SAN FRANCISCO (TheStreet) -- Acceleron Pharma (XLRN) - Get Report scored some premium visibility at the American Society of Hematology (ASH) annual meeting. Two of the company's experimental drugs -- both designed to boost red blood cell production in patients with anemia caused by rare blood disorders -- were featured during a media session Sunday morning.

Celgene (CELG) - Get Report has worldwide clinical development and marketing rights to the two Acceleron drugs, known as luspatercept and sotatercept. Both drugs work in similar ways and are potentially competitive against each other, so ultimately Celgene may choose to advance one and kill the other off. Right now, Acceleron is conducting mid-stage clinical trials of both drugs, including studies enrolling patients with beta-thalassemia and myelodysplastic syndrome.

In one study, 30 patients with beta-thalassemia were treated with escalating doses of luspatercept, given as an injection every three weeks. The beta-thalassemia patients were divided into two groups depending on whether or not they required regular blood transfusions to manage their disease.

Among 23 patients not dependent on chronic blood transfusions, higher doses of luspatercept led to increases in hemoglobin levels in half the patients. Lower doses of luspatercept were not effective.

The study also enrolled seven beta-thalassemia patients dependent on blood transfusions. Six of these patients were treated with the higher doses of luspatercept -- all of them were able to reduce their transfusion burden by at least 20%.

Beta-thalassemia is a disease caused by a missing or defective gene that prevents oxygen-carrying hemoglobin from functioning properly. Beta-thalassemia patients suffer from chronic anemia which can require regular and lifelong blood transfusions.

In a separate phase II study, patients with myelodysplastic syndrome were treated with escalating doses of luspatercept injections, leading to higher hemoglobin levels and enabling some patients to become transfusion independent. Full results from this luspatercept study are being presented Monday at the ASH annual meeting.

Myelodysplastic syndrome (MDS) is a cancer-like disease in which the bone marrow is incapable of producing sufficient and healthy blood cells.

A mid-stage study of sotatercept in MDS patients was also presented Sunday, showing increases in hemoglobin production.

Both of the Acceleron drugs are designed to increase the production and maturation of late-stage red blood cells. This mechanism is different from erythropoietin-stimulating agents (ESAs) like Amgen's (AMGN) - Get Report Epogen, which works on early-stage red blood cells.

Patients with rare blood diseases like MDS and beta-thalassemia are treated with ESAs to boost their red blood cells, but the drugs can become less effective over time or never work at all. Acceleron believes luspatercept or sotatercept could prove to be an effective treatment for anemia because the drugs work differently than ESAs.

Celgene's blockbuster blood cancer drug Revlimid is approved as a treatment for myelodysplastic syndrome, so the Acceleron drugs are potentially complementary.

One wrinkle worth watching is the potential development of a curative gene therapy for beta thalassemia from Bluebird Bio (BLUE) - Get Report which may obviate the need for Acceleron's new anemia therapies. Updated results from a study of Bluebird's beta-thalassemia study will be presented Monday at the ASH annual meeting.

Adam Feuerstein writes regularly for TheStreet. In keeping with company editorial policy, he doesn't own or short individual stocks, although he owns stock in TheStreet. He also doesn't invest in hedge funds or other private investment partnerships. Feuerstein appreciates your feedback;

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