Lactobacillus Plantarum in Preventing Acute Graft Versus Host Disease in Children Undergoing Donor Stem Cell Transplant

This study is looking for children and young adults between the ages of 2 and 25. You would be considered if you have a blood cancer like leukaemia or lymphoma and are planning to have a stem cell transplant from a particular type of donor. This usually means a donor who isn't a perfect match from your immediate family, or an unrelated donor who isn't a perfect match.

There are a few health checks to make sure you're well enough for the study. For example, your doctor will check your general health and how active you are. It's also important that you haven't taken any other special 'good bacteria' (probiotic) supplements in the last month, although eating yoghurt is fine.

You wouldn't be able to join if you're getting stem cells from a perfectly matched family donor, or if you have certain serious gut problems, like a history of severe bowel inflammation or surgery. Pregnant girls also can't take part. The medical team will check all these things carefully to make sure the study is right and safe for you.

If you decide to join this study, you'll be put into one of two groups by chance, like flipping a coin. One group will receive the Lactobacillus plantarum bacteria, and the other group will get a 'placebo' – this looks exactly the same but contains no active ingredients. This is a common way to test if a new treatment works.

Both groups will take their assigned treatment every day. This will start around the time you begin your transplant preparation (chemotherapy or radiotherapy) and continue for about 56 days after your stem cell transplant. You'll take it by mouth, or if you have a feeding tube, it can be given through that. Throughout this time, and at regular check-ups after your transplant, the doctors and nurses will monitor your health very closely. They'll check for any signs of gut problems, take samples (like blood or stool) to see how your body is responding, and track your overall recovery. The full duration of your participation in the study, including follow-up, will be decided by the medical team.