How gene therapy eyedrops helped restore a boy's eyesight

Antonio Vento Carvajal, a 14-year-old boy from Cuba, was born with dystrophic epidermolysis bullosa, a rare genetic condition that affects around 3,000 people worldwide. The condition is caused by mutations in a gene that helps produce the collagen 7 protein, which keeps skin and the cornea together. 

The condition caused blisters all over Carvajal's body and on his eyes. Because of heavy scarring on his eyes, he was legally blind for most of his life.

In 2012, Carvajal and his family traveled to the United States on a special visa that allowed him to get treatment for his condition. After joining a clinical trial for a topical gene therapy treatment, his skin improved. The treatment, which is called Vyjuvek, uses an inactivated herpes simplex virus to deliver working copies of the gene that produces collagen 7.

To treat his eyesight, Carvajal received surgeries to remove scar tissues from his eyes, but the scarring grew back, and his vision continued to worsen. Eventually, his sight deteriorated so much that he did not feel safe walking around.

It wasn't until Carvajal told his doctor Alfonso Sabater, director of the Corneal Innovation Lab at the University of Miami Health System's Bascom Palmer Eye Institute, about the topical gene therapy treatment he received that another potential solution emerged. After hearing about the topical treatment, Sabater contacted Krystal Biotech, Vyjuvek's manufacturer, to see if the drug could be reformulated to treat Carvajal's eyes.

The company agreed with Sabater's proposal and began developing a liquid version of the drug that could be used as eyedrops. After two years, Carvajal's team received "compassionate use" approval from FDA, as well as permission from university and hospital review boards, to test the treatment on his eyes.

Last August, Carvajal had surgery on his right eye to remove scarring before starting to use the eye drops. Since then, he has not seen any scarring return, and his vision has improved each month, with doctors recently measuring it at a near-perfect 20/25.

Carvajal also began treatment on his left eye this year, and it is steadily improving. His vision in his left eye currently measures at around 20/50, which Sabater said is "pretty good vision."

Because Vyjuvek is not a one-time treatment like many other gene therapies, Carvajal is still using the topical version for his skin and receives the eye drops once a month at the eye institute.

What the future holds for this treatment

According to Sabater, the two-year effort to get government and hospital approval for the treatment "was worth it. Just for Antonio, it was worth it … but also because it opens the space to treat other patients in the future."

In the future, Sabater said gene therapy eyedrops could be used to treat other diseases if the gene carried by the virus in the treatment was changed. For example, a treatment containing a different gene could be used to treat Fuchs' dystrophy, a genetic condition that affects 18 million Americans and accounts for around half of the corneal transplants in the United States.

The possibility of treating more conditions with this method is "exciting," said Aimee Payne, a dermatology professor at the University of Pennsylvania. This approach "delivers gene therapy that really addresses the root cause of disease." (Ungar/Frisaro, Associated Press, 7/24)

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