Few drugs have stirred more excitement and hope than interferon, which was widely heralded in the late 1970s as a potential cure for cancer and viral diseases. Painstakingly extracted in minute amounts from living cells, the substance showed great promise in laboratory tests. And by the early 1980s, genetic engineering had made possible the production of interferon in quantities large enough to begin extensive testing in humans. But soon afterward disillusionment set in. Although interferon slowed the growth of some tumors, it had no effect on others, and it often produced disturbing flulike symptoms. Interferon, it seems, was not a magic bullet but, as Dr. Jules Harris, a cancer researcher at Chicago's Rush Medical College, puts it, "a complex group of drugs with complex side effects."
Undaunted, scientists continued to test the enigmatic substance. "People do not realize how slowly research progresses," says Dr. Jordan Gutterman, a leading interferon investigator at Houston's M.D. Anderson Hospital. "You don't go to the moon on the first rocket." At a meeting of the American Society of Clinical Oncology in Houston, it became clear that interferon has at the very least had a successful launch, and may be beginning to fulfill some of its early promise.
The big news in Houston was the remarkable success of alpha interferon (one of the three major types of the substance) in fighting an unusual cancer known as hairy-cell leukemia (because of the hairy appearance of the malignant cells). The disease is usually treated by removing the patient's spleen, but this seems to help in only about half the cases. For the other half, there was no viable treatment until interferon was tried. Two reports presented at the conference showed that interferon can be effective in up to 90% of hairy-cell patients, greatly reducing or completely reversing all signs of the disease. "We saw dramatic responses even in very advanced cases," says Dr. Harvey Golomb of the University of Chicago, who directed one study. Though interferon did produce flulike side effects, these generally disappeared after a few days of treatment. Says Dr. Jorge Quesada of M.D. Anderson, who led the other study: "We have patients who run five to ten miles a day while on interferon."
Although hairy-cell leukemia affects only 400 Americans a year, Golomb and Quesada point out that it is just one of several cancers that affect a class of white blood cells called B-cells; collectively these cancers strike 35,000 Americans a year. Says Golomb: "This may be a window into a family of disorders." Interferon has already proved useful in treating multiple myeloma, a B-cell-related cancer of the bone marrow that annually afflicts more than 8,000 Americans.
Interferon's performance against other forms of cancer has been inconsistent, but when it does work, the results can be dramatic. It has produced complete remissions (though not necessarily permanent cures) in advanced cases of kidney cancer; in malignant melanoma, a lethal form of skin cancer; and in Kaposi's sarcoma, a skin cancer that often strikes AIDS victims. In one study reported in Houston, just five out of 52 patients with advanced melanoma were successfully treated with interferon. But this handful was extraordinary: all signs of cancer disappeared within four months, even though the disease had spread to such organs as the liver and lungs.