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New studies have raised questions whether these drugs might actually be harming them. Those study results suggest the drugs may make the cancer worse.

Dr. Eric Winer, director of the breast oncology center at Dana-Farber Cancer Institute feels that these drugs are presumed to be entirely safe, given for supportive care and to improve quality of life, but not actually used to treat cancer. But the drugs may have been used in ways not approved on the labels.

A study published in the New England Journal of Medicine last November found that patients treated aggressively with Procrit had a higher risk of heart problems or death than those treated less aggressively.

Amgen, the maker of Aranesp, announced late January that in one of its clinical trials, patients were more likely to die than those getting a placebo. The trial was testing the drug in patients whose anemia was caused by the cancer itself, not by chemotherapy. While a Danish study in patients with head and neck cancer had to be stopped early because the cancer seemed to recur more in patients being treated with Aranesp.

In February, the Journal of Clinical Oncology published a paper describing a small Canadian trial in lung cancer patients had also been stopped early because those getting Eprex were dying sooner. While Roche suspended patient enrollment in a lung cancer trial comparing its Cera against Amgen's Aranesp because of greater than expected number of deaths in at least some of the arms of the trial.

It is not known why the drugs may cause these problems. It is known that raising hemoglobin levels too high increases the risk of blood clots. While most of these trials did aim to increase hemoglobin above the levels recommended in the drugs' labels, that was not the case with Amgen's own trial.

There is some evidence that clots were not the problem in the trials, but that Epo may spur tumor growth. Some studies suggest that certain tumor cells, such as those in head and neck cancer, have proteins on their surface that bind to Epo. When that happens, it sets off a cascade of reactions spurring growth.

Studies done by Dr. Jennifer R. Grandis, professor at the University of Pittsburgh, found enough biologic possibility that they can serve as a growth factor for the cancer cell.

Concerns about the safety of the drugs for cancer were first raised in 2003 by two studies that showed patients getting Epo had worse outcomes. Until then, these drugs had shown signs that they could improve the quality of life for cancer patients, even though their safety labeling has already been revised three times since 1997.

Whiz bang therapies often get a pass on toxicities because they are just so darn cool. The problem is that few drugs work the way we think and few physicians/scientists take the time to think through what it is they are using them for.

Source: TherapeuticsDaily