The company said it would study the treatment SCIg -- a 20-percent formulation of subcutaneous immunoglobulin derived from blood plasma -- in an open-label, registration trial involving 54 patients at 13 U.S. centers.

The primary goal of the company's IgPro20 study is to assess the rate of bacterial infections -- including pneumonia, bacteremia and septicemia, osteomyelitis/septic arthritis, meningitis and visceral abscess -- in male and female patients with PI between the ages of 2 and 75 who need immune replacement therapy, CSL Behring said.

PI is a rare, genetic condition that compromises the immune system, leaving patients vulnerable to potentially fatal bacterial infections. About 70 percent of the estimated 50,000 people in the United States who have the condition need immune replacement therapy, the company said.