Agent from the sea has antitumor properties.

A very preliminary human trial of a compound extracted from a marine animal hints that this agent may have a future as an antitumor drug.

While the rain forest is commonly thought of as a source of novel drugs, this study shows that the sea also may provide oncologists with a rich source of cancer-fighting compounds, comments Andrew S. Kraft of the University of Alabama at Birmingham. The agent, bryostatin 1, is obtained by grinding and purifying a small sea creature called Bugula neritina.

A raft of studies had previously demonstrated bryostatin 1's cancer-killing muscle in the test tube or in laboratory animals. For example, scientists have shown that it can halt the proliferation of human leukemia cells growing in a petridish. in addition, the compound has been shown to shrink skin tumors in mice.

"This study is the first to use the drug in humans," says Philip A. Philip, formerly at Churchill Hospital in Oxford, England, who coauthored the report in the Nov. 17 JOURNAL OF THE NATIONAL CANCER INSTITUTE.

Before they can test its efficacy in humans, Philip and his colleagues must show that bryostatin 1 is safe. So the team designed a trial in which they gave verious doses of the drug to 35 people with a variety of advanced malignant tumors. Not all recruits were candidates for or had failed conventional anticancer treatments, Philip notes.

The most notable side effect of the new drug seems to be muscle pain, which was severe enough to necessitate stopping treatment in six patients, Philip reports. Patients did not experience the nausea or vomiting associated with the all-out blitz of chemotherapy, he says.

Although this trial is not designed to determine efficacy, bryostatin 1 did show a glimmer of effectiveness in two people suffering from malignant melanoma, a deadly type of skin cancer that is very resistant to treatment, says Philip, now at the University of Texas M.D. Anderson Cancer Center in Houston. After experimental treatment with bryostatin 1, the patient's tumors shrank by at least 50 percent, a remision that lasted up to 10 months in one case.

Bryostatin 1's mechanism of action is likely to be complex. For example, laboratory studies have demonstrated that this compound stimulates the activity of protein kinase C, an enzyme that regulates cancer cell growth, notes Kraft, who wrote an accompanying editorial. What's more, Philip adds, bryostatin 1 may trigger the immune system's attack on malignant cells.