Imagine a breakthrough that could change the lives of young cancer patients forever—reducing harsh treatments without sacrificing success!
That's the exciting promise from a groundbreaking study on children and young adults battling B-cell acute lymphoblastic leukemia (B-ALL). Researchers have discovered that skipping total body irradiation (TBI) in preparation for stem cell transplants doesn't hurt the chances of beating the disease, and the results are on par with traditional methods that include this intense radiation. But here's where it gets controversial—could this mean we're finally moving away from more aggressive therapies that come with lifelong risks? Let's dive into the details of this eye-opening research presented at the 2025 American Society of Hematology Annual Meeting and Exposition.
The study, known as the phase 2 EndRAD trial (NCT03509961), focused on patients with B-ALL who tested negative for minimal residual disease (MRD) through next-generation sequencing (NGS) before their transplant. Minimal residual disease, or MRD, is like tiny traces of cancer cells that might still be lurking after treatment—detecting them helps doctors know if a patient is truly in remission. By removing TBI from the conditioning regimen, the team showed that efficacy stayed strong, matching results from past studies that used TBI.
Specifically, after two years, the event-free survival (EFS) rate—meaning the time without the cancer coming back or other major issues—was an impressive 76.3% (with a confidence interval of 61.1% to 86.1%). Overall survival (OS), which tracks how many patients are still alive, hit 82.0% (confidence interval 67.1% to 90.6%). These numbers met the trial's main goal for EFS, proving that non-TBI approaches could be just as effective.
And this is the part most people miss: doctors can now confidently offer less intense options to eligible young patients. “Based on this evidence, we can recommend non-TBI regimens for pediatric and young adult patients who are bone marrow NGS MRD-negative when they're deciding on their treatment path,” explained Hisham Abdel-Azim, MD, who leads Transplant and Cellular Therapy at Loma Linda University Health, during his talk.
The trial included 202 participants across the board. The key treatment group (51 patients) received a non-TBI, myeloablative conditioning—meaning a high-intensity prep to destroy cancer cells in the bone marrow—followed by an allogeneic hematopoietic cell transplant (HCT). This is a procedure where stem cells from a donor replace the patient's bone marrow to fight leukemia. About 86% of these patients got a combo of busulfan, fludarabine, and thiopeta (a chemotherapy drug). The rest received similar mixes, like fludarabine with melphalan and thiopeta (6%), or added clofarabine (another 6%). The other group (151 patients) was observational, meaning they got standard myeloablative HCT but didn't qualify for the non-TBI arm for various reasons.
Abdel-Azim and his team predicted these exact outcomes: around 75% EFS and 80% OS for NGS MRD-negative patients on non-TBI regimens. The research spanned 45 centers in North America from 2018 to 2025, showing broad applicability.
Who qualified for the treatment arm? Patients aged 1 to 31 in high-risk first or second complete remission (CR1 or CR2), where complete remission means no detectable leukemia. They could have had prior CAR T-cell therapy (a cutting-edge treatment using engineered immune cells) or blinatumomab (Blincyto, a targeted drug). But, babies under 1 year, those with a history of central nervous system relapse in CR2, T-cell ALL or mixed-phenotype leukemia, or active brain/extramedullary disease at transplant were shifted to the observational arm instead.
In the treatment group, the average age was 13.5 years (ranging from 2.3 to 30.5), with 51% boys. Donor matches varied: 37% had fully matched siblings, 35% had mismatched or haploidentical (partially matched) unrelated donors, 20% matched unrelated donors, and 8% used cord blood. Most (71%) received bone marrow grafts, 21% got peripheral blood stem cells, and 8% cord blood. At transplant, 49% were in CR1 and 51% in CR2.
“Surprisingly, the OS and EFS in our non-TBI arm for NGS MRD-negative B-ALL aligned perfectly with our expectations and rivaled results from MRD-negative patients on TBI in earlier trials,” Abdel-Azim summed up.
This finding sparks debate: while avoiding TBI reduces exposure to radiation that can cause long-term issues like secondary cancers or organ damage, is there a risk we're underestimating? For beginners, think of TBI as a whole-body bath in radiation—it's effective but harsh, like using a sledgehammer when a precise tool might suffice. By showing non-TBI works equally well for selected patients, the study challenges the status quo. But could this lead to broader adoption, or should we be cautious about applying it universally?
What do you think? Does this study convince you that non-TBI is the way forward for young leukemia patients, or are you worried about hidden downsides? Share your thoughts in the comments—let's discuss whether this could revolutionize cancer care!
Abdel-Azim's disclosures: Consultancy with Kite, Novartis, Vertex, and Johnson & Johnson; consultancy and research funding from Adaptive.
Reference
Abdel-Azim H, Quigg T, Kapoor N, et al. High event-free (EFS) and overall survival (OS) after non-total body irradiation (TBI) conditioning and allogeneic hematopoietic cell transplantation (HCT) in next-generation-sequencing minimal residual disease (NGS-MRD) negative B-acute lymphoblastic leukemia (B-ALL): Results from the EndRAD trial (PTCTC ONC1701). Blood. 2025;146(suppl 1):163. doi:10.1182/blood-2025-163
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