Vical Inc. said Tuesday that Centocor Inc. expanded an option and license agreement to use Vical's naked DNA technology to develop DNA vaccines for cancer.

The expansion of the agreement, first established in 1998, will provide an undisclosed up-front payment to Vical, and it could lead to milestone payments and royalties, said Alan Engbring, director of investor relations for San Diego-based Vical. Centocor is a Johnson & Johnson company.

"They have expanded the agreement beyond what the original agreement called for, but the specifics we have agreed not to discuss," Engbring said. "They have not named any targets."

There is no defined endpoint to the agreement.

"It is an ongoing relationship," Engbring said.

The naked DNA technology is a gene delivery technology, and it involves the direct injection of plasma DNA, he said.

"When you're using it for cancer vaccines, you would use a tumor-specific antigen and deliver the gene that encodes for that antigen, which triggers an immune response against the cancer," he said.

However, the technology can be used in infectious disease to deliver therapeutic proteins, or antigen proteins, he said.

Vical has agreements with other companies that are developing therapeutic and vaccine product candidates for infectious diseases and metabolic disorders. The companies with which Vical has existing agreements include Merck & Co. Inc., of Whitehouse Station, N.J., which is developing a vaccine to combat HIV, among other efforts; Aventis Pasteur, of Lyon, France, for a tumor-associated antigen therapeutic vaccine; and Aventis Pharma AG, of Frankfurt, Germany, for a cardiovascular therapeutic vaccine.

Internally, Vical has the immunotherapy Allovectin-7 in Phase II and Phase III studies in patients with metastatic melanoma and in Phase II studies in patients with head and neck cancer. Allovectin-7, which is injected directly into tumors, is a DNA/lipid complex containing the human gene encoding HLA-B7, which is seen infrequently in the human population, the company said.

"Allovectin has completed the Phase III study, and we are now collecting data from that study and expect to have completely adjudicated results in the second half of the year," Engbring said. "At that point, we will decide whether the data are sufficient to support a [biologics license application]."

Another immunotherapy, Leuvectin, is in Phase II studies in prostate cancer. The company said Leuvectin uses a lipid-DNA complex to stimulate an immune response against cancer cells.

Engbring said Vical would have "information about the future of that program in the second half of this year."

In April 2001, Vical ended a Phase II study of Leuvectin in metastatic kidney cancer after failing to achieve the desired results with 37 patients in what was planned to be an 80-patient trial. (See BioWorld Today, April 23, 2001.)

Vical's stock (NASDAQ:VICL) fell 3 cents Tuesday to close at $5.60.