Frontline Allogeneic Transplantation Outperforms Pretransplant IPSS-M Downstaging in Myelodysplastic Neoplasms

Highlights

In this retrospective single-center analysis of 128 adults with myelodysplastic neoplasms undergoing allogeneic hematopoietic cell transplantation, pretransplant therapy did not translate into better post-transplant outcomes.

Although IPSS-M improved before transplantation in a subset of patients, molecular or composite-risk “downstaging” was modest and showed no clear survival advantage.

Frontline transplantation was associated with longer overall survival, relapse-free survival, and graft-versus-host disease/relapse-free survival in the primary analysis, while pretreatment was linked to significantly higher non-relapse mortality.

The findings support early donor identification and risk-guided transplant timing rather than routine use of cytoreductive therapy solely to improve IPSS-M before transplantation.

Background

Myelodysplastic syndromes, now increasingly termed myelodysplastic neoplasms (MDS) in modern classifications, represent a biologically heterogeneous group of clonal myeloid disorders characterized by ineffective hematopoiesis, cytopenias, genetic instability, and risk of progression to acute myeloid leukemia. For eligible patients, allogeneic hematopoietic cell transplantation remains the only established curative therapy. The central practical question is not whether transplantation can cure some patients, but when it should be delivered and whether disease-directed treatment before transplantation improves outcomes.

For years, clinicians have used marrow blast percentage, cytogenetics, response depth, transfusion burden, and comorbidity to decide whether to proceed directly to transplant or to give bridging therapy first. Hypomethylating agents, induction-type chemotherapy, and other cytoreductive strategies are often used with the intention of lowering disease burden, reducing leukemic progression risk, and improving transplant readiness. Yet the evidence base for these strategies has remained inconsistent. The biologic rationale is intuitive, but retrospective studies have repeatedly struggled to show a durable survival benefit from pretransplant cytoreduction, especially when therapy delays transplantation or adds toxicity.

The introduction of the Molecular International Prognostic Scoring System (IPSS-M) has sharpened this debate. Unlike older scoring systems, IPSS-M incorporates molecular abnormalities alongside cytopenias, blast count, and cytogenetics, offering more refined risk estimation. This raises a new clinical question: if a patient’s IPSS-M category improves after therapy, does that “downstaging” meaningfully change transplant prognosis? The study by Richardson and colleagues directly addresses this issue.

Study Design and Methods

Design and population

This was a retrospective analysis of 128 consecutive adult patients with MDS who underwent allogeneic stem cell transplantation. Patients were divided into two groups: those who received frontline transplantation without prior cytoreductive treatment (n = 87) and those who were pretreated before transplant (n = 41).

Exposure of interest

The key comparison was immediate or frontline transplantation versus transplantation after disease-directed pretreatment. The abstract does not specify all pretreatment regimens in detail, but in clinical practice such approaches generally include hypomethylating agents and, less commonly, intensive chemotherapy or other cytoreductive strategies.

Risk assessment

IPSS-M was calculated at diagnosis and again immediately before transplantation using cytogenetic and next-generation sequencing data. This is an important design feature because it moves beyond conventional morphologic response and attempts to capture changes in molecularly informed disease risk over time.

Endpoints

The principal outcomes included overall survival (OS), relapse-free survival (RFS), and graft-versus-host disease/relapse-free survival (GRFS). The investigators also assessed non-relapse mortality (NRM), a particularly relevant endpoint because pretransplant therapy may affect fitness, infectious complications, organ reserve, and transplant-related toxicity even if it lowers disease burden.

Baseline disease burden

Median bone marrow blast percentage at diagnosis was similar between groups, 12% in the frontline transplant cohort and 10% in the pretreated cohort. That observation is helpful because it suggests the study was not simply comparing patients with widely divergent initial blast burdens, although important unmeasured differences in biology and clinical selection may still have existed.

Key Results

IPSS-M changes before transplantation

The central biologic observation is that IPSS-M changed over time in both groups, but improvements were modest and not confined to patients receiving pretransplant therapy. Among frontline transplant patients, IPSS-M improved in 26%, was unchanged in 41%, and worsened in 30%. In the pretreated group, IPSS-M improved in 34%, remained unchanged in 34%, and worsened in 32%.

These numbers deserve close attention. First, the improvement rate with pretreatment was only modestly higher than with frontline transplantation. Second, roughly one-third of pretreated patients had worsening IPSS-M despite therapy. Third, changes in IPSS-M were not unidirectional; dynamic molecular risk remained unstable. Taken together, this suggests that attempts to optimize transplant candidacy by “downstaging” IPSS-M may be less reliable than clinicians hope.

Overall survival

After a median follow-up of 17.3 months, overall survival favored frontline transplantation. Median OS was 112.6 months in the frontline group versus 14.0 months in the pretreated group, with p = 0.03. On first reading, this is a striking difference and appears to strongly favor proceeding directly to transplant.

