THURSDAY, Dec. 13 (HealthDay News) -- The new and powerful cancer drug sunitinib (Sutent), which fights stomach tumors, can also create heart problems for some patients, a new study finds.

All patients taking sunitinib, but especially those who have risks for heart disease, need careful monitoring and treatment for high blood pressure and other signs of heart problems, researchers say.

"All drugs have risks and benefits," noted lead researcher Dr. Ming Hui Chen, an assistant professor of medicine at Harvard Medical School and a cardiologist at Children's Hospital Boston. "This drug is lifesaving for people with metastatic, gastrointestinal stromal tumors," she added.

But it is important for both doctors and patients to be aware that sunitinib can have cardiac effects, Chen noted.

"The people at greatest risk are the people who have a history of coronary artery disease," Chen said. "Aggressive control of blood pressure in these patients is very important."

In a statement released Thursday, sunitinib's maker, Pfizer Inc., agreed that these heart risks do exist. However, they added that the cardiovascular events "were medically manageable in most patients and underscore the importance of having a collaborative team of healthcare professionals working together to appropriately manage patients, who have limited available options" in treating their cancer.

The new, collaborative study was supported by Children's Hospital Boston; the Dana-Farber Cancer Institute; Thomas Jefferson University; the U.S. National Heart, Lung, and Blood Institute; the Finnish Heart Foundation; and the American Heart Association.

Sunitinib is one of a family of new and powerful anti-cancer drugs called tyrosine-kinase inhibitors, which target key molecular pathways thought to encourage tumor growth. Other drugs in this family include imatinib, better known as Gleevec, and dasatinib (Sprycel).

In the study, which is published in the Dec. 15 issue of The Lancet, Chen's team looked at 75 patients with metastatic, gastrointestinal stromal tumors that had not responded to standard therapy with Gleevec. The patients had taken part in a phase I/II trial studying the efficacy of sunitinib.

The researchers looked back at the medical records of these patients, noting those who died from heart disease or had suffered heart attacks or congestive heart failure. They also looked at the effect of sunitinib on the heart's ability to pump blood and on blood pressure.

Chen's group found that eight patients given repeated cycles of sunitinib had cardiovascular events. Two had heart attacks, and six had heart failure. Of 36 patients given the approved dose of sunitinib, 10 had a 10 percent or more reduction in the ability of their heart to pump blood, and seven had a 15 percent or more reduction in heart function.

In addition, sunitinib was associated with increases in blood pressure, with a total of 35 (47 percent) of the patients developing hypertension. However, these effects were not permanent: When sunitinib treatment was stopped and patients began therapy to ease heart problems, levels of heart failure and heart functioning improved, the researchers found.

"Most of the patients who had heart problems were able to resume taking sunitinib with either a modification in their dose or initiation of heart failure medication," Chen said.

In addition, in experiments with mice and rat heart cells, Chen's team found that sunitinib triggered heart cells damage and death.

However, in their statement, Pfizer noted that, "Lower incidences of cardiovascular effects have been observed in subsequent randomized Phase 3 prospective Sutent studies in both renal cell carcinoma and gastrointestinal stromal tumor[s]." That includes a lower incidence of events such as congestive heart failure, impaired heart function, and high blood pressure that were noted in Chen's retrospective analysis, the company said.

Chen stressed that patients taking sunitinib who develop shortness of breath and fatigue and swelling of the arms or legs should be checked for heart problems. "These symptoms can be ascribed to cancer, but since this drug may have a cardiovascular effect, these may be signs of heart problems," she said.

One expert said the findings must be approached with caution.

"The findings are intriguing, but one has to be careful about generalizing them," said Dr. James Brugarolas, an assistant professor in the division of oncology at Simmons Comprehensive Cancer Center at the University of Texas Southwestern Medical Center at Dallas. "It's a small group of patients, many of whom were taking other drugs that can have cardiac effects," he said.

However, patients who have coronary artery disease who are going to be given sunitinib should be very carefully monitored for the development of heart failure, Brugarolas said. "There should be a proactive attitude on the part of the physician to manage hypertension," he added.

Brugarolas also noted that sunitinib has been shown to slow the progression of gastrointestinal stromal tumors but not to extend patients' overall survival. "These side effects may be affecting survival," he said. "If survival is compromised by adverse effects of the drug, then it may not be beneficial to patients."

More information

For more on sunitinib, visit the U.S. National Library of Medicine.

SOURCES: Ming Hui Chen, M.D., assistant professor, medicine, Harvard Medical School, and department of cardiology, Children's Hospital Boston; James Brugarolas, M.D., Ph.D., assistant professor, division of oncology, Simmons Comprehensive Cancer Center, University of Texas Southwestern Medical Center at Dallas; Dec. 15, 2007, The Lancet; Dec. 13, 2007, statement, Pfizer Inc.

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