Disclosed herein are methods and devices for stimulating an immune response to a disease in a subject, which involves passing sub-microsecond long pulses of electric fields having an amplitude between 5 kV/cm and 68 kV/cm through an abnormal growth of a subject sufficient to suppress myeloid-derived suppressor cell (MDSC) or regulatory T cell (Treg) production, increase adenosine triphosphate (ATP) or high mobility group box 1 (HMGB1) production, or stimulate dendritic cell activation in the subject.