Dec. 10 (Bloomberg) -- Drugs from Bristol-Myers Squibb Co. and Novartis AG helped leukemia patients remain free of cancer for a year in separate clinical trials, igniting a race to beat one of the world's most effective cancer treatments.

Bristol-Myers' Sprycel eliminated any trace of disease among all 24 patients with chronic myelogenous leukemia for one year, according to research presented today at the American Society of Hematology meeting in Atlanta. Novartis's Tasigna achieved the same goal for all 11 patients in a separate trial.

Both drugs are approved for the 10 to 15 percent of CML patients who relapse or can't take Novartis's Gleevec, the standard treatment proven to boost survival of patients with leukemia, a blood disease. The findings prompted New York-based Bristol-Myers and Switzerland's Novartis to start trials in September to compare their newer drugs to Gleevec, targeting a market worth $4 billion a year in peak sales, Novartis said.

``These are early results, but certainly encouraging so far in both cases,'' said Jorge Cortes, a leukemia specialist at M.D. Anderson Cancer Center in Houston, and lead author of both studies, in a statement.

Novartis, based in Basel, Switzerland, was unchanged at 64.80 Swiss francs in Zurich trading. Bristol-Myers rose 8 cents to $29.31 at 4:01 p.m. in New York Stock Exchange composite trading.

No Direct Comparison

The studies didn't directly compare the new treatments to Gleevec. Earlier trials suggested that after one year, Gleevec could eliminate leukemia in the blood for 65 percent of patients at the recommended dose, and 86 percent at a higher dose.

Novartis' Gleevec was first approved by the U.S. Food and Drug Administration in May 2001, after less than three months of review. The Oregon Health & Science University, where they did the pioneering work on Gleevec, said at the time that it was the fastest-ever approval in the agency's history.

The medicine was hailed as a breakthrough for efforts to develop drugs built on better knowledge of the molecular root causes of cancer. Drugs like Gleevec represent ``the wave of the future,'' said former U.S. Secretary of Health and Human Services Tommy Thompson, when it was first cleared for sale.

Gleevec generated $2.5 billion in sales in 2006, its fifth year on the market, Novartis said in its annual report. The treatment comprised about 6.7 percent of Novartis' $37 billion in revenue.

CML is a form of leukemia caused by uncontrolled growth of white blood cells in the bone marrow. About 4,750 patients, mostly adults, are diagnosed with the cancer each year in the U.S., according to the American Cancer Society.

Gleevec Success

Before Gleevec, chemotherapy or immune-suppressing medications were used against the disease. The drug has dramatically increased a CML patient's chance of beating the cancer, with studies showing that it boosts the five-year survival rate of leukemia patients from 50 percent to 90 percent.

``No other cancer drug before Gleevec achieved what it has, so to beat it is quite ambitious,'' David Epstein, chief executive officer of Novartis's oncology division in Florham Park, New Jersey, said in an interview.

Bristol-Myers and Novartis's new medicines have significant side effects. Tasigna, designed to be 30 times more potent than Gleevec, caused serious depletion of infection-fighting white blood cells for 7 percent of patients. The drug's prescribing information also carries a warning that it can cause a condition that leads to an abnormal heart rhythm that can be fatal.

Fluid Buildup

Sprycel has been known to cause fluid buildup in the lungs for about 10 percent of patients, said Claude Nicaise, vice president of global clinical development for Bristol-Myers, in an interview. The drug appeared more tolerable in the M.D. Anderson study when given once a day instead of twice a day, he said.

Officials at both companies say they hope to finish the comparison trials and submit results to regulators in 2010.

``We are very comfortable we will be able to demonstrate superiority,'' said Nicaise, of Bristol-Myers.

Sensitive diagnostic tests suggest Tasigna is outperforming Sprycel, said Norvartis's Epstein. It will be difficult to top Gleevec, which has a long record of extending lives, he said.

To contact the reporter on this story: Luke Timmerman in San Francisco at ltimmerman@bloomberg.net

Last Updated: December 10, 2007 16:15 EST