G-CSF Only Versus Chemotherapy and G-CSF Peripheral Blood Stem Cell Mobilization for Autologous Hematopoietic Stem Cell Transplant-Assessing a Change in Regime due to the COVID-19 Pandemic.

Autologous stem cell transplant (ASCT) requires the collection of hematopoietic progenitor cells, commonly by apheresis (HPC-A). These CD34+ cells can be mobilized using Granulocyte Colony Stimulating Factor (G-CSF) only or chemomobilization plus G-CSF. Both methods may additionally include Plerixafor. The emergence of COVID-19 led to recommendations for preferential G-CSF only mobilization. To assess the impact of this recommendation on HPC-A harvesting, we analyzed data from the NHS Blood and Transplant Stem Cell Collection Registry for 1342 patients undergoing 2431 HPC-A procedures between 01/01/2019 and 31/12/2021. We compared G-CSF only, cyclophosphamide plus G-CSF (Cyclo-G) and G-CSF plus alternative chemotherapy (Chemo+G) mobilization. The outcomes collected were pre-apheresis CD34+ count, CD34+ yield per procedure, total CD34+ yield, number of apheresis procedures required to achieve the CD34+ target, mobilization failure, and Plerixafor use (+P). In multiple myeloma (MM), Cyclo-G (+/-P) mobilization produced significantly higher CD34+ yields than G-CSF only (7.44 vs. 4.75 × 106/kg; p < 0.0001). In Hodgkin lymphoma (HL) there was no statistically significant difference between regimes (CD34+ yield 4.53 × 106/kg with G-CSF only (+/-P), 5.52 × 106/kg with Cyclo-G (+/-P), 4.32 × 106/kg with Chemo+G (+/-P)). In Non-Hodgkin lymphoma (NHL), Chemo+G (+/-P) was the most successful regime (5.98 × 106/kg vs. 3.7 × 106/kg with G-CSF only (+/-P) vs. 3.69 × 106/kg with Cyclo-G (+/-P); p < 0.00001). On demand Plerixafor use resulted in > 95% successful mobilization in MM and NHL. CD34+ yields are higher using Cyclo-G and Chemo+G in NHL. In MM, G-CSF only resulted in yields sufficient for at least one transplant. In HL, our data show no evidence to support the use of Cyclo-G over G-CSF only.