A Cancer 'Smart Bomb'

Two summers ago, Douglas Jenson was so wiped out from battling Chronic Myelogenous Leukemia (CML) that he could do little more than sit by his window, watching the numbers on a thermometer rise and fall with the sun. Today, thanks to an experimental drug called STI571 (brand name: Glivec), Jenson, 67, is biking in Oregon and planning a trip to the Caribbean. "I feel wonderful," he says.

So do his doctors. STI571, a "smart bomb" drug that targets leukemia cells without harming healthy ones, first made headlines last year when researchers announced that white blood counts returned to normal in 31 out of 31 patients who had taken the pill. Last week scientists were back, reporting new data on just over 1,000 patients. In one trial, more than 90 percent of 532 people on the drug saw blood counts return to normal. And under microscopic examination, 28 per-cent showed no evidence of cancer left in their bone marrow. The drug even helped--though not as dramatically--some patients in the final, "blast" phase of the disease, when survival is measured in months. STI571 "has ignited the cancer-research field," says Dr. Brian Druker, an Oregon Health Sciences University researcher who developed the drug with manufacturer Novartis.

CML, diagnosed in 5,100 Americans every year, is triggered when two chromosomes swap fragments of genetic information. The mistake sends a flawed signal to white blood cells to replicate incessantly. Bone-marrow transplants can work extremely well, but they're applicable only for a minority of patients; otherwise, standard treatment is the injectable drug interferon. Many patients, however, can't tolerate the adverse effects, which include severe fatigue, weight loss and depression. The new pill works by deactivating the cancer cells' growth signal. Side effects--nausea, eye puffiness, muscle aches--have been relatively mild so far. There's still plenty to learn: will STI571 keep patients healthy for a prolonged period? Will undiscovered complications arise long-term?

New and ongoing trials will seek answers over the next few years. Researchers will also begin testing the drug in other cancers with similar molecular glitches: a rare intestinal cancer, a brain tumor called glioblastoma and small-cell lung cancer. Above all, scientists say STI571--which could be FDA-approved next year--is a milestone in cancer treatment. There will never be one cancer cure, but as researchers unravel the unique biological properties of different cancer cells, designer drugs like STI571 should begin to emerge one by one, says Dr. Michael Gordon of the Arizona Cancer Center. "It's a very exciting time to be an oncologist," he says. And a very hopeful time for patients.

A Cancer 'Smart Bomb' | News