When Ms Judith Chew underwent a cord blood stem cell transplant a year ago (May 2017) as part of treatment for acute myeloid leukaemia (AML), she stayed just a month recovering at Singapore General Hospital (SGH) – about half the usual time that patients undergoing cord blood transplants remain in hospital after transplant.
This was due to a new technique which expands umbilical cord stem cells which allowed Ms Chew’s body to accept the donor cells earlier than with conventional cord blood transplants. New blood and immune system cells were able to grow and multiply quickly and, as a result, she was also less prone to infections.
“This technique, which is now going into phase three of clinical trials, could help improve the results of cord blood transplants for patients who need a bone marrow transplant but do not have a matching donor.” said Associate Professor William Hwang, Senior Consultant, Department of Haematology, SGH and Medical Director, National Cancer Centre Singapore.
Stem cell transplants are performed with stem cells from donated bone marrow, peripheral blood, or cord blood. This is used to treat many patients with blood cancers like leukemia as well as other disorders. When using stem cells from bone marrow or peripheral blood, an exact match from the donor is crucial for the transplant to work. This is often difficult to find as there is a 1-in-4 chance of a suitable match among siblings and 1-in-20,000 from an unrelated donor.
With cord blood, an exact match isn’t necessary, which widens the potential pool of donors. But two units are needed for transplant because of the small amount of blood found in each cord blood unit.
The new technique overcomes this limitation by taking a single unit of cord blood, and then culturing and growing the cells in the laboratory for transplant, said Professor Hwang.
“By growing or expanding the cord blood cells using this new technique, a single cord blood unit is enough to produce a sufficiently high cell dose that offers hope for a successful transplant in an adult,” he said. “Patients also do better and recover much faster.”
Ms Chew is the first patient in Asia to undergo a stem cell transplant using the Nicord® cord blood expansion technique, offered under a global clinical trial by SGH’s Department of Haematology and the Duke University Medical Centre, USA. The results of the trial were presented at the American Society of Haematology 59th Annual Meeting and Exposition in December 2017.
According to the trial results, using this method not only preserves the limited number of donated cord blood units available, it was also found to be superior over the conventional two-unit cord blood transplant in several ways, including better survival and the reducing the time for recovery of blood counts as well as the duration of hospital stay.
In preparation for a stem cell transplant, patients undergo chemotherapy which lowers their white blood cell count to lower than 100 cells per microlitre. A normal white blood count is 4,000 to 10,000 cells per microlitre. That level drops further following a transplant.
It usually takes about 21 to 26 days after a transplant for white blood cell engraftment (the time for the neutrophils in the white blood cells to increase to more than 500 cells per microliter), and during that time, patients become prone to infections, which can complicate their recovery. However, for Ms Chew, it took less than two weeks or 13 days. Given the potential that such expansion techniques has for treating AML, Prof Hwang is also working with a multi-disciplinary team of researchers from the National Cancer Centre Singapore, Duke-NUS Medical School and National University of Singapore to develop a novel method for expanding the blood-forming stem cells in umbilical cord blood in Singapore.
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