Conventional chemotherapy doesn't cure multiple myeloma, a cancer of the plasma cells in bone marrow. Patients with myeloma who relapse after high-dose chemotherapy have few options for treatment. Thalidomide is the first new option for these patients in 35 years.

Thalidomide was banned in the US for several decades because it causes birth defects when taken by women during early pregnancy. For several years, scientists have been studying the drug as a possible cancer treatment because of its potential to stop the growth of tumors by cutting off their access to nutrients and oxygen. Angiogenesis, or growth of blood vessels, is essential to tumor growth, and thalidomide is believed to be an anti-angiogenic drug, meaning it can combat cancer by stopping the formation of new blood vessels and starving the tumor.

Two Patients Had Complete Remission

Of the 84 patients with myeloma who were studied, one-third were helped by thalidomide, now sold under the trade name Thalomid. Two patients went into complete remission. The study included patients who had previously experienced a relapse in their disease following high-dose chemotherapy.

"These numbers, although small, are very significant because we are talking about patients who have failed [to respond to] every other therapy including high-dose chemotherapy and bone marrow transplantation. Typically, these patients have no other options left," said Elias Anaissie, MD, co-author of the study and professor of medicine for the Myeloma and Transplantation Research Center at the University of Arkansas for Medical Sciences.

"This study suggests that there may be other ways to cause remission in multiple myeloma. Because thalidomide has a different mode of activity than chemotherapy, trying to understand how it works against myelomas may allow us to discover new drugs that are more effective than thalidomide," he added.

Findings Confirmed By Other Investigators

The study's findings have been confirmed by other investigators, said Bart Barlogie, MD, PhD, a co-author and director of the Arkansas Cancer Research Center. "Coupled with the fact that thalidomide does not appear to cause an array of adverse effects traditionally associated with chemotherapy, the study suggests that this drug could be an ideal agent for use in combination with other chemotherapeutic regimens. We are currently investigating this hypothesis," he said.

Chris Widnell, PhD, scientific program director for the American Cancer Society (ACS), emphasized that thalidomide is still in experimental stages but said this study offers very interesting approaches to a disease that has been resistant to treatment. Although thalidomide was initially chosen for the study because of its anti-angiogenic activity, testing the bone marrow of patients who responded to the drug suggests that some other mechanism of action is more likely.

"It is not clear how thalidomide is working in these situations where it has been successful. It is important for us to understand what actions of thalidomide are responsible for the benefit experienced in this study," Dr. Widnell said.

The ACS estimates 13,700 new cases of multiple myeloma will be diagnosed during 1999 and 11,400 deaths will result from the disease. Multiple myeloma accounts for about one percent of all cancers and 10 percent of cancers of the blood.