Australasian-led Clinical Trial In Stem Cell Transplant For Blood Cancers Set To Change 40 Years Of Standard Practice

Leading Australian and New Zealand researchers have demonstrated that the use of a new, less toxic drug combination after stem cell transplants for leukaemia significantly improves patient outcomes post-transplant, reducing the risk of the life-threatening complication of Graft Versus Host Disease (GVHD).

The BM12 CAST trial, a major clinical trial led by the Australasian Leukaemia & Lymphoma Group (ALLG) across New Zealand and Australian hospitals, will transform global blood stem cell transplant outcomes for people with high-risk blood cancers like leukaemia.

“This new treatment triples the chances of a patient being alive, healthy and free of GVHD three years after stem cell transplant,” said lead ALLG BM12 researcher, Professor David Curtis, Clinical Haematologist and senior bone marrow transplant physician at The Alfred and Director of Malignant Haematology Research at the Australian Centre for Blood Diseases, Monash University.

Blood stem cell transplants are often lifesaving for leukaemia patients, but they come with a high risk of life-threatening complications, especially in the first 100 days after transplant. Common side effects include infections, organ damage, and the often-debilitating Graft versus Host Disease (GVHD), an irreversible lifelong complication.

“The BM12 trial showed the new treatment combination is simple, safe and more effective than current methods in preventing GVHD, which contributes to death or life-long illness in 20% of patients undergoing a blood stem cell transplant,” said Prof Curtis.

Results of BM12 trial were published in the New England Journal of Medicine and presented at the European Hematology Association 2025 Meeting in Milan, Italy.

These results are game-changing for stem cell transplant patients, with cyclosporin and cyclophosphamide offering a new standard of care for prevention of GVHD for patients with aggressive blood cancers undergoing transplant from a matched related blood stem cell donor.

Researchers compared the standard drug combination used for the last 40 years with a new combination of cyclophosphamide and cyclosporin, for leukaemia patients. The new drug combination tripled the number of patients that were alive, cured of the blood cancer and not suffering from GVHD three years after transplant (49.1% vs 14.2% for the standard drug combination). The risk of serious side effects also dropped from 32.4% to 19.7%.

The trial’s success has immediate implications for clinical practice in the management of blood stem cell transplants. The simplicity and effectiveness of the new treatment, along with reduced toxicity and improved patient outcomes, will become the new standard of care in GVHD prevention for matched sibling transplants.

The ALLG BM12 CAST trial’s success is particularly important for patients such as Gladys Borgueta, who was diagnosed with Acute Myeloid Leukaemia (AML) and admitted to Auckland Hospital’s Motutapu Ward in May 2021.

“Nothing prepares you for an unexpected diagnosis like acute myeloid leukaemia, everything else becomes a blur and your world is turned upside down. Nothing prepares you for the months, weeks in hospital and sometimes in isolation,” said Gladys.

ALLG researcher, haematologist Dr Clinton Lewis and colleagues from Auckland Hospital, met with Gladys and suggested the ALLG BM12 trial.

“I knew that the team around me would give me the best care possible. I had however no high expectations just because this was a trial, it could go either way,” Gladys said.

Gladys was allocated to the new treatment arm of the BM12 clinical trial and received a stem cell transplant in January 2022. The new drug combination meant that her transplant was successful and she avoided serious side effects such as GVHD.

Three years on, Gladys continues to do well after her transplant and is in remission from her leukaemia.

“Without research, I would not have, or for that matter any other patient, benefited from the treatment I got. I feel grateful and blessed to be given a second chance at life.”

Auckland Hospital lead investigator, Dr Clinton Lewis, said, “The results of this exciting study are already changing practice in New Zealand and will continue to improve the lives of cancer patients receiving allogeneic stem cell transplants.”

“Our options for treating Graft versus Host Disease in New Zealand remain very limited compared to other countries, so preventing this complication is incredibly important for our patients.”

“This study shows that we can help our patients live better lives, free of their cancer and GVHD, when we utilise this treatment approach. This sets an improved standard of care in New Zealand”, said Dr Lewis.

The BM12 CAST trial was funded by the Australian Government’s Medical Research Future Fund, the Auckland Medical Research Fund and the Cancer Society of New Zealand.

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