However, the investigators also performed a landmark analysis beginning at the time of transplantation, and in that analysis the OS difference was no longer statistically significant. This is a critical methodological point. In retrospective transplant studies, patients who receive bridging therapy must survive long enough to actually undergo transplantation, and the pretransplant interval can distort apparent outcomes in either direction. A landmark analysis partially addresses this bias. The loss of statistical significance in the landmark analysis suggests that at least part of the apparent OS advantage in the primary comparison may reflect timing-related biases or differences in events occurring before transplant rather than a pure post-transplant effect.

Relapse-free survival

Relapse-free survival remained better with frontline transplantation: median RFS was 61.0 months versus 8.9 months, with p = 0.007. This finding is clinically meaningful because it indicates that pretreatment did not improve disease control after transplantation, despite some reduction in IPSS-M category in selected patients. If pretransplant cytoreduction were achieving its intended goal, one would expect at least a signal toward lower relapse or longer disease-free remission, but that was not observed.

GRFS

GRFS, a composite endpoint integrating freedom from severe graft-versus-host disease, relapse, and death, was also superior in the frontline cohort: median GRFS 13.3 months versus 5.3 months, p = 0.004. This is especially relevant for transplant physicians because GRFS reflects not just survival but survival without major transplant-related morbidity. The poorer GRFS in the pretreated cohort reinforces the idea that pretreatment may add clinical burden without delivering sufficient anti-disease benefit.

Non-relapse mortality

One of the most important findings was significantly higher non-relapse mortality in pretreated patients (p = 0.018). Although the abstract does not provide absolute NRM percentages, the statistical signal is clear. This shifts the interpretation of the study from simple therapeutic inefficacy to possible net harm in some patients. Even if pretreatment modestly lowers blast count or improves composite risk classification, that advantage may be offset by treatment-related complications, cumulative immunosuppression, infectious risk, organ toxicity, delayed transplant, or poorer functional reserve by the time conditioning begins.

Clinical Interpretation

The practical message is straightforward: improving IPSS-M before allogeneic transplantation is not the same as improving transplant prognosis. This distinction matters. IPSS-M is a powerful prognostic tool, but using it as a treatment response target before transplant may not be appropriate. Prognostic scores help estimate baseline and evolving risk; they are not automatically validated as surrogate endpoints for survival benefit after a definitive intervention such as transplantation.

The data suggest that disease-directed therapy before transplant should not be routine if the primary goal is simply to achieve a lower IPSS-M category. For transplant-eligible patients with a donor option, earlier transplantation may preserve clinical fitness and avoid excess non-relapse mortality. This aligns with a long-standing principle in MDS management: once transplantation is indicated, delaying curative therapy in pursuit of an imperfect remission can be counterproductive.

These findings are especially relevant in the era of broad molecular testing. As next-generation sequencing becomes standard, clinicians may be tempted to monitor serial mutational profiles and defer transplantation until molecular risk appears to improve. This study argues for caution. Clonal dynamics in MDS are complex, and some adverse molecular features may persist even when marrow morphology looks better. Conversely, transient improvement in a risk score may not capture the patient-level consequences of additional therapy.

Strengths of the Study

The study has several notable strengths. It addresses a genuinely contemporary clinical question by using IPSS-M rather than relying only on older prognostic models. It includes consecutive adult transplant recipients, which reduces some forms of case selection within the transplant population. It also evaluates outcomes that matter directly to patients and clinicians, including OS, RFS, GRFS, and NRM.

Another strength is the use of risk assessment at two time points, diagnosis and immediately before transplantation, integrating cytogenetics and molecular data. This design allows the investigators to examine whether dynamic changes in molecularly informed risk correspond to transplant outcomes, which is exactly the question many clinicians face in practice.

Limitations and Sources of Bias

As with any retrospective transplant study, confounding by indication is a major limitation. Patients who were pretreated were likely selected for reasons not fully captured in the abstract: physician concern about disease biology, donor availability, performance status, comorbidity, marrow kinetics, infection history, or social timing factors. Those variables can influence both the decision to bridge and the eventual transplant outcome.

The sample size was modest, particularly in the pretreated arm, which limits subgroup analysis and precision. The follow-up duration, with a median of 17.3 months, is also relatively short for a disease in which late relapse and chronic graft-versus-host disease can shape long-term outcomes. The dramatic difference in median OS should therefore be interpreted with some caution, especially given the landmark analysis finding.

Another limitation is the lack of granular data in the abstract on pretreatment regimen type, treatment response depth, conditioning intensity, donor source, measurable residual disease, comorbidity burden, and causes of non-relapse mortality. These factors could help explain why the pretreated group fared worse and whether any specific subgroup might still benefit from bridging therapy.

