What happened

After reporting intriguing interim data for its hemophilia A therapy and ahead of a planned update on its progress toward developing a zinc-finger nuclease gene-editing therapy for Hunter syndrome, shares of Sangamo Therapeutics (NASDAQ:SGMO) increased by 33.7% in August, according to S&P Global Market Intelligence.

So what

On Aug. 8, Sangamo Therapeutics announced that a hemophilia A patient receiving a high dose of its SB-525 gene therapy achieved therapeutic factor VIII activity. As a disease characterized by the inability to clot blood because of inadequate factor VIII levels, hemophilia A patients are at risk of life-threatening bleeding and painful joint damage. Currently, patients often take regular prophylactic doses of factor VIII to reduce their risks, however, those infusions are costly and they can negatively impact a patient's quality of life.

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Image source: Getty Images.

The potential to offer a gene therapy that's better than prophylaxis is important because hemophilia treatment is a billion dollar market. However, what may be even more interesting to investors is Sangamo's upcoming update on its zinc-finger nuclease (ZFN) gene-editing therapy, SB-913.

ZFN uses zinc-finger DNA-binding proteins (ZFP) to guide a cutting enzyme, known as Fok1, to a DNA sequence. The goal of ZFN is to correct genetic mutations responsible for disease by cutting away errant genetic code or replacing errant code with new code that allows genes to work correctly.

On Sept. 5, Sangamo Therapeutics, plans to update investors on SB-913 use in patients with MPS II, or Hunter syndrome, a lysosomal storage disorder caused by genetic mutations that inhibit a patient's ability to break down complex sugars. SB-913 attempts to address Hunter syndrome by inserting a functioning copy of the gene responsible for the protein necessary to break down these sugars in the liver.

Now what

Although Sangamo Therapeutics has been working on ZFN gene editing since the mid 1990s, the Hunter syndrome trial is its most advanced study of the technique. If SB-913 restores protein expression in patients, it would be a welcome advance that validates the company's platform.

However, there's still a lot of work to do to prove gene editing is effective and safe. DNA sequences often repeat throughout the body, so targeting DNA precisely to avoid off-target edits is a challenge. Even if SB-913's update is positive, additional studies will be necessary, and that could mean we're still years away from ZFN gene editing approaches winning FDA approval.

Similarly, the progress of its gene therapy for hemophilia A is encouraging, but investors will want to keep some enthusiasm in check. A number of companies, including Spark Therapeutics and BioMarin are developing gene therapies for hemophilia that could reach the market sooner than Sangamo's SB-525.

Overall, there are over 6,000 genetic diseases affecting over 300 million people globally, so investors will want to pay very close attention to Sangamo Therapeutics trials. If ZFN gene-editing pans out, it could represent a blockbuster opportunity someday.

 

Todd Campbell owns shares of BioMarin Pharmaceutical. His clients may have positions in the companies mentioned. The Motley Fool recommends BioMarin Pharmaceutical. The Motley Fool has a disclosure policy.