Administration of Donor T Cells With the Caspase-9 Suicide Gene

Plain-language summary

Patients will be receiving a stem cell transplant as treatment for their disease. As part of the stem cell transplant, patients will be given very strong doses of chemotherapy, which will kill all their existing stem cells. A close relative of the patient will be identified, whose stem cells are not a perfect match for the patient's, but can be used. This type of transplant is called "allogeneic", meaning that the cells are from a donor. With this type of donor who is not a perfect match, there is typically an increased risk of developing GvHD, and a longer delay in the recovery of the immune system. GvHD is a serious and sometimes fatal side-effect of stem cell transplant. GvHD occurs when the new donor cells (graft) recognize that the body tissues of the patient (host) are different from those of the donor. In this study, investigators are trying to see whether they can make special T cells in the laboratory that can be given to the patient to help their immune system recover faster. As a safety measure, we want to "program" the T cells so that if, after they have been given to the patient, they start to cause GvHD, we can destroy them ("suicide gene"). Investigators will obtain T cells from a donor, culture them in the laboratory, and then introduce the "suicide gene" which makes the cells sensitive to a specific drug called AP1903. If the specially modified T cells begin to cause GvHD, the investigators can kill the cells by administering AP1903 to the patient. We have had encouraging results in a previous study regarding the effective elimination of T cells causing GvHD, while sparing a sufficient number of T cells to fight infection and potentially cancer. More specifically, T cells made to carry a gene called iCasp9 can be killed when they encounter the drug AP1903. To get the iCasp9 gene into T cells, we insert it using a virus called a retrovirus that has been made for this study. The AP1903 that will be used to "activate" the iCasp9 is an experimental drug that has been tested in a study in normal donors with no bad side-effects. We hope we can use this drug to kill the T cells. The major purpose of this study is to find a safe and effective dose of "iCasp9" T cells that can be given to patients who receive an allogeneic stem cell transplant. Another important purpose of this study is to find out whether these special T cells can help the patient's immune system recover faster after the transplant than they would have otherwise.

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