PARIS - Meristem Therapeutics, a French biotechnology company specializing in the production of therapeutic proteins and active substances from plants, successfully completed a Phase I trial of a new therapeutic agent for use in the treatment of cystic fibrosis. It is the first drug developed from plant engineering in Europe to have been taken into clinical trials.

Plant engineering is the trademarked term given by Meristem to the downstream extension of its primary technology, molecular farming, which denotes the cultivation of genetically modified plants for the production of recombinant proteins with therapeutic applications. This technology enables Meristem to produce unlimited quantities of complex proteins at low cost. The protein tested in this first clinical trial was gastric lipase, which Meristem obtained from genetically modified maize seeds.

CEO Bertrand Mirot told BioWorld International that the company has two other products in its pipeline that could be taken into clinical development within a year or two. One is human collagen, a protein used in skin repair and reparative surgery, and the other is human lactoferrin, a protein secreted in mother's milk that protects against infections. Both have been successfully produced in maize and tobacco.

The Phase I trial of gastric lipase, which was carried out on eight healthy volunteers in Manchester, England, demonstrated its safety and acceptability in both single and repeated daily oral doses. According to Mirot, the company plans to embark on a Phase II trial this autumn with two objectives in mind: "To offer a definite therapeutic advance in the treatment of cystic fibrosis and to position plants as a reference system in the production of proteins of pharmaceutical value." And, he added, "No other production system could be envisaged for lipases. Plants are a technological leap forward in the production of less costly and safer therapeutic proteins."

The viability of molecular farming technology was originally demonstrated by Meristem Therapeutics' parent company, the French seed producer Limagrain, before it spun Meristem off as a separate subsidiary in 1998. Limagrain had succeeded in cultivating genetically modified tobacco to produce both gastric lipase and synthetic human hemoglobin. Tobacco is not a suitable plant for mass production, however, insofar as it does not yield sufficient quantities of proteins, so Meristem has developed other applications of its core technology for managing the genetic transformation of various plants depending on the proteins required. At its premises in Clermont-Ferrand in central France, the company has established an industrial-scale extraction/purification plant complying with GMP standards for purifying large quantities of pharmaceutical-grade recombinant protein from plants.

Mirot also disclosed that Meristem was about to sign a co-development and marketing agreement for gastric lipase with "a leading pharmaceutical company in Europe. The agreement will be signed in the coming weeks and we are already working with them." He added that the company's involvement in the product's clinical development would start with the Phase III trial at the latest, and possibly during Phase II. In 1998 Meristem entered into a research collaboration covering gastric lipase with Parke-Davis, but according to Mirot, the U.S. company pulled out of the research program after its takeover by Pfizer Inc., for which gastroenterology is not a specialist therapeutic area.

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