In 4 out of 5 PDAC patient samples tested, stimulation of NK cells with IL-15 resulted in a statistically significant increased capacity of killing of autologous PSC derived from tumor tissue, ranging from 23.8% to 52.9% killing after stimulation (2.7- to 6.9-fold increase; p < 0.05) at an E:T ratio of 5:1. The gene discussed is IL15; the disease is neoplasm.