Gene Therapy 101

Today,  a biotech start-up in Cambridge, Bluebird Bio Inc., has just gotten the FDA to designate their new drug therapy for beta-thalassemia, Lentiglobin, as a “breakthrough therapy”, which will speed up its development and regulatory review.

So what exactly is beta-thalassemia (let’s just call it BT)?  BT is a rare blood disorder that results in lower levels of hemoglobin, the protein in red blood cells that is responsible for transporting oxygen throughout the body. As a result, patients suffer from weakness and fatigue. What causes this disease is a mutation in the sequence of DNA that instructs the body on how to make hemoglobin. The body is still able to make hemoglobin, but the instructions aren’t correct, and so whatever it produces is ineffective.

What’s interesting about Bluebird’s approach to treating this disease is that is takes the road far less traveled. Gene Therapy Rd., to be exact. You’ve probably heard the term “gene therapy” thrown around before, but what is it exactly? The idea behind gene therapy is to replace a short stretch of DNA inside your body with a new DNA sequence. So what Bluebird is trying to do is to take stem cells out of patients suffering from BT, replace the mutated section of DNA within these cells with the corrected DNA, then reintroduce the cells back into the body.

Although gene therapy sounds fairly simple and straight-forward, it’s actually quite difficult to accomplish. There are many hurdles which must be overcome, among them ensuring that the DNA actually gets inserted into the patient’s DNA, making sure the DNA you introduce does not get destroyed by the body’s immune system before it reaches its destination, as well as making sure the DNA does not get inserted into a place it shouldn’t be (which could cause cancer to develop). Oh, and did I mention it’s also illegal in some countries?  See, some countries view gene therapy as too new to be safe, while others go as far as to say it’s unethical.

So its not really surprising that scientists haven’t gained much ground on gene therapy to date. That’s what makes the FDA’s interest in speeding up the development of this drug so exciting. It shows that we may finally be getting somewhere. It will be very interesting to see how this situation plays out in the future. I, for one, will be keeping a close watch!

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