Cancer drug Sutent toxic for heart

20 December, 2007

The cancer drug Sutent, known generically as sunitinib and manufactured by Pfizer Incorporated, may cause cardiac toxicity.

In a study conducted in the United States, nearly half of 75 patients with rare gastrointestinal tumors who took the drug Sutent in a clinical trial developed high blood pressure, 11% had some cardiovascular event, 8% developed heart failure, two patients had heart attacks, and 47 per cent developed hypertension.

Analysis of clinical trial data by researchers at Children’s Hospital in Boston, the Dana-Farber Cancer Institute in Boston and Thomas Jefferson University in Philadelphia, suggested that patients taking Sutent – and especially those with heart risks – should be closely monitored.

In the study, published in the British medical journal The Lancet, Dr Ming Hui Chen, a cardiologist at the Children’s Hospital in Boston, wrote, “If a patient develops shortness of breath, fatigue, and swelling of the feet and hands, he should seek medical attention.”

The latest finding follows the discovery in 2006 that Gleevec, a pill manufactured by Novartis AG and which transformed treatment for leukemia patients, caused heart failure in 10 patients.

Both Sutent and Gleevec are smart drugs that are tyrosine kinase inhibitors, which target specific signaling molecules inside cancer cells. The study findings raise concern that these drugs may interfere with other healthy cells, such as heart cells.

Dr Ming Hui Chen, colleagues reviewed all heart events in 75 adults with gastrointestinal stromal tumors that had spread. They had been enrolled in a clinical trial in 2002-2004 intended to examine the safety of Sutent.

All patients in the study had developed resistance to Gleevec, or imatinib. All had normal heart pumping function before the study and none had a history of heart failure.

In the course of the study, 6 of the 75 patients suffered heart failure and 2 had heart attacks. Nearly half of the patients developed significant decreases in the heart’s ability to pump blood. In all, 35 out of 75 patients developed high blood pressure.

The researchers also studied the effects of Sutent in mice and rats and found evidence that heart cells were injured.

Future trials should include studies of the effects of Sutent on the heart and other systems, Dr Ming Hui Chen said, adding, “No drug is perfect and every drug has side effects. Patients must weigh the effectiveness of their treatments versus their risk for side effects.

Pfizer, in a statement, said that larger studies of the drug Sutent showed lower incidences of heart effects, including heart failure, high blood pressure and reduced pumping function.