Chemotherapy-based conditioning matches outcomes of total body irradiation for MRD-negative B-ALL
A groundbreaking study has revealed that patients with B-acute lymphoblastic leukemia (B-ALL) who have no detectable remaining cancer cells after prior treatment can achieve similar outcomes with chemotherapy-based conditioning as with the standard total body irradiation (TBI) regimen. This finding could potentially spare many patients from the long-term side effects associated with TBI. The research, conducted using next-generation sequencing (NGS) to identify patients with no measurable residual disease (MRD), marks a significant advancement in the field of leukemia treatment.
The trial, led by Dr. Hisham Abdel-Azim, a renowned expert in transplant/cell therapy and hematological malignancies, aimed to explore the use of chemotherapy-based conditioning in patients with no evidence of MRD. The results showed a two-year relapse-free survival rate comparable to that of patients who received TBI-based conditioning, making it a promising alternative to the traditional approach.
Dr. Abdel-Azim and his team utilized NGS-MRD, a highly sensitive method to detect any remaining leukemia cells, to categorize patients at very low risk of relapse. This approach allowed them to pilot the use of non-TBI-based conditioning, which significantly reduced the need for TBI in MRD-negative patients without compromising their treatment outcomes.
B-ALL, a bone marrow cancer characterized by an overproduction of abnormal B-cells, is the most common type of childhood leukemia and the most prevalent subtype of ALL in adults. Allogeneic hematopoietic cell transplantation is a curative treatment for B-ALL, especially for high-risk patients. However, the pre-transplant conditioning regimen, which includes intensive chemotherapy and radiation, can have detrimental long-term effects on memory, endocrine function, and the risk of subsequent cancers.
The study enrolled 51 MRD-negative patients, with ages ranging from 2 to 30 and a median age of 13.5 years. Half of the participants were male. At the time of transplant, half were in their first complete remission, and the other half were in their second complete remission. The follow-up period has been a median of 2.3 years, with some patients followed for up to six years.
The results demonstrated that 82% of patients who received chemotherapy-based conditioning were alive after just over two years, and 76.3% were alive without relapsing. Only 12% of participants died from non-cancer-related causes, and 12% experienced a relapse. These outcomes were compared to an observational cohort of 151 patients who received the standard TBI conditioning.
Importantly, event-free survival and overall survival were similar in both the TBI and non-TBI groups. This finding suggests that the NGS-MRD test can serve as a valuable biomarker to identify patients who can safely avoid TBI conditioning. Dr. Abdel-Azim emphasized the potential impact of this study, stating that it sets a new standard of care for MRD-negative patients, allowing them to receive non-TBI-based conditioning.
However, the study also noted that younger age at diagnosis and younger age at the time of hematopoietic cell transplantation were associated with inferior outcomes. Among MRD-negative patients, those with high-risk genetic abnormalities had similar outcomes to those with non-high-risk abnormalities. The researchers plan to further investigate genetic factors and other variables to guide treatment decisions based on individual patient risk profiles.
The study was funded by the Gateway for Cancer Research, and the findings were presented by Dr. Abdel-Azim at the Loma Linda University School of Medicine Cancer Center on December 6, 2025. This research opens up exciting possibilities for improving the treatment of B-ALL patients, potentially reducing the long-term side effects associated with traditional TBI conditioning.
