http://www.boston.com/dailyglobe2/153/business/Therion_vaccine_shows_promise_in_cancer_fight+.shtml

Therion vaccine shows promise in cancer fight

Therapy designed as an immune response trigger

By Naomi Aoki, Globe Staff, 6/2/2003

In a promising sign in the fight against cancer, a vaccine stopped the progression of the disease in 40 percent of patients suffering from advanced colorectal, pancreatic, breast, and lung cancers, according to a study presented yesterday at the annual meeting of the American Society of Clinical Oncology in Chicago. 

The study included 58 patients deemed terminal because they had exhausted their treatment options. The positive results from the vaccine, made by Therion Biologics Inc. of Cambridge, add to mounting evidence that the immune-boosting power of vaccines will prove an important and effective weapon in fighting and, one day, possibly preventing a wide range of cancers.

The findings come as other approaches are also beginning to show significant cancer-fighting results after decades of trial and failure. Drugs from Genentech Inc., AstraZeneca, and ImClone Systems Inc. showed promise for colorectal cancer patients in shrinking tumors, slowing the progression of disease, and potentially extending life, according to clinical trial data released yesterday.

''We're starting to see a lot of learnings over the last five years come together all at once,'' said Dr. Mitchell H. Gold, chief executive of Dendreon Corp., a Seattle company developing cancer vaccines. ''It's an extremely exciting time for cancer research.''

For decades, researchers hypothesized that vaccines could trigger the body's own immune system to recognize and aggressively attack tumor cells. But even as knowledge grew about cancer and the body's natural immune response, studies failed to make the link between triggering a desired immune response and visible improvements in patients, such as longer lives.

Last year, Dendreon became the first to provide data showing its vaccine triggered a powerful assault on cancer by boosting a person's immune response. The vaccine, Provenge, halted the progression of the disease in about 35 percent of patients after six months compared to only 4 percent of patients who were given a placebo, or a dummy drug.

''It was a turning point for the industry as a whole,'' Gold said. ''And it was a great win for patients.''

Jennette Williams, who lives in Alexandria, Va., was diagnosed with colon cancer a decade ago. Over five years, she underwent three surgeries, first to remove part of her colon, then her ovaries and eventually her uterus. Each surgery was followed by radiation and chemotherapy, but the cancer always came back. When it reappeared 2 1/2 years ago, she volunteered for the study of Therion's cancer vaccine, TRICOM.

The vaccine is designed to stimulate an immune response against carcinoembryonic antigen, or CEA, a protein found on the surface of tumors in more than 90 percent of colon and pancreatic cancers and more than 65 percent of breast and lung cancers. Since going on the vaccine, Williams said, her cancer has remained stable. The 72-year-old hasn't noticed symptoms from the cancer or side effects from the vaccine. She golfs weekly, helps care for her six grandchildren, and dances.

''I did this because I wanted to be able to give somebody else some hope that things aren't as gloomy as they seem, that more and more is becoming available to fight cancer,'' Williams said.

Despite a growing body of promising vaccine results, physicians caution that much work remains to be done before these vaccines are proven to work. About a half-dozen companies like Dendreon and Therion hope to begin marketing their vaccine therapies in the next two to three years. But many drugs fail in late stages of development. Further down the road, researchers hope the vaccines may also be used to prevent cancer in people at high risk for the disease.

''The biggest challenge is always finding something that works well,'' Dr. Louis M. Weiner, chairman of medical oncology at Fox Chase Cancer Center.

''We're still in the data-gathering phase. But I think there is better reason to be hopeful now than at any time in the history of vaccine therapies for cancer.''

In the 12 years since Therion was founded, the company has tested 25 different prototypes of its cancer vaccines in many small studies. Like others in the field, it has shown that its vaccines trigger the desired immune response in patients, but Therion has yet to prove its vaccines help shrink tumors or increase survival rates. Researchers caution that results from this most recent study must also be confirmed in larger clinical trials before they are conclusive. But along with other studies, the results are fueling hopes that the promise of cancer vaccines could soon become a reality.

Of the 58 patients in the Therion study, 23 saw their disease stabilize for a period of at least four months. Of those, five saw a reduction in the amount of tumor protein circulating in their blood. In one woman with small-cell lung cancer, the vaccine eliminated all signs of the disease. Patients reported some mild side effects, including fever, skin reactions, and swollen glands.

Therion has already created another version of TRICOM that it hopes will be even more effective than the current vaccine appears to be. That vaccine, known as PANVAC, is designed to stimulate an immune attack on CEA and another protein found on the surface of cancer cells, known as MUC-1. The company plans to take the vaccine into a large clinical trial next year.

Later this year, it plans to begin a large clinical trial for a prostate cancer vaccine based on similar technology.

''The really important thing about this trial is that it continues to show this kind of therapy can work,'' said Dr. John Marshall, an associate professor of medicine at Georgetown University and the lead investigator on this study.

''It shows that we are getting smarter about how to build these vaccines, continues to build a case for their use in a much broader population of patients.''

Naomi Aoki can be reached at naoki@globe.com. Material from Globe wire services was used in this report.

This story ran on page C1 of the Boston Globe on 6/2/2003.
© Copyright 2003 Globe Newspaper Company.