A multicenter report on the safety and efficacy of plerixafor based stem cell mobilization in children with malignant disorders

Predictive factors for engraftment kinetics of autologous hematopoietic stem cells in children

BACKGROUND

Engraftment after hematopoietic stem cell transplantation is the recovery rate of neutrophils and platelets. This study aimed to test the impact of the patient's general characteristics, pre-transplantation factors, and quality parameters of hematopietic stem cell products on hematopietic recovery and to define predictive factors for engraftment in children.

METHODS

This retrospective study included 52 patients aged from 1 to 18 years old treated with autologous transplantation at the Mother and Child Health Care Institute of Serbia "Dr. Vukan Čupić" in Belgrade, from January 2013 until December 2018. Data were collected from medical records and apheresis procedure protocols. SPSS 20.0 software package was used for statistical data processing.

RESULTS

The median neutrophil engraftment was 18.0 (16.0-22.5) days, while the median platelet engraftment was 11.0 (10.0-18.0) days. Statistically significant correlations were found between neutrophil engraftment and patient's age (p-value = 0.050), body weight (p-value = 0.021), diagnosis (p-value = 0.023), source of stem cells (p-value = 0.001), and the number of CFU-GM/kg (p-value = 0.018). A statistically significant correlation was found between platelet engraftment and the time from diagnosis to the transplantation (p-value = 0.043), source of stem cells (p-value = 0.009), and the number of CD34+ cells/kg (p-value = 0.014).

CONCLUSIONS

Predictive factors for hematopoietic recovery in this study were the patient's age, body weight, diagnosis, time from diagnosis to hematopoietic stem cell transplantation, source of hematopietic stem cells, the number of CD34+ cells/kg, and the number of CFU-GM/kg.

Single-center results reporting improved hematopoietic stem cell mobilization success in pediatric and young adult patients with solid tumors and lymphoma

BACKGROUND

High-dose chemotherapy with autologous hematopoietic stem cell transplantation (auto-HSCT) is an established treatment for pediatric and young adult patients with solid tumors and lymphomas. Plerixafor is a CXC chemokine receptor type 4 (CXCR4) antagonist that can be used with granulocyte colony stimulating factor (G-CSF) to amplify the mobilization of hematopoietic stem cells (HSCs).

METHODS

We performed a retrospective analysis of 167 pediatric solid tumor and lymphoma patients from January 2010 to July 2020 in whom HSCs were mobilized using G-CSF alone or with plerixafor.

RESULTS

Thirteen heavily pretreated patients (33.3%) required twice-daily dosing of G-CSF compared to five patients (3.9%) in the not heavily pretreated group (p = .0005). Fourteen heavily pretreated patients (35.9%) required plerixafor compared to four patients (3.1%) in the comparison cohort (p = .0002). The number of mobilization days was similar between both cohorts, with 5 days (range 3-11 days) in the heavily pretreated group and 5 days (range 3-13 days) in the not heavily pretreated group (p = .55). The number of harvest days was 2 days (range 1-5 days) in the heavily pretreated group and 1 day (range 1-4 days) in the not heavily pretreated group (p = .0025). The final cluster of differentiation (CD)34⁺ /kilogram (kg) count was 9.52 × 10⁶ /kg among heavily pretreated patients compared to 34.99 × 10⁶ /kg CD34⁺ cells in the comparison group (p < .0001). Three heavily pretreated patients (7.7%) failed HSC mobilization.

CONCLUSIONS

Patients at the highest risk for poor HSC mobilization can be successfully treated with more frequent G-CSF dosing or G-CSF with plerixafor in a large majority of cases.

Use of Plerixafor for Stem Cell Mobilization in the Setting of Autologous and Allogeneic Stem Cell Transplantations: An Update

Mobilization failure is an important issue in stem cell transplantations. Stem cells are yielded from the peripheral blood via apheresis. Granulocyte colony-stimulating factor (G-CSF) is the most commonly used mobilization agent among patients and donors. G-CSF is administered subcutaneously for multiple days. However, patients with mobilization failure cannot receive autologous stem cell transplantation and, therefore, cannot be treated adequately. The incidence rate of mobilization failure among patients is about 6–23%. Plerixafor is a molecule that inhibits the binding of chemokine receptor-4 with stromal-cell-derived factor-1, thereby resulting in the release of CD34+ cells in the peripheral blood. Currently, plerixafor is used in patients with mobilization failure with G-CSF and is administered subcutaneously. Several studies conducted on different clinical settings have shown that plerixafor is effective and well tolerated by patients. However, more studies should be conducted to explore the optimal approach for plerixafor in patients with mobilization failure. The incidence of mobilization failure among donors is lower. However, plerixafor is not approved among donors with mobilization failure. Moreover, several clinical studies in donors have shown a beneficial effect of plerixafor. In addition, the adverse events of plerixafor are mild and transient, which can overcome the adverse events due to G-CSF. This review assessed the current role and effects of plerixafor in stem cell mobilization for autologous and allogeneic stem cell transplantations.