Neurocrine Biosciences Inc. and Taisho Pharmaceutical Co. Ltd. started a pivotal Phase IIb trial of NBI-6024, a therapeutic vaccine candidate for Type I diabetes.

Neurocrine, of San Diego, said a second Phase IIb clinical trial would begin sometime this year. If both trials are completed successfully, the company hopes to use the results as the basis for a new drug application with the FDA. The trials are expected to take three years to complete, including one year it is expected to take to complete enrollment of about 400 adults and adolescent patients with new-onset Type I diabetes, said Henry Pan, executive vice president and chief medical officer for Neurocrine.

Neurocrine will receive an undisclosed milestone payment from Tokyo-based Taisho. The two companies entered into a collaboration valued at up to $45 million to Neurocrine in January 2000, which included an up-front payment of several million dollars. (See BioWorld Today, Jan. 7, 2000.)

Neurocrine in the original deal licensed European and Asian commercialization rights to its altered peptide ligand (APL) to Taisho. The agreement was expanded in December 2000 to give Taisho rights to develop and commercialize the peptide in North America and other countries outside Europe and Asia. (See BioWorld Today, Dec. 13, 2000.)

In Type I diabetes, patients are treated primarily with insulin replacement, since the pancreas is no longer able to secrete insulin, but there are no real therapies, Pan said.

NBI-6024 is based on Neurocrine’s APL technology. In the case of Type I diabetes, the beta-islet pancreatic cells, which are responsible for the production of insulin, are the targets. The company’s approach is to engineer one of the dominant pancreatic antigens so that it is still recognized by the pathogenic immune cell as being foreign; however, it serves to elicit a protective immune response by down-regulating the immune-mediated destructive process. As a result, the B-islet cell and its insulin-producing capability are preserved.

The Phase IIb trial is a randomized, double-blind, placebo-controlled study to evaluate the safety, efficacy, tolerability and pharmacodynamic activity of three doses of NBI-6024 compared to placebo. The primary endpoint of the trial is to evaluate the effect of repeated administrations of NBI-6024 in preserving endogenous insulin secretion as measured by C-peptide levels. The trial will be conducted in about 40 sites in the United States, Canada, Europe and South Africa.

Neurocrine focuses on neurological and endocrine diseases and disorders, with product candidates in insomnia, anxiety, depression, malignant brain tumors and peripheral cancers, diabetes, multiple sclerosis, irritable bowel syndrome, eating disorders, pain, stroke and certain female health disorders.

In November, Neurocrine began its first pivotal Phase III trial of NBI-34060, a non-benzodiazepine compound that acts against chronic insomnia through a specific site of the GABA-A receptor.

Neurocrine’s stock (NASDAQ:NBIX) rose 68 cents on Thursday to close at $51.25.