Allo-HCT Achieves Durable Remission in Complex Multiple Myeloma Case

There is renewed discussion around the role of allogeneic hematopoietic cell transplantation (allo-HCT) in the treatment of complex hematologic cancers following the publication of a new case report, even as newer immunotherapies such as chimeric antigen receptor (CAR) T-cell therapy continue to reshape the treatment landscape.¹

The report describes a patient with highly refractory multiple myeloma (MM) who developed therapy-related myelodysplastic syndrome and acute myeloid leukemia (MDS/AML), rare but increasingly recognized and often fatal complications of long-term cancer treatment, including chemotherapy, radiotherapy, and immunotherapy.^2,3 Following allo-HCT, the patient achieved durable remission of both malignancies and remained disease free for approximately 3 years following transplant, without the need for maintenance therapy.

This case, published in eJHaem, suggests that allo-HCT may still have a meaningful role in carefully selected patients, particularly those with complex or overlapping hematologic malignancies. The authors caution that the findings are based on a single patient and may not be broadly generalizable. Nonetheless, the report highlights the need to reconsider existing treatment paradigms as new therapies emerge for MM.

Although increasingly treatable due to advances in targeted therapies and immunotherapy, MM remains largely incurable. Over time, patients often receive multiple lines of therapy, including proteasome inhibitors, immunomodulatory drugs, monoclonal antibodies, and autologous stem cell transplant. These treatments have extended survival but have also introduced new long-term risks.

One such risk is the development of therapy-related myeloid neoplasms, including MDS and AML. These conditions arise because of prior chemotherapy or radiation exposure and are associated with poor prognosis and limited treatment options. Allogeneic transplantation is widely considered the only potentially curative approach for these secondary malignancies.

The patient described in the report had an aggressive and atypical presentation of MM, initially characterized by extramedullary disease and high-risk features, including 17p deletion. Over the course of several years, she underwent multiple intensive treatment regimens, including 2 autologous stem cell transplants and combinations of novel agents. Despite these efforts, the disease repeatedly relapsed and progressed.

Approximately 5 years after her initial diagnosis, the patient developed progressive cytopenias, prompting further evaluation. Bone marrow testing revealed 17% blasts, confirming a diagnosis of therapy-related MDS/AML. Genetic analysis identified a distinct myeloid clone, separate from the original myeloma, reinforcing the diagnosis of a secondary malignancy rather than disease evolution.

Given the aggressive nature of both conditions, clinicians pursued allo-HCT, using umbilical cord blood as the donor source.

“Notably, the choice of umbilical cord blood as the graft source may also have contributed to the favorable outcome in this complex and high-risk clinical scenario,” noted the researchers. “Emerging registry data from the [Center for International Blood and Marrow Transplant Research] suggest that [umbilical cord blood transplant] may provide potent graft-vs-leukemia effects in patients with active or high-risk acute myeloid leukemia, including those who are not in remission at the time of transplantation.”

Prior to transplant, the patient received cytoreductive therapy to reduce disease burden. Conditioning therapy included a combination of chemotherapy and low-dose total body irradiation to prepare the bone marrow for engraftment.

The transplant was successful, with neutrophil and platelet recovery occurring within several weeks. Early posttransplant assessments confirmed complete remission of MDS/AML and MM. Although the patient experienced mild acute graft-vs-host disease affecting the liver, this complication was effectively managed with corticosteroid therapy and resolved without progression to chronic disease.

Approximately 3 years after transplantation, the patient remained in complete remission from MDS/AML and in stringent complete response for MM, with sustained minimal residual disease negativity. She required no additional maintenance therapy during this period.

The case is particularly notable given the current treatment landscape. CAR T-cell therapies and other advanced immunotherapies have demonstrated impressive response rates in relapsed or refractory MM, but they are not yet considered curative, as most patients eventually experience relapse.

In contrast, allo-HCT offers the potential for long-term disease control through a graft-vs-tumor effect, in which donor immune cells help eliminate residual cancer cells. However, due to its associated risks, including treatment-related mortality and graft-vs-host disease, its use in MM has declined in recent years.

References

1. Kumamoto T, Yoshihara K, Samori M, et al. Durable remission of highly refractory multiple myeloma and therapy-related MDS/AML after allogeneic hematopoietic cell transplantation: reconsidering its role in the CAR-T era. eJHaem. Published online April 10, 2026. doi:10.1002/jha2.70282
2. Venugopal S, DeZerrn AE. Therapy-related myelodysplastic syndromes and acute myeloid leukemia. Semin Hematol. 2024;61(6):379-384. doi:10.1053/j.seminhematol.2024.09.004
3. Morrton LM, Curtis RE, Linet MS, et al. Trends in risk for therapy-related myelodysplastic syndrome/acute myeloid leukemia after initial chemo/immunotherapy for common and rare lymphoid neoplasms, 2000-2018. EClinicalMedicine. 2023;61:102060. doi:10.1016/j.eclinm.2023.102060