Clinical studies in over 300 patients demonstrated excellent safety without any serious adverse events at doses up to 100mg/week over months. No neutralizing antibodies were found in any of the patients. In previous toxicology studies of ACT-101 in rodents, neutralizing antibodies to AFP were detected. Toxicology studies were conducted in marmosets and showed low titers of neutralizing antibodies in about 50% of animals to recombinant human AFP following dosing once every 72 hours for 26 weeks (approximately 60 total doses).