Youer than you: An update on the Haploidentical Transplant Research Project

September 4, 2023
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Advances in haploidentical transplant research. Pictured here are vials of blood in a lab, some with red lids some with lilac coloured lids

Youer than You: we love to be individuals!

We all like to think of ourselves as unique, as being a “one off”. Even Dr Seuss celebrated our individuality in his famous line “There is no one alive who is youer than you.” We love to think that we are little pieces of individuality with our own special gifts to bring to the world.

Until, that is, you find yourself needing a bone marrow transplant. Then you desperately want to be similar enough to someone else that you’re a match for bone marrow or stem cell transplant.

But what if you can’t find a close enough match? What then?

Self v. Non-self and the role of HLA

The role of our immune system is to keep our bodies safe. It does this by being able to recognise what is “self” and what is “non-self”, or what is you and what is not. The cells in our immune system use Human Leukocyte Antigens (or HLA) as a way of recognising whether another cell is “self” or “non-self”. The word “human” is self-explanatory. “Leukocytes” are white blood cells, and “antigens” are anything on the outside of cells that the immune system can recognise as foreign or not, self or non-self. HLA molecules are on the outside of every single cell of the body (except for red blood cells).

If you ever need a bone marrow transplant, it is the HLA (the markers that make your cells recognizably ‘you’) that need to be matched in order for the bone marrow transplant to succeed. Many people will be able to find a match through a donor registry, but what about people who can’t find a suitably matched donor? That’s when you might consider a Haploidentical Transplant.

Haploidentical Transplants

For people who can’t find a suitably matched bone marrow or stem cell donor, a half-matched or haploidentical stem cell transplant with a stem cell donation from a half-matched family member may be a possibility. Early attempts at haploidentical stem cell transplants had higher rates of complications for patients due to the less than ideal match between donor and recipient, but the work of dedicated researchers like Associate Professor John Moore and his team at St Vincent’s Hospital has changed that.

Their research focuses on improving the success of haploidentical allogeneic stem cell transplants which could provide a successful treatment option for the 70% of patients per year who require a stem cell transplant but do not have a sibling match.

The first phase of this project was funded by Arrow in 2015 and saw encouraging results and improvements in survival rates for haploidentical transplant patients. Moving into the second phase of the project the trial, with funding through Arrow and the Leukathon, they have evaluated the safety and efficacy of changes to the drug regimen used to manage post transplant care for patients who have received a haploidentical stem cell transplant, with a paper recently published in the journal Blood Advances a journal of the American Hematology Society, with the study demonstrating a 72-74% survival rate two years post transplant.

The next phase of the project will involve multiple sites (St Vincent’s Hospital in Sydney, Westmead Hospital in Sydney, and Fiona Stanley Hospital in Perth) and will investigate changes in pre-transplant conditioning regimens to optimise outcomes for patients having a haploidentical stem cell transplant. In addition to the medical trials, the research team will seek to quantify the costs of this treatment to both patients and the public purse through an in-depth economic analysis. This phase of the study is currently under review by the Human Ethics Committee, and will hopefully commence soon.

We eagerly anticipate the outcomes of this next phase of the research. Successful outcomes in this project could lead to greater hope and improved outcomes for people with no matched donor. Once again we thank the Leukathon for their amazing fundraising efforts and Dr John Moore and the team at St Vincent’s Hospital and the other participating centres for their incredible work in researching better treatments for patients.