According to a press release from American biotechnology company Fortress Biotech, the American Food and Drug Administration (FDA) recently awarded Regenerative Medicine Advanced Therapy designation to the experimental gene therapy MB-107.The drug is intended to treat X-linked severe combined immunodeficiency (SCID).
About X-linked Severe Combined Immunodeficiency
X-linked SCID is a highly rare condition characterized by severely deficient immune activity caused by a low lymphocyte count. Lymphocytes are a kind of white blood cell, and play an important part in dictating immune response. In healthy individuals, lymphocytes make up anywhere between twenty and 40% of all white blood cells.
Patients with X-linked SCID are liable to frequent and persistent bacterial, viral, and fungal infection.Without treatment, most affected do not live beyond infancy. In fact, without reinforcement of the immune system through gene therapy or bone marrow transplant, X-linked SCID is almost always fatal within the first two years of life.
The condition is caused by mutations to the gene IL2RG. In healthy individuals, this gene codes for the production of a protein called the common gamma chain. This protein plays an important role in normal immune system function, and is required for the production and maturation of nascent lymphocytes. Mutations to IL2RG lead to irregular development of lymphocytes, leaving the immune system dangerously under-equipped to properly function.
Because men receive only one X-chromosome from their parents, X-linked SCID and other conditions are much more common in males than in females.
About MB-107 and Regenerative Medicine Advanced Therapy
MB-107 is a lentiviral gene therapy. Like similar gene therapy processes, lentiviral gene therapy uses a modified inert lentivirus to deliver modified genetic material to patients with conditions caused by genetic mutations. Viruses are exceptionally good at slipping past the body’s defenses and injecting their DNA into that of a host cell — especially if the virus has been specifically engineered to do so in a laboratory. Modified genetic information planted in the virus then replicates inside host cells, eventually creating a functional immune system (hopefully).
Regenerative Medicine Advanced Therapy (RMAT) designation is one of many research designations offered by the FDA that are designed to either directly benefit or otherwise help researchers who develop treatments for serious diseases with inadequate treatment options. RMAT is specifically offered to researchers who develop regenerative medicines (cell therapy, marrow transplant, skin graft, etc.).
The RMAT designation entitles Mustang Bio (and parent Fortress Biotech) to FDA assistance in the form of trial management assistance and an expedited review process. The designation was awarded following an impressive phase 1/2 clinical study of the drug in infants earlier this year.
The drug development process for MB-107, though still a long one, could be significantly shortened by this designation.
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