Thymoctonan (also known as Thymic humoral factor γ2 ) is an octapeptide thymic hormone patented by Yeda Research and Development Co. Ltd. as an immunoregulatory agent. In preclinical models, Thymoctonan exerts potent anti-tumor activity in mice and significantly increases the specific cytotoxic response of immune spleen cells. In addition, Thymoctonan treatment improved the competence of immune spleen cells in adoptive immunotherapy when performed in combination with chemotherapy by melphalan. Besides that Thymoctonan enhancing the anti-viral potential of murine cytomegalovirus immune spleen cells. In fatal murine cytomegalovirus infection model, daily injections of Thymoctonan- enhanced murine cytomegalovirus immune spleen cells prevented the development of a fatal disease in 93% of the recipient mice.