ASAP: Transplantation as soon as possible

The selection of patients for allo-HSCT and the best approach to bridging patients to transplantation is continuously discussed by experts. the first results of the ASAP study (ASAP standing for “as soon as possible”), published in 2024, have already attracted considerable attention. ASAP questions existing treatment standards for AML and was the first randomized controlled trial to compare remission induction with salvage chemotherapy prior to allo-HSCT – which represents the current standard of care (SOC) – against an option approach of immediate transplantation after intensified conditioning combined with non-intensive disease control strategies such as less aggressive chemotherapy or simple monitoring of leukemic proliferation. these two groups are referred to as the SOC arm and the alternative treatment arm, respectively.

the now published long-term analysis supports the initial results of the ASAP trial. The findings suggest that a transplantation as soon as possible yields comparable treatment outcomes as remission induction – with shorter hospital stays and reduced exposure to chemotherapy.

The results question the international standard of leukemia treatment. We no longer need to give all patients a very aggressive chemotherapy to reduce the tumor burden ahead of transplantation when regimens with good anti-leukemic activity are used for conditioning on the days prior to stem cell transplantation.

Prof. Dr. Johannes Schetelig, coauthor of the study

The results were based on a median follow-up of 61 months in the patient cohort: The induction of remission in the SOC arm (5-year OS: 47.5%) compared to immediate transplantation in the alternative treatment arm (5-year OS: 46.1%) showed no overall survival (OS) advantage in AML patients, which were poorly responsive to initial treatment or with untreated relapse. Since non-inferiority could not be demonstrated formally,immediate transplantation will not replace the common SOC but can be considered more often today. One argument in favor of proceeding directly to transplantation without remission induction is that patients who received intensive salvage chemotherapy in the SOC arm spent one month longer in hospital and experienced more adverse events.

Age and AML genetics are the most crucial risk factors influencing survival

The long-term follow-up of ASAP additionally analyzed treatment success according to risk classification and genetic subgroups. Both age and AML genetics were identified as the most important baseline risk factors influencing survival. AML genetics were classified according to the ELN 2022 criteria.