Beyond the Biopsy: A New Blood Test Is Redefining the Fight Against Relapsed AML

For a patient battling acute myeloid leukemia (AML), a relentless and aggressive cancer of the blood and bone marrow, the words allogeneic stem cell transplant (allo-SCT) carry an immense weight of hope. This procedure, which replaces a patient's diseased marrow with healthy, cancer-fighting stem cells from a donor, stands as one of our most powerful curative therapies. It offers the promise of a new beginning, a life free from leukemia. Yet, for all its power, the journey is fraught with uncertainty. The single greatest fear that looms over patients and their families in the months and years following a transplant is the specter of relapse.

Managing relapsed disease after allo-SCT is a formidable challenge. It means that despite the high-intensity chemotherapy, radiation, and the infusion of a brand-new immune system, some leukemia cells managed to survive the onslaught. These residual cells, a hidden enemy, can lie dormant before re-emerging, often with increased resistance to treatment. For decades, the central challenge in post-transplant care has been to detect measurable residual disease (MRD) early enough to act.

The traditional gold standard for MRD detection has been the bone marrow biopsy. This invasive procedure, while informative, has significant drawbacks. It is painful, carries a risk of complications, and can be particularly taxing for patients who are already frail from their treatment. Furthermore, because leukemia can sometimes return in patchy, localized areas within the marrow, a biopsy needle can simply miss the spot, leading to a false sense of security. We needed a better way—a method that was less invasive, more sensitive, and could provide a more complete, systemic picture of what was happening inside the patient's body.

Now, we believe we have found a powerful new tool that meets these criteria. At Hackensack University Medical Center, our research has focused on the promise of liquid biopsy, a revolutionary approach that hunts for cancer's molecular footprints in a simple blood sample. Our study, published in Transplantation and Cellular Therapy in August 2025, demonstrates that testing for tumor-associated circulating cell-free DNA (cfDNA) can serve as a remarkably accurate early warning system for relapse, potentially changing the way we treat patients with AML following allo-SCT.1

What is the science behind liquid biopsy?

Every cell in our body, including cancerous ones, sheds tiny fragments of its DNA into the bloodstream as it dies. This is what we call cfDNA. When these fragments originate from tumor cells, they carry the same genetic mutations that drive the cancer. By using highly sensitive next-generation sequencing (NGS) technology, we can detect these specific tumor mutations in a vial of blood, even when they are present at incredibly low levels.

The advantages of this approach are profound. A blood draw is minimally invasive and can be performed frequently without significant burden to the patient. This allows for dynamic, serial monitoring over time, creating a moving picture of the disease's status rather than a single, static snapshot. It offers a systemic view, capturing DNA shed from cancer cells anywhere in the body, overcoming the sampling limitations of a bone marrow biopsy.

Building on our previous work, which showed we could detect these signals as early as 28 days post-transplant, our new, larger study aimed to answer a critical question: Can the presence of cfDNA in the blood at a key post-transplant time point reliably predict a patient's long-term outcome?

What was the design of this retrospective study?

We conducted a retrospective analysis of 90 patients with AML who received their first allo-SCT for primary disease at our institution between January 2018 and December 2022. We focused our analysis on a crucial window: Day 150, plus or minus 50 days, which is approximately 3 to 7 months post-transplant. This time point is critical. It is late enough for the new donor immune system to have established itself and begun its work of eradicating any remaining leukemia—a process known as the graft-vs-leukemia (GvL) effect. At the same time, it is early enough that if residual disease is detected, we still have a window of opportunity to intervene before clinical relapse occurs.

For each patient, we analyzed peripheral blood samples using a comprehensive genomic sequencing panel that screens for mutations in over 300 genes associated with blood cancers. We defined a positive result as the detection of any known tumor-associated mutation, and a negative result as the absence of these mutations.

We then went a step further. Not all genetic mutations carry the same weight. The 2022 European LeukemiaNet (ELN) guidelines provide a framework for stratifying AML mutations into 3 risk categories: favorable, intermediate, and adverse. We used this classification system to see if the type of mutation detected post-transplant had an even greater impact on prognosis.

What did the results indicate about the prognostic value of cfDNA testing?

