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Is the youngest donor always the best choice for BMT?

An observational research study offers insights into the impact of donor age on BMT

A patient who needs a blood or marrow transplant (BMT) has more than one 8/8 human leukocyte antigen (HLA)-matched unrelated donor (MUD) option. Should the youngest donor be the top choice? And do other donor characteristics impact outcomes for patients who receive an 8/8 MUD transplant?

That’s what researchers from the CIBMTR®—a research collaboration between the Medical College of Wisconsin and NMDPSM—aimed to better understand.

The answers are important. Patients who need BMT for a cancerous or non-cancerous disease would have a higher likelihood of having an available optimal donor if the donor choice is expanded beyond the youngest donors.

What the researchers investigated

An earlier study defined the best donor as the youngest donor available on a search of the NMDP Registry SM. However, that study only looked at overall survival (OS) at <1 year after BMT.

This study looked at OS and event-free survival (EFS) for up to 3 years after BMT. EFS included survival without:

  • Relapse (the disease coming back)
  • Graft failure or rejection (the patient’s body did not accept the donor’s cells)
  • Moderate or severe graft-versus-host disease (a complication after BMT where the donor’s cells attack the patient’s healthy cells)

The researchers used an advanced machine learning technique to better understand how 8/8 MUDs should be prioritized based on more donor characteristics, such as age, gender, prior pregnancy, cytomegalovirus (CMV) status or extended HLA matching (HLA-DQB1 and DPB1).

They analyzed data from more than 11,800 first 8/8 MUD transplants performed in the U.S. and reported to the CIBMTR from 2016 through 2019. They also analyzed data from a subset of 699 patients who had detailed search data available in the NMDP Search Archive.

What the study found

The study revealed only donor age and donor gender had clinically important impacts on outcomes.

Donor age was important for OS. There was a clinically meaningful increase in OS (greater than 1%) when an 18-year-old donor was used compared to a donor 34 years old and older.

But importantly, the researchers found that the optimal MUD donor age could range between 18 and 30 with a minimal impact to patient outcomes.

Donor gender had only a limited impact on OS, but it was important for EFS. Male donors were preferred when the age difference between a male and female donor was minimal. This could allow for nuanced donor selection that prioritizes OS but considers EFS if OS differences are marginal.

Researchers from the CIBMTR presented the study results as a poster at the 65th ASH Annual Meeting & Exposition in December 2023.

What this means for patients

The study is important because it demonstrates donors aged 18 to 30 years old result in similar outcomes. This provides more flexibility in donor selection.

By expanding the donor choice beyond the youngest donors, it increases the likelihood a patient will have an available optimal donor for BMT.

Read the clinical summary

View the infographic