FDA approves gene-editing treatment for sickle cell disease

The U.S. Food and Drug Administration on Friday approved a landmark gene-editing treatment for sickle cell disease, a painful condition that affects approximately 100,000 people in the United States, predominantly people of color. The innovative therapy promises to repair the gene responsible for the disease.

The breakthrough offers a beacon of hope for Johnny Lubin, a 15-year-old from Connecticut who has lived with the debilitating effects of the disease. He inherited the sickle cell gene from both of his parents and has experienced severe pain and health complications since infancy. 

Red blood cells, which are normally donut-shaped, bend into inflexible sickle shapes, causing them to pile up inside blood vessels and prevent the normal delivery of oxygen in the body. Complications include bone deterioration, strokes and organ failure.

Doctors told Lubin he would not live past 40.

"I was starting to get a little bit scared. Like I actually did want to live past 40," he said.

For more than a decade, Lubin was in and out of the hospital. He said he would count how many times he had been in each hospital room and at one point he realized he had been in every room on the floor.  

Johnny's parents, Fabienne and J.R. Lubin, were desperate for a solution when they learned about a cutting-edge clinical trial involving gene editing, a process not requiring a donor.

First, stem cells were removed from Lubin's bone marrow and he was given chemotherapy to help wipe out the abnormal cells.

Then, in a laboratory, the editing technology called CRISPR was used to increase the amount of a protective form of hemoglobin, a protein that picks up oxygen from lungs and delivers it throughout the body — that protective form usually diminishes after birth. The cells were then infused back into Lubin's bloodstream.

Dr. Monica Bhatia, who is Johnny's doctor and the chief of pediatric stem cell transplantation at NewYork-Presbyterian/Columbia University Irving Medical Center, said by editing the cell, you're reprogramming cells to produce fetal hemoglobin.

"It's been widely known that fetal hemoglobin is somewhat protective and those who have higher levels of fetal hemoglobin tend to have less severe symptoms of sickle cell disease," she said.

"You're changing somebody's DNA. So obviously you wanna make sure that the corrections you're making are, are the ones you want," said Bhatia.

After a challenging five weeks in the hospital and a six-month absence from school, Lubin has drastically improved health and prospects for a longer life.

"I thought that was pretty cool how I have like new cells and I honestly hoped, you know, I could get, you know, some super powers from it, you know, maybe become a superhero, you know, like genetically engineered," Lubin said. 

The treatment, called Casgevy, was developed by the Boston-based Vertex Pharmaceuticals and CRISPR Therapeutics.

Patients will have to be followed long-term before the experts call this a cure. Gene editing is expected to cost several million dollars per patient and may not be appropriate for everyone who has sickle cell disease. It would also not prevent the gene from being passed down to future generations.

Jon LaPook

Dr. Jonathan LaPook is the chief medical correspondent for CBS News.

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