Both immune suppressive therapy (IST) and bone marrow transplant (BMT) are potentially curative for severe aplastic anemia (SAA). Currently BMT is the therapy of choice for young patients who have a matched sibling or other family donor; IST is the alternative for those who do not. If IST fails to halt the disease — or the disease recurs, or the patient develops leukemia or another worse disease — matched unrelated donor (MUD) BMT is employed as the secondary treatment.
But how would MUD BMT compare with IST as the first treatment for patients who do not have a matched related donor? A phase 3 randomized trial is comparing the two different approaches in SAA patients up to 25 years old, using standard-of-care drugs. The study, “A Trial Comparing Unrelated Donor BMT with IST for Pediatric and Young Adult Patients with Severe Aplastic Anemia (NCT05600426),” is enrolling 234 patients at 15 centers, including Roswell Park, where Nataliya Buxbaum, MD, Department of Pediatric Oncology, serves as site principal investigator.
The rationale for the clinical trial is based on the results of a consortium study involving 314 pediatric patients treated for SAA between 2002-2014 (Rogers et al., Haematologica, 2019). The study found that approximately 70% of those enrolled responded to IST.
“However, a significant proportion of those patients ended up needing additional treatment due to relapse or malignant transformation or clonal abnormalities,” Dr. Buxbaum notes. “For relapsed or refractory SAA, hematopoietic cell transplant (BMT) as a secondary treatment was associated with better outcomes than repeated IST.” The cited article reported that more than 80% of the patients who underwent BMT experienced event-free survival at three years following treatment, compared with less than 60% of the patients who were treated with IST.
This clinical trial hopes to expand on that approach by comparing failure-free survival when either IST or MUD BMT is used as the first treatment for patients who do not have a suitable fully matched related donor but do have at least two well-matched unrelated donors. Half the patients in this two-arm study will receive IST and half will undergo matched unrelated donor transplant of hematopoietic stem cells.