# Safety and Efficacy of High-Dose Chemotherapy with TreoMel 200 vs. TreoMel 140 in Acute Myeloid Leukemia Patients Undergoing Autologous Stem Cell Transplantation

## TL;DR

This study compares two doses of a chemotherapy regimen in AML patients undergoing stem cell transplants and finds no significant differences in outcomes or safety.

## Contribution

The study evaluates the safety and efficacy of increased melphalan doses in TreoMel-based conditioning regimens for AML patients.

## Key findings

- Higher melphalan doses (200 mg/m2) in TreoMel regimens are well tolerated with no significant increase in mortality or adverse events.
- No significant differences in relapse rates, progression-free survival, or overall survival were observed between the two dose groups.
- The study's small cohort size and short follow-up may have limited the ability to detect meaningful differences in outcomes.

## Abstract

Treosulfan and melphalan (TreoMel)-based high-dose chemotherapy (HDCT) has been successfully used as a conditioning regimen in acute myeloid leukemia (AML) patients undergoing autologous stem cell transplantation (ASCT). However, despite intensive first-line induction treatment and upfront consolidation with HDCT and ASCT, AML relapse rates are still high, and further efforts are needed to improve patient outcomes. In this study, we investigated how increased doses of melphalan impact the safety of HDCT with TreoMel and patient outcomes. A total of 51 AML patients were included in the analysis: 31 (60.8%) received standard-dose treosulfan combined with melphalan 140 mg/m2 (TreoMel 140) and 20 (39.2%) received melphalan 200 mg/m2 (TreoMel 200). There were no statistically significant differences in relapse (0.45 vs. 0.30, p = 0.381) and mortality rates (0.42 vs. 0.15, p = 0.064) between the melphalan 140 mg/m2 and 200 mg/m2 cohorts, nor for PFS (HR: 0.81, 95% CI: 0.29–2.28, p = 0.70) or OS (HR: 0.70, 95% CI: 0.19–2.57, p = 0.59) for the TreoMel 140 vs. TreoMel 200 cohorts. The side effect profile was comparable between both patient groups. Our results show that a higher melphalan dose is well tolerated. No significant differences for patient outcomes could be observed, possibly due to the relatively small patient cohort and short follow-up. Longer follow-up and prospective randomized studies would be required to confirm the safety profile and clinical benefit.

(1) Background: Treosulfan and melphalan (TreoMel)-based high-dose chemotherapy (HDCT) has shown promising safety and efficacy as a conditioning regimen for acute myeloid leukemia (AML) patients undergoing autologous stem cell transplantation (ASCT). However, despite intensive first-line induction treatment and upfront consolidation with HDCT and ASCT, AML relapse rates are still high, and further efforts are needed to improve patient outcomes. The aim of this study was to compare two melphalan dose schedules in regard to the safety of TreoMel HDCT and patient outcomes. (2) Methods: We retrospectively analyzed the safety and efficacy of two melphalan dose schedules combined with standard-dose treosulfan in AML patients undergoing HDCT and ASCT at the University Hospital of Bern, Switzerland, between August 2019 and August 2023. Patients received treosulfan 42 g/m2 combined with either melphalan 140 mg/m2 (TreoMel 140) or melphalan 200 mg/m2 (TreoMel 200). Co-primary endpoints were progression-free survival (PFS), overall survival (OS), as well as safety profile. (3) Results: We included a total of 51 AML patients: 31 (60.8%) received TreoMel 140 and 20 (39.2%) TreoMel 200. The patients’ basal characteristics were comparable between both cohorts. No significant differences in the duration of hospitalization or the adverse event profile were identified. There were no statistically significant differences in relapse (0.45 vs. 0.30, p = 0.381) and mortality rates (0.42 vs. 0.15, p = 0.064) between the melphalan 140 mg/m2 and 200 mg/m2 cohorts, nor for PFS (HR: 0.81, 95% CI: 0.29–2.28, p = 0.70) or OS (HR: 0.70, 95% CI: 0.19–2.57, p = 0.59) for the TreoMel 140 vs. TreoMel 200 cohort. (4) Conclusions: A higher dose of melphalan (TreoMel 200) was well tolerated overall. No statistically significant differences for patient outcomes could be observed, possibly due to the relatively small patient cohort and the short follow-up. A longer follow-up and prospective randomized studies would be required to confirm the safety profile and clinical benefit.