Reduced-intensity, conditioning, allogeneic stem cell transplantation (HSCT) significantly improved event-free survival (EFS) compared with continuous treatment with the DNA-methyltransferase inhibitor 5-azacitidine (5-aza) in elderly patients with myelodysplastic syndromes (MDS), according to the results of the VidazaAllo study published in the Journal of Clinical Oncology.

HSCT is a potentially curative treatment option for patients with MDS. However, it is frequently associated with treatment-related morbidity and mortality, especially in elderly patients, according to the study authors.

In the prospective, multicenter, open-label phase 2 study ( Identifier: NCT01404741), investigators compared 5-aza induction followed by HSCT according to donor availability with continuous 5-aza treatment in elderly patients (age range, 55-70 y) with MDS.

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A total of 162 patients received 5-aza induction therapy. During the 5-aza induction phase, 26 patients experienced disease progression, 12 patients died, and 16 patients were ineligible for HSCT for other reasons. According to donor availability, treatment was administered to the remaining 108 patients; 81 patients received allogeneic HSCT, and 27 patients received continuous 5-aza treatment.

After the patients were assigned to HSCT or continuous 5-aza treatment, there was no treatment-related mortality (TRM) reported in the 5-aza arm. However, at 1 year, the cumulative incidence of TRM following HSCT was 19%. The 3-year EFS was significantly higher after HSCT among the patients who underwent 5-aza induction (34%; 95% CI, 22-47) compared with those who received continuous 5-aza therapy (0%; P <.0001).

The 3-year overall survival (OS) after 5-aza pretreatment and HSCT was 50% (95% CI, 39-61) compared with 32% (95% CI, 14-52) after continuous 5-aza treatment (P =.12). Even though a significant improvement in EFS was observed among the patients who received HSCT compared with those who continued 5-aza therapy, the study did not meet its primary endpoint of a significantly improved 3-year OS.

In the continuous 5-aza arm, 14 of 27 patients had disease progression and underwent salvage HSCT with an alternative human leukocyte antigen (HLA)-mismatched donor.  At the last follow-up, 43% of these patients were surviving.

“The study confirmed that elderly patients up to age 70 years with higher-risk MDS and sufficient organ function do benefit from HSCT in comparison with 5-aza treatment,” the authors reported. “The high dropout rate of patients during the induction phase with 5-aza suggests, however, that timing of HSCT is essential and probably should be done as soon as a compatible donor is available without further delay.”

Disclosure: This research was supported by Celgene, Germany. Some study authors declared affiliations with biotech, pharmaceutical, and/or device companies. Please see the original reference for a full list of disclosures.


Kröger N, Sockel K, Wolschke C, et al. Comparison between 5-azacytidine treatment and allogeneic stem-cell transplantation in elderly patients with advanced MDS according to donor availability (VidazaAllo Study). J Clin Oncol. Published online July 20, 2021. doi:10.1200/JCO.20.02724