In other clinical studies using T cells, some investigators found that giving chemotherapy before the T cell infusion can improve the amount of time the T cells stay in the body and therefore the effect the T cells can have. Giving chemotherapy before a T cell infusion is called lymphodepletion since the chemotherapy is specifically chosen to decrease the number of lymphocytes in the body. Decreasing the number of patient's lymphocytes first should allow the T cells we infuse to expand and stay longer in your body, and potentially kill cancer cells more effectively.