Developments to Watch
Introduction
At the annual meeting of the American Society of Clinical Oncology (ASCO) in Orlando May 18-21, 25,000 cancer researchers discussed and debated the latest advances in treatment and prevention. There were no bold claims for cures. But data from human clinical trials continue to reveal incremental progress. Senior Writer Catherine Arnst reports.
Chemo's Arsenal Could Get a Booster Shot
Although high-tech cancer drugs are in the pipeline, chemotherapy remains the primary treatment for most patients. But even chemo can be improved on, as a large study of the Sanofi Pharmaceuticals drug oxaliplatin showed. The Food & Drug Administration rejected oxaliplatin two years ago, but it is widely used in Europe. The U.S. study presented at ASCO showed it to be significantly more effective against colon cancer than standard drug therapies.
Half of 795 patients got the two standard chemo drugs used against colon cancer, while the other half got the two plus oxaliplatin. Dr. Richard M. Goldberg of the Mayo Clinic, the lead investigator of the trial, says that after one year of treatment, 71% of patients who received the new combination were still alive, compared with 58% of patients on standard treatment. Dr. Leonard Saltz of Memorial Sloan-Kettering Cancer Center, a leading colon-cancer specialist, says the survival results are the most dramatic he has seen in a colon-cancer trial.
Dr. Alain Herrera, head of oncology marketing for Sanofi, says oxaliplatin has been available throughout Europe since 1999. The FDA asked for more data when it rejected the drug in 2000 because the European trials did not follow U.S. guidelines. The agency agreed in early May to reconsider oxaliplatin on an expedited basis.
Vaccines You Get After You Have Surgery
Vaccinating cancer patients after their initial treatment may be one way to prevent the disease from recurring. Encouraging data were presented in Orlando for two experimental vaccines aimed at prostate cancer, which afflicts millions, including former New York Mayor Rudolf Giuliani. Therion Biologics in Cambridge, Mass., designed its Prostvac vaccine to prompt an immune response against any cells that display a protein called prostate-specific antigen (PSA), which is overproduced by prostate-tumor cells. The vaccine was tested on 70 patients who had undergone surgery or radiation, with intriguing results. The trial subjects' PSA levels were already rising, usually a sign that the disease will recur. But at the two-year mark, the vaccine had halted the PSA rise in 53% of the patients. Plus, 78% of the patients remained free of the disease.
Cell Genesys in Foster City, Calif., has a vaccine, called GVAX, that is made from inactive tumor cells that are genetically modified to secrete an immune hormone. Researchers tested the vaccine on 34 patients whose prostate cancer had already spread to the bone, which usually marks the final stage of the disease. After 2 1/2 years, 16 of the patients were still alive, compared with a standard life expectancy at this stage of 7 to 11 months. Both companies are still several years away from seeking FDA approval.
Truly, It's Never Too Late to Quit
Lung-cancer patients who continue to smoke during chemotherapy are more likely to die within five years than those who don't. That may sound obvious, but many patients--90% of whom get the disease as a result of smoking--fail to kick the habit even during treatment. Dr. Greg Videtic of Dana-Farber Cancer Institute in Boston reported that of the 186 patients in his trial, 79 smoked during treatment, while 107 quit before chemo started. Both tolerated the therapy equally well, but two years after completion, 28% of nonsmokers were still alive, vs. 16% of smokers. Five years out, almost 9% of the quitters were still alive, vs. just 4% of the smokers. Ex-smokers have further cause for cheer: A preliminary study found that a derivative of Vitamin A called 9-cis retinoic acid can reverse some precancerous changes in the lungs of former smokers--a group that accounts for 50% of lung cancer cases in the U.S.
Stealth Death Rays and a Trojan-Horse Attack
One of the more exotic cancer treatments discussed in Orlando involved microscopic glass beads that shower beta rays onto malignant tumor cells. The approach, called TheraSphere, was created by MDS Nordion of Kanata, Ont., and tested against advanced, inoperable liver cancer.
In the test, doctors delivered millions of the glass beads impregnated with the isotope yttrium-90 into the liver via a catheter. The beads moved through the small blood vessels, where the radiation attacked the tumors. Of 36 patients treated, tumors shrank in 6 and stopped growing in an additional 18, said Dr. Brian Carr of the University of Pittsburgh School of Medicine. The FDA is now allowing doctors to use TheraSphere on patients who have no other options pending further study to determine its efficacy.
Telik in South San Francisco has a drug, TLK286, that is activated by the cancer cell's own defense system. Ingested by the patient, TLK286 molecules enter tumor cells and get chopped up by an enzyme that is present in many tumors. The chopping releases chemicals that attack the cancer cell, either killing it or making it more susceptible to chemotherapy. The drug stabilized the disease in half of 44 patients in the final stages of lung cancer.
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Copyright 2002 , by The McGraw-Hill Companies Inc. All rights reserved.
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