Gene Therapy for Hemophilia A: What to Expect in 2020

According to a story from, the field of gene therapy has gained increasing relevance throughout 2019, and 2020 will likely be a continuation of this trend. An area of gene therapy development that has gotten particularly hot recently is hemophilia A. There are currently three companies that are in the process of developing their own gene therapy for this rare blood disorder: BioMarin Pharmaceutical, Sangamo Therapeutics, and Spark Therapeutics. Their therapies are currently undergoing clinical evaluations and are poised to make possible advances in 2020.

About Hemophilia

Hemophilia is a genetic disorder which affects the ability of the blood to form clots, a process that is vital for stopping bleeding after a wound is sustained. The severity of symptoms can vary widely. The disorder is caused by a mutation found on the X chromosome. Symptoms include bleeding for a long time after an injury, risk of bleeding in the brain and joints, and easy bruising. Bleeding in the joints can cause permanent damage and brain bleeding can lead to headaches, decreased consciousness, and seizures. There are multiple types of hemophilia, with the most common types being type A and type B, which are distinguished by having deficiencies in different clotting factors. Treatment involves replacing the missing clotting factor. Drugs that thin the blood should be avoided. To learn more about hemophilia, click here.

BioMarin’s Valrox

So far, BioMarin’s investigational gene therapy valrox is in the most favorable position to be the first gene therapy approved for hemophilia A by the US Food and Drug Administration (FDA). While valrox is currently in phase 3 testing (with interim findings released this past May), the results in trials have been a little shaky. In earlier studies, the results indicated that patients who received the gene therapy eventually saw their factor levels drop over time, suggesting that the effect of the treatment wasn’t very long lasting. The drug’s impact also failed to hold up in the latest interim results (the company blamed differences in steroid use during the trials). Expect updates for this therapy in 2020.

Spark’s SPK-8001

For Spark, there hasn’t been any news on the progress of its gene therapy candidate since February. In the latest findings from a November 2019 phase 1/2 trial, the treatment, known as SPK-8001, appeared to be having a positive impact. The company appears to be preparing for the next stage of development; a lead-in study is expected to recruit 55 patients by July 2020.

Sangamo’s SB-525

Sangamo has had some of the most impressive findings so far; a phase 1/2 trial of its experimental gene therapy SB-525 saw patients gain normal levels of clotting factor just six weeks after receiving treatment. The latest update from July appeared to strengthen these initial results further. Development of the drug will be taken over by Pfizer this year, with dosing for a phase 3 trial expected in the first half of 2020.


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