For patients with leukemia and other hematological malignancies, donor hematopoietic stem cells can recognize and attack remaining cancer cells after chemotherapy. But residual cancer cells’ immune-suppressing effects can thwart these transplants and lead to eventual relapse, requiring a donor lymphocyte infusion. A new study suggests that a treatment as simple as sodium bicarbonate—better known as baking soda—can potentially boost donor lymphocytes’ ability to overcome relapse after stem cell transplants.