Sizofiran (Schizophyllan, SPG, Sonifilan, Sizofilan) is a soluble beta-D-glucan produced by the Basidiomycetes fungus, Schizophyllum commune Fries, with potential immunomodulating and antitumor activities. Although sizofiran’s exact mechanism of action has yet to be fully elucidated, this agent appears to stimulate the immune system by increasing cytokine production, activating macrophages and Langerhans cells and enhancing the activity of polymorphonuclear leukocytes (PML) and natural killer (NK) cells. Sizofiran was found rather ineffective against gastric cancer, but extended survival time in patients with head and neck cancer. In cervical cancer, Sizofiran prolonged survival and time to recurrence for stage II cases but not stage III, and showed added effectiveness when injected directly into the tumor mass. Sonifilan is used as a biological response modifier (BRM) with radiation therapy for cancer treatment in Japan. It was launched for cervical cancer in South Korea in 1998.