When a stem cell transplant is needed to treat leukaemia or other blood cancers, a donor with a good genetic match must be found.
New technique to grow stem cells for transplant promises faster recovery for blood cancer patients.
By Rosnah Ahmad
When a stem cell transplant is needed to treat leukaemia or other blood cancers, a donor with a good genetic match must be found.
Blood-forming stem cells have to be taken from either the donor’s bone marrow or peripheral blood for transplant. But the chance of finding a fully matched, unrelated donor is slim – and the next best hope is to turn to cord blood stem cells, which don’t have to be a perfect match. Using stem cells from a newborn baby’s placenta and umbilical cord has a major limitation as each cord blood unit contains only a small amount of stem cells. Two units of cord blood are usually needed for adult patients suffering from blood cancers.
Now, a new technique – Nicord® cord blood expansion – aims to overcome this limitation by taking a single unit of cord blood, and then culturing and growing the stem cells in the laboratory for transplant.
Describing cord blood expansion as “game-changing technology”, Associate Professor William Hwang, Senior Consultant, Department of Haematology, Singapore General Hospital (SGH), and Medical Director, National Cancer Centre Singapore (NCCS), said: “By growing or expanding 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.
“Basically, cord blood transplant is part of our attempts to meet the needs of those patients who cannot find a perfect match.”
In preparation for a transplant, patients undergo a high dose of chemotherapy, which lowers their infection-fighting white blood cells to near zero. They then receive an infusion of the expanded stem cells. “It’s like a garden with abnormal plants and weeds. Sometimes you need to clear everything in order to start afresh. That’s what a transplant is all about,” said Prof Hwang.
Until the transplanted cells are grafted, or start to grow, the patient is very prone to infections. An indicator of success of the transplant is the time required for the patient’s white blood cell count to recover – that is, for engraftment of the transplanted cells.
According to Prof Hwang, a trial of the Nicord® technique found that engraftment took around 11 days versus the average 24 to 26 days with standard cord blood transplants.
New blood and immune system cells were able to grow and multiply quickly – meaning patients were less prone to infections. They were also discharged from hospital earlier as a result.
With the new technique, fewer than 10 per cent of patients died, Prof Hwang said, compared to the more than 30 per cent mortality rate for those undergoing a conventional cord blood transplant.
However, the long-term survival prospects of patients who undergo the technique are unclear as no data are yet available. The Nicord® technique is now undergoing a phase 3 multicentre trial, which aims to recruit 120 patients, and is expected to be completed by December 2019.
With the Nicord® clinical trials showing the potential that such expansion techniques has in treating blood cancers, Prof Hwang is working with a multidisciplinary team of researchers from NCCS, Duke-NUS Medical School and the National University of Singapore to develop a novel method for expanding the blood-forming stem cells in umbilical cord blood in Singapore. Nicord® is a product of Gamida Cell of the US.
At SGH, more than 80 stem cell transplants are performed yearly on average, with four of them being cord blood transplants.
THIS ARTICLE WAS FIRST PUBLISHED IN SINGAPORE HEALTH NOVEMBER/DECEMBER 2018.
