# Real-world safety and effectiveness of alemtuzumab as a conditioning regimen for hematopoietic stem cell transplantation

## TL;DR

This study evaluates the safety and effectiveness of alemtuzumab as a conditioning treatment before stem cell transplants in Japanese patients.

## Contribution

The study provides real-world evidence of alemtuzumab's safety and effectiveness in clinical practice in Japan.

## Key findings

- Alemtuzumab showed a manageable safety profile with a 64.4% incidence of adverse drug reactions.
- Engraftment was achieved in 94.8% of patients at a median of 16 days after HSCT.
- Predefined success criteria were met in 87.9% of patients.

## Abstract

Alemtuzumab, a humanized monoclonal antibody directed against CD52, is indicated for administration prior to allogeneic hematopoietic stem cell transplantation (HSCT) in Japan. This post-marketing surveillance study was conducted as part of a risk management plan to confirm the safety and effectiveness of alemtuzumab in clinical practice, as mandated by the Japanese health authorities. Fifty-nine patients aged 0 to 69 years received alemtuzumab prior to HSCT for hematologic malignancies (n = 22), aplastic anemia (n = 7), or other diseases (n = 30). The number of mismatched human leukocyte antigens between donor and recipient was ≥ 2 in 39 patients (66.1%), 1 in seven patients (11.9%) and 0 in 11 patients (18.6%). Overall, 38 of 59 patients (64.4%) developed an adverse drug reaction (ADR), most commonly fever associated with infusion reactions (n = 22); 24 patients (40.7%) had a serious ADR (most commonly cytomegalovirus-related events [n = 7]), and 16 had a grade ≥ 3 ADR (mainly febrile neutropenia [n = 3]). Engraftment was achieved in 55 of 58 patients (94.8%) at a median of 16 days after HSCT, and predefined success (engraftment without grade ≥ 3 graft-versus-host disease in hematologic malignancies or grade ≥ 2 in other diseases) was met in 51 of 58 patients (87.9%). These results support the manageable safety profile and effectiveness of alemtuzumab as preconditioning for HSCT in Japanese patients.

The online version contains supplementary material available at 10.1007/s12185-025-04033-w.