Gene editing grabbed headlines recently after the discovery of CRISPR, a tool that allows scientists to cut out a particular, potentially faulty gene and paste another one in its place.
Dozens of other gene-editing technologies existed before CRISPR. French biotechnology company Cellectis was experimenting with one such technique, called TALENs.
Using the tool, Cellectis is developing treatments for cancers, and last year as part of a rare exception to a limited clinical trial, they treated an 11-month-old girl named Layla who had otherwise untreatable leukemia.
Business Insider sat down with Cellectis CEO Andre Choulika to learn more about TALENs and his plans toward getting more treatments like the one that helped Layla approved.
Cutting out faulty DNA
TALENs, the trademarked acronym that stands for “transcription activator-like effector nucleases” refers to proteins that can be used to make cuts in DNA. By programming the TALENs, researchers can use it to remove faulty DNA. Once the targeted DNA has been removed, it sends our natural DNA repair system into panic mode, hopefully repairing the gene.
This is the method Cellectis used to treat an infant identified only as Layla who was born in London with leukemia.
After Layla was born, her doctors tried to treat her using chemotherapy and a bone marrow transplant. When nothing worked, they reached out to Cellectis, who they knew had been working with TALENs, and asked if they’d try their experimental treatment on Layla using something called “compassionate use,” which would allow them to try it outside of a clinical trial setting.
The company said yes.
After extracting some of Layla’s blood and targeting some of her T-cells, special cells that play a critical role in our immune system, with the TALENs treatment, they were able to stimulate her immune system to attack her cancerous cells.
When she was tested a month later, all of Layla’s blood was tumour-free. At that point, “you could consider the patient in complete remission,” said Choulika.
Since June, Layla has reportedly stayed in remission.
Lots of gene-editing methods are heating up right now, including CRISPR and TALENs
Right now, three main gene-editing technologies are being explored for therapeutic use: CRISPR, TALENs, and zinc fingers. Of the three, zinc fingers was the first method to hit clinical trials. CRISPR, on the other hand, is new, advanced, and gaining traction fast.
With CRISPR, scientists choose which gene they want to modify, use a pair of “molecular scissors” to snip out the faulty one, and swap in a more desirable version. Both methods require using a bit of molecular material to guide the scissors to the correct gene so that the cell can repair the DNA. But while CRISPR uses a strand of easy-to-build RNA, or ribonucleic acid, to guide the scissors to the right location, TALENs uses an amino acid — a protein.
From a business point of view, one of the main differences between CRISPR and TALENs is that CRISPR is being used by a handful of companies and institutions (which are now facing some patent disputes). TALENs is the proprietary technology of Cellectis, so there are even fewer people using it through licenses.
“We comprehensively have an interesting IP and licence in this field,” Choulika said. “That’s what make people shy off TALEN, we have a pretty dominant position.”
Cellectis plans to start human trials in patients with acute myeloid leukemia sometime this year.
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