Enlarge / Artist's conception of the CRISPR system in action, with the guide RNA (red) leading a protein to a specific site in the genomic DNA (blue) where it makes a cut. (credit: Stephen Dixon and Feng Zhang)

The UK has become the first country to approve a therapy based on Crispr gene editing, with the regulator authorising a treatment for sickle cell disease and beta thalassaemia.

The Medicines and Healthcare products Regulatory Agency has approved the therapy, called Casgevy, which was developed by Vertex Pharmaceuticals and Crispr Therapeutics. The drug could be used to replace bone marrow transplants.

The UK regulator has promised to focus on speeding the most innovative treatments to market after being given permission from next year to cut its workload by following other countries’ recommendations on approvals of other drugs. It had been struggling to keep up because of a lack of resources after the UK left the EU, where it had been a key part of the bloc’s regulatory agency.

Enlarge / Histological section of an artery suffering from atherosclerosis (credit: James Cavallini/Getty Images)

In a small initial test in people, researchers have shown that a single infusion of a novel gene-editing treatment can reduce cholesterol, the fatty substance that clogs and hardens arteries over time.

The experiment was carried out in 10 participants with an inherited condition that causes extremely high LDL, or “bad,” cholesterol levels, which can lead to heart attack at an early age. Despite being on cholesterol-lowering medications, the volunteers were already suffering from heart disease. They joined a trial in New Zealand and the United Kingdom run by Verve Therapeutics, a Cambridge, Massachusetts–based biotech company.

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Broad-spectrum antibiotics are akin to nuclear bombs, obliterating every prokaryote they meet. They're effective at eliminating pathogens, sure, but they're not so great for maintaining a healthy microbiome. Ideally, we need precision antimicrobials that can target only the harmful bacteria while ignoring the other species we need in our bodies, leaving them to thrive. Enter SNIPR BIOME , a Danish company founded to do just that. Its first drug—SNIPR001—is currently in clinical trials .

The drug is designed for people with cancers involving blood cells. The chemotherapy these patients need can cause immunosuppression along with increased intestinal permeability, so they can't fight off any infections they may get from bacteria that escape from their guts into their bloodstream. The mortality rate from such infections in these patients is around 15–20 percent. Many of the infections are caused by E. coli , and much of this E. coli is already resistant to fluoroquinolones, the antibiotics commonly used to treat these types of infections.

The team at SNIPR BIOME engineers bacteriophages, viruses that target bacteria, to make them hyper-selective. They started by screening 162 phages to find those that would infect a broad range of E. coli strains taken from people with bloodstream or urinary tract infections, as well as from the guts of healthy people. They settled on a set of eight different phages. They then engineered these phages to carry the genes that encode the CRISPR DNA-editing system, along with the RNAs needed to target editing to a number of essential genes in the E. coli genome. This approach has been shown to prevent the evolution of resistance.

Enlarge / The Nicobar pigeon, the dodo's closest living relative, is quite a bit smaller and capable of flight. (credit: Samuel Hambly / EyeEm )

Colossal is a company that got its start with a splashy announcement about plans to do something that many scientists consider impossible with current technology, all in the service of creating a product with no clear market potential: the woolly mammoth. Since that time, the company has settled into a potentially viable business model and set its sights on a species where the biology is far more favorable: the thylacine, a marsupial predator that went extinct in the early 1900s.

Today, the company is announcing a third de-extinction target and its return to the realm of awkward reproductive biology that will force the project to clear many technical hurdles: It hopes to bring back the dodo.

A shifting symbol

The dodo was a large (up to 1 meter tall), flightless bird that evolved on the island of Mauritius in the Indian Ocean. As European sailors reached the islands, it quickly became a source of food for them and the invasive species that accompanied them. It went extinct within a century of the first descriptions reaching Europe.

(credit: Lawrence Berkeley National Labs )

Last week, researchers published the results of a clinical trial that used CRISPR gene editing to create a large population of cancer-targeting immune cells. The trial was short, and the reprogrammed immune cells weren't especially effective against the cancer. But the technology, or something similar, is likely to be used in additional attempts to attack cancer and potentially treat a variety of diseases.

So, the trial provides a good opportunity to go through and explain what was done and why. But if you go back and re-read the first sentence, a lot was going on here, so there's a fair amount to explain.

Cancer and the immune system

Cancers and the immune system have a complicated relationship. The immune system apparently eliminates many cancers before they become problems—people who are on immunosuppressive drugs experience a higher incidence of cancer because this function is inhibited. And, even once tumors become established, there's often an immune response to the cancer. It's just that cancer cells evolve the ability to evade and/or tamp down the immune response, allowing them to keep growing despite the immune system's vigilance.

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Matthew Cobb is a zoologist and author whose background is in insect genetics and the history of science. Over the past decade or so, as CRISPR was discovered and applied to genetic remodeling, he started to get concerned—afraid, actually—about three potential applications of the technology. He’s in good company: Jennifer Doudna, who won the Nobel Prize in Chemistry in 2020 for discovering and harnessing CRISPR, is afraid of the same things . So he decided to delve into these topics, and As Gods: A Moral History of the Genetic Age is the result.

Summing up fears

The first of his worries is the notion of introducing heritable mutations into the human genome. He Jianqui did this to three human female embryos in China in 2018, so the three girls with the engineered mutations that they will pass on to their kids (if they’re allowed to have any) are about four now. Their identities are classified for their protection, but presumably their health is being monitored, and the poor girls have probably already been poked and prodded incessantly by every type of medical specialist there is.

The second is the use of gene drives . These allow a gene to copy itself from one chromosome in a pair to the other so it will be passed on to almost all offspring. If that gene causes infertility, the gene drive spells the extinction of the population that carries it. Gene drives have been proposed as a way to eradicate malaria-bearing mosquitoes, and they have been tested in the lab, but the technology has not been deployed in the wild yet.

Enlarge / A 3D illustration of the HIV virus. (credit: Westend61 / Getty )

In July, an HIV-positive man became the first volunteer in a clinical trial aimed at using Crispr gene editing to snip the AIDS-causing virus out of his cells. For an hour, he was hooked up to an IV bag that pumped the experimental treatment directly into his bloodstream. The one-time infusion is designed to carry the gene-editing tools to the man’s infected cells to clear the virus.

Later this month, the volunteer will stop taking the antiretroviral drugs he’s been on to keep the virus at undetectable levels. Then, investigators will wait 12 weeks to see if the virus rebounds. If not, they’ll consider the experiment a success. “What we’re trying to do is return the cell to a near-normal state,” says Daniel Dornbusch, CEO of Excision BioTherapeutics, the San Francisco-based biotech company that’s running the trial.

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Of all the species that humanity has wiped off the face of the Earth, the thylacine is possibly the most tragic loss. A wolf-sized marsupial sometimes called the Tasmanian tiger, the thylacine met its end in part because the government paid its citizens a bounty for every animal killed. That end came recently enough that we have photographs and film clips of the last thylacines ending their days in zoos. Late enough that in just a few decades, countries would start writing laws to prevent other species from seeing the same fate.

On Tuesday, a company called Colossal, which has already said it wants to bring the mammoth back, is announcing a partnership with an Australian lab that it says will de-extinct the thylacine with the goal of re-introducing it into the wild. A number of features of marsupial biology make this a more realistic goal than the mammoth, although there's still a lot of work to do before we even start the debate about whether reintroducing the species is a good idea.

To find out more about the company's plans for the thylacine, we had a conversation with Colossal's founder, Ben Lamm, and the head of the lab he's partnering with, Andrew Pask.