# An approach to autologous stem cell mobilization: trying to define good mobilizers

## TL;DR

This study identifies factors that predict successful stem cell mobilization, enabling earlier harvesting and reducing treatment duration.

## Contribution

The study introduces a novel definition and identification of 'good mobilizers' based on CD34+ cell counts on Day +4.

## Key findings

- 62% of patients with ≥40 CD34+ cells/μL achieved sufficient cell collection in a single apheresis.
- A cutoff of 102 CD34+ cells/μL on Day +4 showed a 94% success rate.
- Most good mobilizers had no or only one risk factor for poor mobilization.

## Abstract

Stem cell mobilization is a well-known procedure to harvest hematopoietic stem cells for autologous stem cell transplantation in certain hematologic diseases. Numerous studies have been conducted to identify risk factors for poor mobilization but there are no studies that identify good mobilizers. In our hospital, we decided to explore good mobilizers, defining them as those with ≥40 CD34+ cells/μL on Day +4 in order to start early apheresis.

A descriptive retrospective study was performed at Hospital Universitari Son Espases. A total of 198 patients mobilized with doses of around 10 µg/kg of granulocyte colony-stimulating factor (G-CSF) every 12 h were analyzed for autologous collection between January 2015 and September 2022. Fifty patients who had ≥40 CD34+ cells/μL on Day +4 started early apheresis; the rest continued mobilization as planned. Success was defined as obtaining over 2.5 × 106 CD34+ cells/kg in a single apheresis.

The necessary number of CD34+ cells/kg to perform an autologous stem cell transplantation was reached in a single apheresis session in 62 % of patients with ≥40 CD34+ cells/μL in peripheral blood. A cutoff of 102 CD34+ cells/μL on Day +4 was shown to have the best success rate (94 %). In an analysis of success, age, previously failed mobilization and having one or more adverse factors for bad mobilization were statistically significant.

Patients considered as good mobilizers were matched with our factors of poor mobilization, revealing that most patients (79 %) had none or only one risk factor for poor mobilization. Apheresis on Day +4 in good mobilizers was shown to be an effective alternative to reduce mobilization duration and decrease the amount of granulocyte-colony stimulating factor administered.