more questions about anemia drugs

[gdpawel]

EPO is a natural substance made by the kidney. It stimulates the bone marrow to make red blood cells (it is literally a "growth factor"). Healthy adults are usually at about 15 grams a deciliter. When normal people take it, their blood gets too "thick" and they die of heart attacks and strokes.

But it now looks as if increasing the hemoglobin level above 12 is very risky with pharmaceutical EPO. Pharmaceutical EPO makes sludgy blood.

The anemia drugs, which boosts patients' counts of hemoglobin (a protein that carries oxygen in the blood), raise the danger of heart attacks, strokes and death at "high" doses. The FDA has said there is "serious" cardiovascular risks for patients who took "higher than recommended" doses of these drugs. Also, patients who don't respond well to initial anemia therapy (hyporesponders) are exposed to the highest heart risks.

These anemia drugs are approved to treat patients whose weakness and fatigue is caused by chronic kidney disease or by the side effects of cancer chemotherapy. They stimulate production of oxygen-carrying red blood cells, which can boost patients' energy and strength. The issue is over the drugs' safety on how big a dose to use to boost concentrations of hemoglobin. The FDA-approved level is doses sufficient to increase hemoglobin to a maximum of 12 grams a deciliter.

Blood transfusions are generally needed when patients slip to less than 8 grams. The adage of some physicians was that if some improvement in hemoglobin was good, higher levels of hemoglobin would even be better. However, clinical trials have shown the drugs can reduce the need for blood transfusions and improve the quality of life when used within the "original" dosing range.

New studies have raised questions whether these drugs might be harming patients. Those study results suggest the drugs may make the cancer worse. One such study published in the New England Journal of Medicine found that patients treated aggressively with Procrit had a higher risk of heart problems or death than those treated less aggressively.

As reported in OncoLink, patients and clinicians must understand that no data exists to support claims of improvement in quality of life or fatigue. The manufacturers of these agents frequently used direct consumer marketing to promote these unsupported claims, a fact that concerns many patient advocacy groups.

And now there is emerging evidence that pharmaceutical EPO can feed the growth of tumors in cancer patients (it IS a "growth factor" afterall).

A “growth factor” is about twenty small proteins that attach to specific receptors on the surface of stem cells in bone marrow and promote differentiation and maturation of these cells into morphotic constituents of blood. And blood is a circulating tissue composed of fluid plasma and cells (red blood cells, white blood cells, platelets). Problems with blood composition or circulation can lead to downstream tissue (which is made up of cells) dysfunction. If pharmaceutical EPO stimulates the bone marrow to make red blood cells, it could feed the growth of tumors in cancer patients.

The problem is that few drugs work the way oncologists think and few of them take the time to think through what it is they are using them for. Take medical oncologists out of the retail pharmacy business and force them to be cancer "doctors" again!

Source: Cell Function Analysis