Nplate—Top Drug Innovation for 2008?

Fred Cohen, M.D., editor of the Pharma’s Cutting Edge blog, considers both Nplate and its fellow thrombopoeitin receptor Promacta to be among the top drug innovations for 2008. Why?

“(The TPO-agonist class) represents a potential major departure in the treatment of this uncommon, costly disease.”

Patients suffering from chronic ITP, or immune thrombocytopenic purpara, suffer platelet destruction and are unable to produce enough new platelets to compensate. Ecessive bleeding may result. The condition can often resolve itself, particularly in children, and is sometimes mild enough to require monitoring rather than treatment. Chronic sufferers, however, have a tougher row to hoe. Roughly 140,000 patients are currently being treated for chronic ITP in the United States and Europe.

The treatment goal is to maintain enough platelets to avoid bleeding events.

Results from an ongoing open-label extension study were recently reported at the 2008American Society of Hematology meeting in San Francisco, California. The long-term interim data shows that treatment with Nplate, which is approved for adults that have not responded to other forms of treatment such as corticosteroids, maintains platelet levels for up to four years.

The most commonly reported side-effects included headaches (34%) and confusion (30%), fatigue (30%), and nasopharyngitis (30%).

Follow-up on Nplate’s long-tem effectiveness and safety is continuing. At this point, only some 20 patients have been followed for more than three years.

Do you suffer from chronic ITP? How are you treating it? And if you’re being treated with Nplate, how is it working for you?

Nplate Can Cause Bone Marrow Fibrosis

In a clinical study of nplate involving 271 patients, four patients had to discontinue treatment due to the formation of reticulin fiber deposition within the bone marrow. Six more patients were found to have reticulin progression after having a bone marrow biopsy.

Reticulin fiber deposition is the early stage of bone marrow fibrosis, also known as myelofibrosis. This is a bone disorder where fibrous scar tissue replaces bone marrow, inhibiting the patient from developing new blood cells. As fewer blood cells are generated, less platelets as well as red and white blood cells are able to form (a condition called pancytopenia). Symptoms include bone pain, bruising and easy bleeding, fatigue, shortness of breath due to anemia, and abdominal fullness caused by an enlarged spleen.

Although all the patients in the controlled studies were able to stop treatment of Nplate before their reticulin progressed to bone marrow fibrosis, one patient in an extension study did develop fibrosis. As this happens, the patients may experience very low blood cell counts.

What do you think? Nplate is a new drug with potentially unknown long term effects. Please share any opinions or experiences you have concerning Nplate.