Mon | Oct 15, 2018

In a milestone year, gene therapy finds a place in medicine

Published:Friday | December 29, 2017 | 12:00 AM
In this Monday, November 6, 2017 file photo, Brian Madeux sits with his girlfriend Marcie Humphrey while waiting to receive the first human gene editing therapy at the UCSF Benioff Children's Hospital in Oakland, California.

After decades of hope and high promise, this was the year scientists really showed they could doctor DNA to successfully treat diseases. Gene therapies to treat cancer, and even pull off the biblical-sounding feat of helping the blind to see, were approved by US regulators, establishing gene manipulation as a new mode of medicine.

Almost 20 years ago, a teen's death in a gene experiment put a chill on what had been a field full of outsized expectations. Now, a series of jaw-dropping successes have renewed hopes that some one-time fixes of DNA, the chemical code that governs life, might turn out to be cures.

"I am totally willing to use the 'C' word," said the National Institutes of Health's director, Dr Francis Collins.

Gene therapy aims to treat the root cause of a problem by deleting, adding, or altering DNA, rather than just treating symptoms that result from the genetic flaw.

The advent of gene editing a more precise and long-lasting way to do gene therapy may expand the number and types of diseases that can be treated. In November, California scientists tried editing a gene inside someone's body for the first time, using a tool called zinc finger nucleases for a man with a metabolic disease. It's like a cut-and-paste operation to place a new gene in a specific spot. Tests of another editing tool called CRISPR, to genetically alter human cells in the lab, may start next year.

"There are a few times in our lives when science astonishes us. This is one of those times," Dr Matthew Porteus, a Stanford University gene editing expert, told a Senate panel discussing this technology last month.

It's a common path for trail-blazing science success initially seems within reach, setbacks send researchers back to the lab, new understandings emerge over years, and studies ultimately reveal what is safe and effective.

... NOT ALL GOOD NEWS, THOUGH

The year 2017 started with no gene therapies sold in the US and only a couple elsewhere. Then the Food and Drug Administration (FDA) approved the first CAR-T cell therapies, which alter a patient's own blood cells to turn them into specialised cancer killers. They're only for certain types of leukaemia and lymphoma now, but more are in the works for other blood cancers.

Last week, the FDA approved Luxturna, the first gene therapy for an inherited disease, a form of blindness. People with it can't make a protein needed by the retina, tissue at the back of the eye that converts light into signals to the brain, enabling sight. The therapy injects a modified virus containing a corrective gene into the retina so the cells can make the protein.

Children who received the treatment told what it was like to gain vision.

"Oh yikes, colours. Colours are super fun," said 13-year-old Caroline Carper of Little Rock, Arkansas. "And the sunshine is blinding."

Gene therapies also showed some promise against a variety of diseases including haemophilia, a blood clotting problem; "bubble boy" disease, where a flawed immune system leaves patients vulnerable to fatal infections, and sickle cell disease, a serious and painful blood disorder common among black people.

It's not all good news, though. The therapies don't work for everyone. They're shockingly expensive. And no one knows how long some results will last, though scientists say the aim is a one-time repair that gets at the root cause.