Macrophages that received the Il9r-siRNA nanoparticles showed substantial reduction of IL-9R expression compared to cells receiving the Scr-siRNA nanoparticles, indicating successful inhibition of Il9r expression in vivo and demonstrated significantly reduced tumor growth on day 21 (Fig. 9i, j and Supplementary Fig. 6d-e). The gene discussed is IL9R; the disease is neoplasm.