning, some tumors have a TRM of less than 10%; for CLL it remains stubbornly over 20% even in the best centers.