Finally, IPSS-M itself, while highly informative, was developed as a prognostic system and not specifically as a dynamic on-treatment endpoint for transplant decision-making. A change in score may reflect biologic evolution, therapy effect, sampling variability, or clonal selection, but not all such changes are equally meaningful with respect to post-transplant cure.

How This Fits With Existing Evidence

Current MDS management guidelines generally support allogeneic transplantation for eligible patients with higher-risk disease, with timing individualized by disease risk, age, comorbidities, and donor access. They do not uniformly require pretransplant cytoreduction for all patients. In practice, many centers reserve bridging therapy for patients with excess blasts, rapidly progressive disease, or unavoidable delays in donor procurement or transplant logistics.

The present study is consistent with the broader literature suggesting that pretransplant therapy in MDS has not consistently improved survival after allogeneic transplantation. Hypomethylating agents can be useful as a bridge when transplantation cannot be performed promptly, and they may stabilize disease in some patients. But stabilization is not equivalent to superior post-transplant outcome. This study strengthens the argument that donor search and transplant planning should begin early, especially in patients with higher molecular risk.

It also underscores an important conceptual issue in modern hematology: increasingly sophisticated prognostic tools should inform timing and counseling, but not necessarily become therapeutic endpoints in their own right without validation. IPSS-M may be excellent for identifying who needs transplant, but less useful as a pretransplant “score to normalize.”

Implications for Practice

When to consider frontline transplantation

For transplant-eligible adults with MDS, especially those with higher-risk molecular features, these results favor early referral and rapid donor identification. If a suitable donor is available and the patient is medically ready, proceeding to transplant without attempting score-based downstaging appears reasonable and may be preferable.

When bridging therapy may still be appropriate

This study should not be interpreted as proving that pretreatment is never useful. Bridging therapy may still be appropriate when transplantation is delayed, when blast burden is high enough to threaten imminent progression, or when symptomatic disease control is urgently needed. However, the rationale in those settings is disease containment or logistical necessity, not confidence that improved IPSS-M will produce better transplant outcomes.

What clinicians should discuss with patients

Patients often assume that more treatment before transplant will improve the chance of success. These data offer a more nuanced message: additional therapy can sometimes reduce visible disease burden, but it may also increase toxicity, delay curative treatment, and fail to improve long-term outcomes. Shared decision-making should therefore include discussion of the tradeoff between transient cytoreduction and the risks of postponing transplantation.

Future Research Directions

Prospective studies are needed to determine whether specific biologic subgroups benefit from bridging therapy before transplantation. Future trials should integrate measurable residual disease, serial molecular profiling, regimen-specific analyses, and patient fitness metrics. It will also be important to distinguish morphologic response from clonal clearance and to identify which mutations retain prognostic significance after transplantation.

Another useful direction would be to compare immediate transplant versus protocolized short-course bridging in patients with defined donor-search timelines. Such studies could clarify whether there is a narrow subset in whom disease debulking adds value without materially increasing non-relapse mortality.

Funding and Trial Registration

The abstract provided does not report specific funding information or a ClinicalTrials.gov registration number. The study was retrospective rather than a registered interventional trial.

Conclusion

Richardson and colleagues provide timely evidence that pretransplant IPSS-M downstaging should not be assumed to improve outcomes in MDS. In this cohort, cytoreductive pretreatment produced only modest changes in IPSS-M, did not improve post-transplant disease control, and was associated with higher non-relapse mortality. While primary analyses favored frontline transplantation across several endpoints, the landmark overall survival analysis appropriately tempers causal interpretation. Even so, the overall message is clinically persuasive: once a patient is considered a suitable transplant candidate, efforts should focus on timely donor identification and efficient transition to allogeneic transplantation rather than on pursuing molecular-risk downstaging as a standalone pretransplant objective.

References

1. Richardson T, Schütte D, Gödel P, von dem Bongart C, Burkhard-Meier C, Lorsy E, Kreuzer K, Frenzel L, Hallek M, Holtick U, Scheid C. IPSS-M downstaging before transplantation does not improve the prognosis of patients with myelodysplastic neoplasms. Bone Marrow Transplantation. 2026;61(5):584-590. PMID: 41917167.

2. Bernard E, Tuechler H, Greenberg PL, Hasserjian RP, Ossa JEA, Nannya Y, et al. Molecular International Prognostic Scoring System for myelodysplastic syndromes. NEJM Evidence. 2022;1(7). This study established IPSS-M and its integration of molecular genetics into MDS risk stratification.

3. de Witte T, Bowen D, Robin M, Malcovati L, Niederwieser D, Yakoub-Agha I, et al. Allogeneic hematopoietic stem cell transplantation for MDS and CMML: recommendations from an international expert panel. Blood. 2017;129(13):1753-1762.

4. National Comprehensive Cancer Network. NCCN Clinical Practice Guidelines in Oncology: Myelodysplastic Syndromes. Current publicly available guideline versions support risk-adapted transplant referral and individualized pretransplant therapy decisions.