Efficacy of acemannan in treatment of canine and feline spontaneous neoplasms. Mol Biother. 1991 Dec;3(4):207-13. Twelve animals showed obvious clinical improvement as assessed by tumor shrinkage, tumor necrosis, or prolonged survival; these included five of seven animals with fibrosarcomas. It is believed that acemannan exerts its antitumor activity through macrophage activation and the release of tumor necrosis factor, interleukin-1, and interferon.