A plant-derived recombinant human glucocerebrosidase enzyme--a preclinical and phase I investigation

Abstract

Gaucher disease is a progressive lysosomal storage disorder caused by the deficiency of glucocerebrosidase leading to the dysfunction in multiple organ systems. Intravenous enzyme replacement is the accepted standard of treatment. In the current report, we evaluate the safety and pharmacokinetics of a novel human recombinant glucocerebrosidase enzyme expressed in transformed plant cells (prGCD), administered to primates and human subjects. Short term (28 days) and long term (9 months) repeated injections with a standard dose of 60 Units/kg and a high dose of 300 Units/kg were administered to monkeys (n = 4/sex/dose). Neither clinical drug-related adverse effects nor neutralizing antibodies were detected in the animals. In a phase I clinical trial, six healthy volunteers were treated by intravenous infusions with escalating single doses of prGCD. Doses of up to 60 Units/kg were administered at weekly intervals. prGCD infusions were very well tolerated. Anti-prGCD antibodies were not detected. The pharmacokinetic profile of the prGCD revealed a prolonged half-life compared to imiglucerase, the commercial enzyme that is manufactured in a costly mammalian cell system. These studies demonstrate the safety and lack of immunogenicity of prGCD. Following these encouraging results, a pivotal phase III clinical trial for prGCD was FDA approved and is currently ongoing.

Trial registration: ClinicalTrials.gov NCT00258778.

Conflict of interest statement

Competing Interests: David Aviezer, Einat Brill-Almon, Yoseph Shaaltiel, Sharon Hashmueli, and Daniel Bartfeld are all employed by Protalix (http://www.protalix.com) the company which sponsored the study and also hold the license for the product. As such holds shares in the company. As aponsors and funders of the study Protalix employees (listed above) had a role in study design and review of data analysis. Eithan Galun was an adviser to Protalix. Ari Zimran is a paid consultant of Protalix. All other authors declare no competing financial interests.

Figures

Figure 1. The combined pharmacokinetic profile of 5 subjects at 30 units/kg and 60 units/kg.

Blood samples were collected prior to dosing (0) and at predetermined time points after start of infusion. Plasma was analyzed for prGCD concentration using a validated immunoassay. Error bars represent standard deviation. Plasma analysis data were analyzed by Noncompartmental pharmacokinetic analyses (NCA) using WinNonlin® software.