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30 patients, one deleted protein: the trial trying to make blood cancer treatment miss the healthy cells

Qurexa Editorial Team26 September 20265 min read 0 0
30 patients, one deleted protein: the trial trying to make blood cancer treatment miss the healthy cells

What happened

Researchers have published results from a trial that tries to solve an old and frustrating problem in blood cancer treatment. The work was led by Washington University School of Medicine in St Louis, carried out at the Siteman Cancer Center and 14 other sites across the United States and Canada. The results were published in the journal Nature Medicine in September 2026. Here is the problem they were tackling. Some drugs for acute myeloid leukaemia (AML) work by hunting down a protein called CD33 that sits on the surface of the cancer cells. The trouble is that CD33 also sits on healthy blood-making cells. So the drug hits both. The idea in this trial was to change the healthy cells instead of the drug. Before transplanting donor stem cells into patients, the team used CRISPR gene editing to remove CD33 from those donor cells. The edited cells have a long scientific name, tremtelectogene empogeditemcel, shortened to trem-cel. They were developed by the company Vor Biopharma. After the transplant, patients were then given gemtuzumab ozogamicin, the drug that targets CD33. In theory, the drug should find the cancer cells and walk straight past the new, edited, healthy ones. Thirty patients with AML or myelodysplastic syndrome (MDS) took part.

Why this matters

A stem cell transplant is already one of the hardest treatments in medicine. Someone's own bone marrow is wiped out and replaced with cells from a donor. The weeks afterwards are dangerous. The body has very few white blood cells to fight infection, and very few platelets to stop bleeding, until the new cells settle in and start working. Doctors call that settling-in "engraftment". Adding a CD33-targeting drug on top of that has always been a gamble. It might catch leukaemia cells that survived the transplant, but it can also knock down the new graft you just spent months securing. If you can make the graft invisible to the drug, you change that trade-off completely. You could, in principle, give the drug for longer, or at a fuller dose, without paying for it in blood counts. That is a genuinely clever idea, and it is a good example of gene editing being used for something quite unglamorous: not creating a new ability, but removing a label so a treatment stops hitting the wrong target.

What the evidence actually says

This is where care is needed, because early trials are easy to over-read. All 30 patients achieved engraftment by day 28. Platelet production returned by day 16 on average. Those are broadly similar to what you would expect from a standard transplant, which is the point: the editing did not make the transplant itself go worse. During maintenance therapy, patients kept stable blood cell counts. That suggests the edited cells were indeed protected from the drop that usually comes with this kind of drug. Average survival was just over 14 months. Seven of the 30 patients died: four from the cancer progressing, and three from transplant-related complications. Read those last two sentences again, because they are the honest core of the story. This was a small, early trial in people with very serious blood cancers, and a quarter of participants died within the follow-up period. There was also no comparison group. Without a randomised control arm, you cannot say how these 30 patients would have fared under standard care. The study lead, John F. DiPersio, said the team was "encouraged" by the results, and pointed towards combining the approach with other CD33-targeted immunotherapies in future. "Encouraged" is the right word. It is not "proven".

Practical advice

Nothing here changes treatment in the UK today. This is a US and Canadian trial, published in a journal, at an early stage. It is not an approved therapy and it is not available on the NHS. If you or a relative has AML or MDS, and you want to make use of news like this, the useful moves are these. Ask your haematology team whether any trial is open to you. In the UK, ask specifically about the NIHR's Be Part of Research service, which lists studies looking for participants. Ask what genetic and molecular testing has already been done on your cancer. Increasingly, which treatments are options depends on that detail. Be cautious with anything online that promises access to an experimental therapy for a fee. Legitimate trials do not charge participants for the treatment being studied. Keep an eye on the difference between "published in a journal" and "available to patients". The gap is usually measured in years, and some treatments never close it. And if you are supporting someone through a transplant, the practical things still matter most: infection precautions, keeping on top of the medicine schedule, and knowing exactly when to ring the unit rather than wait.

What to know

Researchers used CRISPR to remove the CD33 protein from donor stem cells before transplanting them into 30 patients with AML or MDS, so that a CD33-targeting drug could attack the cancer without destroying the new graft. All 30 patients engrafted by day 28, and platelet production returned by day 16 on average, similar to a standard transplant. Average survival was just over 14 months. Seven patients died: four from cancer progression and three from transplant complications. There was no control group, and the trial was small. This is a promising proof of concept, not a proven treatment. The results were published in Nature Medicine in September 2026 and the approach is not currently available outside research. Sources: Washington University School of Medicine in St Louis via ScienceDaily, "CRISPR could help doctors attack blood cancer without destroying healthy cells", 25 September 2026, https://www.sciencedaily.com/releases/2026/09/260924020408.htm; Nature Medicine, September 2026, https://www.nature.com/nm/; NHS, "Acute myeloid leukaemia", accessed 26 September 2026, https://www.nhs.uk/conditions/acute-myeloid-leukaemia/. This article is for general information and does not replace advice from a doctor, pharmacist or other qualified healthcare professional. Decisions about cancer treatment or joining a clinical trial should be made with your own specialist team.

#CRISPR#leukaemia#stem cell transplant#gene editing#cancer research#clinical trials

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