Comparing conditioning regimens for patients with acute myeloid leukemia who will receive a transplant

This study aimed to investigate the long-term survival outcomes for patients with acute myeloid leukemia receiving conditioning regimen involving fractionated total body irradiation combined with cyclophosphamide or etoposide before transplant.  

This study concluded that this conditioning regimen is safer and more effective than intravenous busulfan based conditioning regimens.  

Allogenic hematopoietic stem cell transplantation (allo-HSCT) is a procedure in which a person receives blood-forming stem cells from a genetically similar, but not identical, donor. This is often a sister or brother but could be an unrelated donor. Cyclophosphamide (Cytoxan) and etoposide (Etopophos) are chemotherapies. Busulfan (Bulsufex) is a chemotherapy drug used before HSCT to treat blood cancers. Fractionated total body irradiation (FTBI) is a form of radiotherapy used to prepare patients for HSCT. 

Cyclophosphamide/etoposide combined with FTBI or with intravenous busulfan (IVB) is the main conditioning regimen for allo-HSCT in young patients with acute myeloid leukemia (AML). A conditioning regimen prepares the patient's body for the transplant. It also aims to prevent the rejection of transplanted cells.  

Studies have suggested that IVB could be the preferred conditioning regimen for patients with AML. However, higher rates of sinusoidal obstruction syndrome (SOS) are seen in patients treated with busulfan-based regimens. SOS is a potentially fatal form of liver injury that occurs after drug exposure. Therefore, it was unknown if FTBI would be a safe and effective alternative to busulfan in patients with AML undergoing allo-HSCT. 

This study involved 167 patients with AML. All patients were in first or second complete remission and underwent alloHSCT. Patients received a conditioning regimen with FTBI and cyclophosphamide if the transplant was coming from an unrelated donor. Patients received a conditioning regimen with FTBI and etoposide if the transplant was coming from a related donor. Both groups of patients also received tacrolimus (Prograf) and sirolimus (Rapamune) to prevent graft-versus-host-disease (GVHD). GVHD is where the transplanted cells attack the patient's cells.  

The 6-year overall survival rate was 60%. The 6-year non-relapse mortality (death rate not related to a relapse) rate was 15%. Survival without GVHD and without a relapse was 45% at 1 year and 39% at 2 years.  

Tacrolimus and sirolimus preventative treatment was associated with high rates of chronic GVHD (71%). The FTBI regimen was associated with a low risk of long-term toxicities. 

This study concluded that FTBI based conditioning regimen is safer and more effective than IVB based conditioning regimens in young adults with AML.  

This study did not have a control group for comparison. Further studies are needed.