Is thiotepa-based conditioning effective before stem cell transplant in ALL?

This study examined the use of thiotepa-based conditioning before stem cell transplantation in acute lymphoblastic lymphoma (ALL). This study concluded that this treatment may be as effective as the currently used conditioning combination.

Before undergoing a stem cell transplant, patients must undergo conditioning. This is a treatment used to kill cancer cells and to prepare the body to allow new stem cells to grow. Conditioning for ALL patients usually involves the chemotherapy cyclophosphamide (Cytoxan) and total body irradiation (cyclo-TBI). This type of conditioning is very effective, but is also associated with many long-term side effects. These include fertility problems, high blood pressure, and the risk of other cancers.

Thiotepa (Thioplex) is a chemotherapy agent that has been used in other types of cancer. It has recently been shown to be effective in acute myeloid leukemia and certain types of lymphoma. It is not clear whether thiotepa-based conditioning is as effective as cyclo-TBI in ALL.

This study examined the records of 720 ALL patients who underwent stem cell transplantation. 180 patients were treated with thiotepa-based conditioning (group 1). 540 were treated with cyclo-TBI (group 2). Patients were followed for 2 years.

Engraftment (production of new stem cells) occurred 15 days after transplant for group 1. This was significantly faster than for group 2 (17 days). Two-year overall survival rates (time from treatment until death from any cause) were not significantly different. Group 1 patients were 78% more likely to relapse, but this did not affect overall survival. After two years, 33% of group 1 and 39% of group 2 were leukemia free.

There were no significant differences between the groups in the rate of graft-versus-host disease (when the transplanted stem cells attack healthy tissue).

This study concluded that thiotepa-based conditioning may be as effective as cyclo-TBI.