New Study Suggests a ‘Clinical Cure’ May be Around the Corner for Hemophilia B.

Hemophilia is an inherited genetic disorder that prevents blood from clotting. Individuals with the disorder are prone to excessive and sometimes spontaneous bleeding that can lead to death or disability.

Chinese researchers from the Hematology and Blood Diseases Hospital at the Chinese Academy of Medical Sciences, in a joint research project with the East China University of Science and Technology and gene therapy company Belief BioMed, believe they have discovered a treatment that will allow patients suffering from hemophilia B to live normal lives.

The researchers designed a gene therapy drug called BBM-H901. The study, published last week in The Lancet Haematology journal, focused on 10 patients with moderate to severe hemophilia, and after over a year of study, found that all but one patient did not suffer any bleeding episodes. They also did not suffer severe side effects to the drug, implying that the treatment is safe for at least a year after infusion.

In 10 of the patients, the clotting factor increased from less than 2% to an average of 36.9%. Clotting for normal adults is between 50 - 120%, but individuals who have blood clotting levels between 20% and 40% rarely have excessive bleeding episodes.

In the study, the median excessive bleeding episodes in the patients decreased from 12 times annually to zero.

The drug does not eliminate the gene defect in patients, so it cannot be called a true cure. However, if it proves effective in further studies, it could be what is called a clinical cure, meaning patients can live a normal life as if they were cured.

“In our long term follow up, only one patient received replacement therapy due to aggravation of a previous haematoma. No other patients had excess bleeding, which greatly reduced their pain,” the researchers said in a statement.

While hemophilia B and hemophilia A are very similar in how they manifest, they are caused by two different genes, so BBM-H901 will likely not be effective for hemophilia A patients. Hemophilia A is the more common of the two, affecting 1 in 5,000 to 10,000 males, while the B variant only affects 1 in 25,000 to 30,000 males.

The research paper does not indicate if similar techniques could be used to develop a treatment for hemophilia A.