The Food and Drug Administration's decision to allow new patient enrollment in two Phase 3 clinical trials of the therapeutic vaccine, Canvaxin, removes an irksome roadblock for the privately held biotechnology company.

The FDA held up the studies last May, largely over technical manufacturing issues. The vaccine is designed to treat melanoma, a deadly skin cancer that claims about 8,000 American lives each year.

Phase 3 trials are the last hurdle before a company can seek regulatory approval to sell a new drug. Prior to the FDA's May action, CancerVax had hoped to complete enrollment of its final studies this year – but the regulatory hold put that goal in limbo.

Also placed in limbo because of the uncertainty surrounding the regulatory action were CancerVax's efforts to raise new capital to fund the studies.

The company now expects to finish recruiting patients for the two studies in 2004, chief executive David Hale said. CancerVax had already enrolled 900 of the proposed 1,700 volunteers; the FDA allowed those patients to continue receiving treatment during the stay on enrollment.

"This action by the FDA will allow CancerVax to move forward rapidly," said Hale, whose company employs 130. "One of the key issues in getting any biologic approved is the manufacturing process, and based on the data we've developed for the FDA we believe we have a road map for meeting the FDA's requirements."

CancerVax is one of scores of biotech companies around the country that are developing cancer vaccines. Unlike traditional vaccines that provide protection against the flu and other diseases, most cancer vaccines are aimed at patients who are already battling cancer.

Several San Diego County companies are testing vaccines to treat lymphoma, skin cancer, colorectal cancer and lung cancer, including Favrille, CancerVax, Epimmune and NovaRx. Cancer vaccines are designed in one way or another to teach the body's immune system to recognize and kill cancer cells.

CancerVax's closest competitor, New York-based Antigenics, has a "personalized" melanoma vaccine, made from each individual patient's own cancer tumor, in Phase 3 development.

In contrast, CancerVax is developing a mass-produced, off-the-shelf variety that combines several antigens – substances that flag the immune system's cancer-fighting defenses – common to most skin cancer tumors.