A New Approach to Treating Melanoma
April 4, 2000 (San Francisco) -- Ever since researchers discovered that they could manufacture an artificial type of DNA that can mirror the body's own basic cell structure, they have been trying unsuccessfully to use the technology to target cancer. Now, however, a team of Austrian researchers presenting at a cancer research meeting here says it has found a way to use this technology to attack one of the deadliest of cancers -- advanced melanoma.
About 50,000 new cases of melanoma are diagnosed every year. If diagnosed early enough, the skin cancer does respond to treatment, but if it is diagnosed after it has spread too deeply into the skin or if it spreads to other sites in the body, it's deadly. Once melanoma has spread, it is highly resistant to treatment with anti-cancer drugs. The reason it survives the attack of chemotherapy drugs, says Burkhard Jansen, MD, is that the tumor produces high levels of a protein that shields the tumor and fights off the chemotherapy drugs. Jansen, who is an associate professor of clinical pharmacology at the University of Vienna, says a new drug, which is currently being called G3139 due to the fact that it is still so early in the research process, actually turns off this shield and allows the cancer-killing drugs to attack the tumor.
Jansen says that several patients who were given G3139 before they were given the usual chemotherapy had a marked reduction in the size of their tumors. One patient, a 90-year-old woman, had a complete response and has been free of disease for three months, he says. Another five patients had a variety of responses ranging from shrinkage of the tumor to half its original size to stopping progression of the melanoma.
In all, 14 patients with advanced disease were treated with the drug, Jansen says. He tells WebMD that the expected survival of these patients is "about four to six months after diagnosis." On average, the patients who have responded to the treatment have sustained that response for nine months, he says.
Jansen says a large-scale trial of the drug is set to start within the next two months. That trial will enroll 270 patients and will compare outcomes of patients treated with traditional chemotherapy alone to patients who receive G3139 before getting chemotherapy.
Peter Jones, PhD, says, "If these results can be reproduced to show that the [drug] is definitely getting to the tumor, this could be a very exciting finding." He says the difficulty with this new technology is that, while results are very good in the lab, actually getting the drug to the tumor in a person has been disappointing. Jones is the program chairman of the American Association for Cancer Research meeting.
Jansen says G3139 was given in the vein for five days and that treatment was then followed with standard chemotherapy. G3139 is given before each additional chemotherapy cycle. "Some of the 14 patients in this trial had as many as 10 chemotherapy cycles," he says.
He adds the only side effects noted were fever, flushing, and rash. Two patients who received the highest doses had temporary liver function problems, he says.
Although the drug will continue to be studied in melanoma patients, Jansen says that this new drug may also be useful for lymphomas and prostate, colon, breast, and small cell lung cancers.