Pharmagenesis Inc., a biotech company focused on anticancer therapies, entered a research collaboration with Fujisawa Pharmaceutical Co. related to immunosuppressants based on Chinese herbal remedies being developed by Pharmagenesis.

The immunosuppressants are triptolide derivatives. Triptolide is the primary active ingredient of a traditional Chinese medicinal plant called by the Latin binomial name Tripterygium wilfordii Hook F., which is a vine that grows wild in Asia, said John Musser, vice president of chemistry and intellectual property at Pharmagenesis, of Palo Alto, Calif.

"It's, of course, very important to our company to have our research validated by a large pharmaceutical company like Fujisawa," Musser told BioWorld Today.

Privately held Pharmagenesis would not disclose terms, other than to say that Fujisawa, of Osaka, Japan, has an option for the next year to make the decision to acquire exclusive, worldwide development and marketing rights to the compounds. Triptolide derivatives function by inhibiting cytokine production in T cells.

"There's been some tentative territories talked about and some tentative indications," Musser said.

Pharmagenesis said that the plant from which the compounds are derived has been used successfully in Chinese medicine for treatment of autoimmune diseases such as rheumatoid arthritis. The company said the compounds also may be effective in the prevention of organ transplant rejection and in dermatology.

"They are immunosuppressants, and Fujisawa certainly has a presence in immunosuppressants," Musser said, noting that "one could speculate" as to its reasons for being interested in the compounds. More specifically, he said that Fujisawa most likely would be interested in looking at the compounds in renal transplants.

Fujisawa already has a drug, Prograf, on the market for the prevention of rejection in liver and kidney transplants. The drug is available in 57 countries, and Pharmagenesis said the Japanese pharmaceutical company is looking for new compounds to be used in conjunction with or after use of Prograf.

Upon effecting the agreement, Fujisawa is scheduled to begin preclinical studies on the compounds, he said.

In activities other than cancer, Pharmagenesis uses purified extracts of plants from traditional Chinese medicine to develop drugs to treat cancer-related bone marrow suppression and the management of transplant rejection.

Last September, Pharmagenesis was awarded a new drug certificate by China's State Drug Administration for its plant-derived hematopoiesis enhancer, PG2, which is an adjunct to cancer therapy designed to restore bone marrow after chemotherapy.