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Sea Squirts: Cancer Fighters From the Sea
Nov. 15, 2000 (Amsterdam) -- The Creature from the Black Lagoon was scary, dangerous, and something to avoid. Now some deep sea dwellers are a welcome sight for cancer researchers. They're called sea squirts, and clumps of the creatures may some day play a critical role in fighting cancer.
One species of sea squirt gathers in clusters, looks like a sponge, and contains a cancer-fighting substance called ecteinascidin-743. The extract is being used to treat patients with breast cancer, and preliminary studies have shown it can cause tumors to shrink. Researchers discussed their studies at a meeting of cancer experts here.
Cecilia Guzman, MD, head of clinical research and development at Madrid-based Pharma Mar, says ET-743 is derived by crushing bunches of sea squirt found in the Caribbean and then harvesting the active ingredient. In the trials, 16 of 26 patients benefited -- either by partial shrinking of the tumors or by stopping the progression of the disease for months.
Patients getting ET-743 therapy already had been treated with standard chemotherapy drugs, yet their cancer still progressed. "This ongoing study confirms the clinical activity of ET-743 in patients with advanced breast cancer," Guzman tells WebMD.
Guzman suggested that ET-743 might have a role in treating cancer by combining it with other chemotherapy drugs. Researchers are especially interested in ET-743's activity on a molecular level. It appears to disrupt cancer cells' ability to activate certain genes in the body that can reduce the effectiveness of cancer-fighting substances.
She also reports on another Pharma Mar drug, aplidine, extracted from a Mediterranean sea squirt. Laboratory studies showed that aplidine prevents cancer cells from dividing -- in effect stopping their growth. This drug also disrupts the chain of events that allows tumors to build the blood vessels required for nutrition and growth.
The drug, given through the vein, has shown effectiveness in patients with advanced melanoma -- the deadliest of skin cancers, kidney cancer, and thyroid cancer. And about 35 patients were enrolled in the studies designed to figure out the best dose for treating cancer patients.
"It's not surprising to find these compounds from animals in the sea," says Martin Langer, MD, a scientist with Biotechnology Research and Information Network in Zwingenberg, Germany. "Two-thirds of the world's life forms live in the sea, and only a few of them have been cultivated for use as possible medicines," he tells WebMD.
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