Swainsonine is an indolizidine alkaloid isolated from the fungus metharhizium anisopliae. It is an antineoplastic immunomodulator. Swainsonine restores the capacities of immunodeficient mice such that the growth and metastasis of implanted tumors are inhibited. The anti-metastatic effect may be the result of the stimulation of lymphocyte proliferation and augmentation of natural killer cell reactivity of the immune system. Swainsonine has been found to induce apoptosis in esophageal squamous cell carcinoma and human lung cancer cells as well as C6 glioma cells. In addition to its anti-proliferative effect on tumor cells, swainsonine has been found to potentiate cytotoxic effects of chemotherapeutic drugs such as paclitaxel and cisplatin.