German drugmaker Schering AG and U.S. biotech firm Genzyme Corp have seen good preliminary results in a study of the drug MabCampath to treat leukemia, Schering said in a statement.

Schering and Genzyme are co-developing MabCampath (alemtuzumab), which is marketed in the United States as Campath, for use against cancer and other diseases.

The drug is already approved to treat a type of blood cancer and the two companies are now studying it in a phase III trial of previously untreated patients with progressive B-cell chronic lymphocytic leukemia.

“Patients who received the monoclonal antibody MabCampath exhibited significantly higher overall and complete response rates, with a manageable safety profile,” than those treated with comparison drug chlorambucil, Schering said in a statement late on Saturday.

The interim results of the trial showed a nearly 30 percent greater overall response rate among patients treated with MabCampath than chlorambucil, it added.

Schering holds the worldwide marketing and distribution rights to the product, which is marketed in the U.S. by Schering affiliate Berlex Laboratories.

“Once the final data from the study’s primary endpoint of progression-free survival are available, Genzyme and Berlex expect to file an application seeking to expand the product’s current label to include previously untreated B-CLL patients who require therapy,” Schering said.

The trial involves 297 previously untreated patients with progressive disease at 44 medical centers in Europe and the United States, it added.

The most common side effects in the trial so far were fever, rigors, nausea, abnormally low blood pressure and vomiting.

Serious adverse events related to treatment occurred in 25 percent of MabCampath patients and 6 percent of patients on chlorambucil.

Chronic lymphocytic leukemia is the most prevalent form of adult leukemia, affecting approximately 120,000 people in Europe and the United States. The disease is most commonly diagnosed among people age 50 or older, Schering said.