SYDNEY, Australia ¿ BresaGen Ltd., a biotechnology company in Adelaide, South Australia, has started a Phase I trial for an anticancer drug, a modified form of a natural human hormone.

The study of the protein, called E21R by the company, will involve 18 end-phase cancer patients, mainly myeloid leukemia and breast cancer patients, at the Royal Adelaide Hospital.

Although the study will be of patients who have not responded to conventional treatments, it will be used mainly to determine dose tolerance for the molecule. Peter Wigley, project coordinator for BresaGen, said that the doses will start at 10 micrograms per kilogram of body weight and move up to one milligram per kilogram.

The Phase I trial will take most of this year and, if successful, the company will move on to a Phase II trial next year. No details of that study have been worked out, but it could involve 30 to 40 patients, the company said.

Meera Verna, general manager of BresaGen¿s protein pharmaceutical division, said that although the Phase I trial was primarily a safety study, it was possible that some patients might benefit from the drug during the trial.

The drug was identified in 1993 at the Adelaide Hanson Centre for Cancer Research, an offshoot of the Institute of Medical and Veterinary Science, in Adelaide, as a modification of the molecule granulocyte macrophage colony stimulating factor, which is involved in the development of red blood cells. By systematically changing the molecule and then testing the result, Angel Lopez and Mathew Vadas at the Hanson Centre found a variation that would bind to blood cancer cells and cause the death of the cell.

Wigley said that the modification involved a change in just one of the amino acids in the molecule. The modified form of the molecule is protected by patents in the U.S., Australia and New Zealand, and patent coverage is being sought in Europe and other countries. BresaGen is funded by private investment and government grants, and has no immediate plans to list on the stock exchange.