During autologous HSCT, an increased content of CD4+Foxp3+ cells (6.7%) in the peripheral blood of patients with multiple myeloma on the day of graft engraftment led to a relapse or progression of the tumor disease within 12 months after transplantation [74], which is possibly associated with the suppression of T-effector cell expansion at an early stage of immune reconstitution, while no cases of acute and chronic GVHD were recorded. The gene discussed is FOXP3; the disease is graft versus host disease.