Patients with the bleeding disorder called immune thrombocytopenic purpura (ITP) harbor antibodies that sabotage production of the platelets responsible for proper blood clotting. ITP patients often feel fatigued and bruise so easily that they look battered. The most common treatment is a regimen of harsh steroids to suppress the rogue antibodies. Some patients have their spleens removed to relieve the aberrant immune reaction. These therapies leave patients susceptible to serious medical problems.
Scientists now report that ITP patients may soon be able to boost their platelet production with fewer side effects, thanks to two oral drugs that are nearing the end of clinical trials. Two other drugs in earlier testing also show promise, researchers reported in December 2006 at a meeting of the American Society of Hematology in Orlando, Fla.
James B. Bussel of the Weill Cornell Medical Center in New York City presented findings from two trials that together included 231 ITP patients. Roughly three-fourths of the participants getting a full dose of the new drug eltrombopag (Promacta) experienced a rise in platelets sufficient to restore healthy clotting, he says.
In another promising trial, a drug called AMG531 (SN: 1/1/05, p. 14: Available to subscribers at Drug counters severe platelet shortage) boosted platelet counts to healthy levels in 31 of 36 ITP patients, reports David J. Kuter of Massachusetts General Hospital in Boston.
In preliminary tests in healthy adults, two other drugs, known as AKR-501 and SB559448, increased platelet counts, other researchers reported.
“Patients say they know when their platelets are low because it feels like somebody pulled the plug on them,” Bussel says. If eltrombopag and AMG531 gain regulatory approval, they would improve an ITP patient’s quality of life and would ease “the realistic fear of bleeding,” he says.