MEDICINE

Curing a rare cancer with a wonder drug

PAT OHLENDORF June 16 1986
MEDICINE

Curing a rare cancer with a wonder drug

PAT OHLENDORF June 16 1986

Curing a rare cancer with a wonder drug

MEDICINE

In 1981 Sven Siems of Toronto underwent a routine physical checkup and learned that he was suffering from hairy-cell leukemia—an invariably fatal blood cancer. Despite treatment, which included the removal of his spleen and monthly blood transfusions, Siems swiftly discovered that he could not even walk upstairs without difficulty. But in 1983 his physician referred him to a Canada-wide clinical trial to combat the cancer with interferon—a protein which the body produces naturally in response to viral infection. The 20-month treatment program has so far been successful for Siems: the 55-yearold industrial manager no longer needs injections of the drug three times a week, and his disease has been in remission since November.

Up to 90 per cent of the 37 Canadians—and 150 U.S. victims—who participated in trials have survived for more than two years. And 75 per cent reported that the disease was in remission. As a result, the U.S. government approved interferon last week as a prescription drug against hairy-cell leukemia—a step taken by Ottawa a month earlier.

For victims of that particular type of leukemia—named because of the hair-like projections that the cancerous blood cells display—the dramatic results of the clinical trials have created a new optimism. The disease is rare, affecting fewer than 200 Canadians and 3,000 Americans. And until the recent breakthrough most patients died about five years after contracting the disease, which cripples the body’s ability to produce blood cells.

Interferon itself was first discovered in London 29 years ago, and during the late 1970s some experts considered it to be the long-sought cure for cancer. That promise failed to materialize when the drug performed poorly against lung, liver, pancreas and prostate cancer. But advances in genesplicing techniques have made it easier to produce larger quantities of the substance-enabling scientists to expand trials of its effectiveness. And Hoffmann-La Roche Inc. and ScheringPlough Corp., two giant New Jerseybased pharmaceutical firms which have separately developed almost iden-

tical forms of interferon, are seeking a wider market beyond the tiny population of hairy-cell leukemia victims.

Schering is already selling its product, known as Intron A, in the Republic of Ireland and the Philippines. Both countries have approved Intron A not only for the treatment of hairy-cell leukemia but also for Kaposi’s sarcoma, a severe skin cancer linked with

Acquired Immune Deficiency Syndrome (AIDS), and some types of bone and skin cancer. Although interferon has not produced as dramatic results against those cancers, Schering’s studies show that 50 per cent of Kaposi patients and up to 20 per cent of those bone and skin cancer patients treated have responded well. The company is also testing interferon on kidney cancer and two kinds of bladder cancer. Declared Dr. Daniel Bergsagel, director of medicine at Toronto’s Princess Margaret Hospital and the specialist who treated Siems: “It is possible that interferon could act as an effector— that is, it could make other treatment like chemotherapy more effective.”

Most medical scientists and doctors say that there will never be a single cure for all cancers. But according to Dr. John Chiz, director of scientific affairs for Montreal-based Schering Canada Inc., interferon is entering “a new stage of realism—we realize its limitations, but we believe it will find

a valuable place in the treatment of cancer and viruses.” In support of that goal, researchers are attempting to discover if interferon works by stimulating the immune system or by killing cancer cells directly.

They will also try to determine which of the three main types of interferons, perhaps even in combination, will be most effective against different

forms of the disease. Cross-Canada marathoner Terry Fox received interferon in an unsuccessful attempt to halt the cancer which spread to his lungs and killed him in 1981. But at that time interferon was more expensive and not as pure: treatments often contained only two-per-cent pure interferon and cost $150 per injection. By contrast, Schering’s Intron A costs about $30 per injection and is 98-percent pure.

Yet Sven Siems says that the substance should not be considered a miracle drug. He has survived a personal battle with cancer but he acknowledges that an element of luck was involved in the struggle. Said Siems: “The miracle in this for me is that somebody tried it with hairy-cell leukemia and it just happened to work.” But the encouraging research results indicate that it may be a powerful weapon against many forms of the disease.

PAT OHLENDORF