The data that emerged from our analysis were not just statistically significant; they were clinically profound. They confirmed our hypothesis in the clearest possible terms.

Patients who tested positive for any cfDNA at the Day 150 time point had dramatically worse outcomes compared with patients who tested negative. Their overall survival (OS) and relapse-free survival (RFS) outcomes were 5.4 times and 5.2 times higher in patients who tested negative compared with those who tested positive.

When we stratified these results by mutation risk, the signal became even stronger. The persistence of adverse-risk mutations—such as those in genes like TP53, ASXL1, or RUNX1—was a particularly ominous sign. Patients with these mutations faced a 11.2-fold increased risk of death and an 11.6-fold increased risk of relapse compared with their cfDNA-negative counterparts. Even the presence of intermediate-risk mutations was highly predictive, conferring a 5.5-fold risk of death and a 6.6-fold risk of relapse.

To put these numbers in human terms, our survival-curve analysis painted a stark picture. At the 3-year mark post-transplant, approximately 85% of patients who were cfDNA negative were still alive. In contrast, only 45%of those who were cfDNA positive had survived. For the group with persistent adverse-risk mutations, the outlook was even more dire: their probability of RFS decreased to just 25% one year after testing.

The data also highlighted the importance of clearing these mutations. Patients who started with adverse-risk mutations before their transplant but were cfDNA negative by Day 150 had significantly better outcomes than those whose adverse mutations persisted. This demonstrates that the goal of transplantation—to eradicate the leukemic clone—can be effectively tracked with this blood test. Any detectable mutation, regardless of its risk classification, was evidence of MRD that predicted relapse and represented an actionable finding.

What are the clinical implications of these findings for patients with AML?

These findings are more than just academic. They have direct implications for how we can and should care for our patients. The detection of cfDNA is not merely a prognostic marker; it is a call to action. Identifying a patient as cfDNA positive at 5 months post-transplant should trigger a fundamental shift in the way we approach their management. It tells us that the current strategy is insufficient and that the patient is on a trajectory toward relapse.

This early warning gives us a precious opportunity to intervene pre-emptively. Potential interventions could include carefully tapering immunosuppressive drugs to unleash a stronger GvL effect, administering an infusion of donor lymphocytes (DLI) to bolster the new immune system's attack on the cancer, or initiating targeted molecular therapies or other novel agents. By acting when the disease burden is still microscopic, we have a much greater chance of success than if we wait for a full clinical relapse.

Of course, the story is complex. We noted that many patients who successfully cleared their mutations had also experienced a degree of graft-vs-host disease (GvHD), a condition where the donor immune cells attack the recipient's body. This hints at the powerful double-edged sword of the GvL effect, but the relationship requires further study to be fully understood.

We must also be mindful of the challenges. One of the key diagnostic hurdles is distinguishing true leukemia-derived MRD from a phenomenon called clonal hematopoiesis of indeterminate potential (CHIP). CHIP involves the presence of age-related mutations in blood stem cells that are not necessarily cancerous but can be picked up by sensitive NGS tests. Disentangling these benign signals from the truly dangerous ones is a critical area of ongoing research.

What next steps are needed to integrate cfDNA testing into clinical practice?

Our study, while powerful, has its limitations. It was a retrospective analysis from a single center, and the patient population had varied conditioning regimens and donor types. The timing of the test was at the physician's discretion rather than part of a rigid protocol. Therefore, the next step is clear: we need larger, prospective, multicenter trials to validate these findings and establish standardized protocols for cfDNA monitoring.

The ultimate vision is to integrate serial cfDNA testing as the standard of care for all patients with AML post-transplant. Imagine a future where a patient's follow-up visit involves a simple, routine blood draw. Within days, their physician receives a report detailing their MRD status with exquisite sensitivity. If the test is negative, it provides profound reassurance. If it becomes positive, it triggers an immediate, pre-planned therapeutic response designed to eliminate the residual disease before it can take hold.

This is the promise of personalized, proactive medicine. It is about shifting the paradigm from reacting to a relapse to preventing one. For the thousands of patients who place their hope in a stem cell transplant, this technology represents more than just a scientific advancement. It represents a tangible path toward greater certainty, better outcomes, and the ultimate goal we all share: a lasting cure.