A Food and Drug Administration panel will vote Wednesday on
whether Amgen Inc.’ NPLATE drug to treat a rare blood clotting disorder provides
enough benefit to counteract the side effects associated with its use.
NPLATE is intended to treat Idiopathic Thrombocytopenic
Purpura (ITP), an autoimmune disorder characterized by very low levels of
plateles leading to uncontrolled bleeding. Plateles are involved in clotting
and are needed to stop bleeding, and NPLATE is designed to boost levels in a
different manner than other treatment.
Amgen’s drug would treat chronic forms of ITP. To support the
drug, Amgen submitted the results of two main clinical studies involving
patients with ITP who failed other treatments. The FDA said the studies showed
most patients treated with NPLATE had an improvement in blood-platelet levels. According
to the medical officer reviewing NPLATE, the product was a “safe and effective
alternative in raising the platelet count to levels where patients are no
longer considered to be at increased risk for serious bleeding.”
However, the FDA also noted that 14 of 204 patients treated
with NPLATE had dangerous blood clots. In addition, 8 percent of patients
taking NPLATE developed a resistance to the drug, while only 4 percent of
patients taking placebo showed the similar results. The FDA also expressed
concerns about abnormal marrow growth and malignant tumors seen in some
patients.
The FDA experts on Wednesday will decide whether the drug’s
benefits outweigh its risks, and whether it should be approved on a limited
basis, for example, for patients who have not responded to other drugs.
If approved, NPLATE’s label would warn of safety problems seen in company studies. In addition, the company would distribute additional guides on the risks to patients. Also, the company proposed studying irregular bone marrow growth and other adverse reactions in four follow-up studies.
ITP, which causes bruising and bleeding after minor injuries, affects about
200,000 people in the