Collection and Storage of Autologous Hematopoietic Stem Cells
Autologous procedures require collection of peripheral blood stem cells (PBSCs) from patients by the process of apheresis. Bone marrow can be used for the transplant, but PBSCs have been shown to lead to quicker recovery and less toxicity. Patients under consideration for autologous HCT are generally given chemotherapy to demonstrate tumor responsiveness and minimize risk of tumor contamination in their bone marrow. After a number of rounds of chemotherapy, they undergo the apheresis procedure, either as their blood counts recover from chemotherapy or during a break between chemotherapy treatments. Growth factors such as granulocyte colony-stimulating factor (G-CSF) are used to increase the number of circulating stem and progenitor cells (CD34+ cells). Collection centers monitor the CD34+ number in the patient and product each day to determine the best time to begin collection and when collection is complete. The collected PBSCs are cryopreserved for later use; after completion of an intensive preparative regimen using high-dose chemotherapy that varies according to tumor, the PBSCs are administered back to the patient at the time of transplant.
General Indications for Autologous Procedures/Preparative Regimens/Tumor Purging
In pediatrics, the most common autologous transplant indications are high-risk neuroblastoma, relapsed Hodgkin and non-Hodgkin lymphoma, high-risk and relapsed brain tumors, and relapsed or resistant germ cell tumors. Regimens specific to given tumors are described in disease-specific PDQ treatment summaries.
Preparative regimens for allogeneic transplant are mainly needed to ensure engraftment of the donor marrow or cord blood. Use of high-dose tumor-specific agents, however, has not shown benefit, especially if such agents add toxicity to the approach. Unlike allogeneic procedures, the tumor-specific activity and intensity of agents used for autologous regimens have been shown to be important in improving survival. One concern with autologous approaches to these and other tumor types has been the contamination of the collected stem cell product by persistent tumor cells. Although a wide variety of techniques have been developed to remove or “purge” tumor cells from products, most studies looking into these approaches have shown no benefit to tumor purging.
- Kreissman SG, Villablanca JG, Seeger RC, et al.: A randomized phase III trial of myeloablative autologous peripheral blood stem cell (PBSC) transplant (ASCT) for high-risk neuroblastoma (HR-NB) employing immunomagnetic purged (P) versus unpurged (UP) PBSC: A Children's Oncology Group study. [Abstract] J Clin Oncol 26 (Suppl 15): A-10011, 2008. Also available online. Last accessed December 11, 2014.