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A twice-a-year injection that reduces bad cholesterol to protect the heart is to be pioneered by the NHS in England.

Already, millions of people take daily statin pills to cut their cholesterol.

But later this year, a "ground-breaking" large-scale clinical trial will offer NHS patients a new form of medicine, gene silencing, in an injection called inclisiran.

Health Secretary Matt Hancock said the initiative could save 30,000 lives during the next decade.

Why is cholesterol a problem?

Bad cholesterol (officially called non-high-density lipoproteins cholesterol) can build up inside the walls of blood vessels, making them narrower and increasing the risk of having a heart attack or stroke.

A bloodstream-tussle takes place between "bad" cholesterol which dumps fatty material in the arteries and good cholesterol taking it away.

What is the new drug?

It is called inclisiran and it is given by injection every six months.

It is part of a new form of medicine called gene-silencing.

Inclisiran does not modify our DNA, but it controls the instructions the body gets.

It does this by "silencing" the PCSK9 gene, which results in the liver absorbing more "bad" cholesterol from the blood and breaking it down.

The first gene-silencing medicine was approved for NHS use last year for a relatively rare disease, hereditary trans thyretin-mediated amyloidosis.

How big an impact could inclisiran have?

Trials presented at the European Society of Cardiology last year showed it could cut bad cholesterol levels in half within weeks.

Prof Kausik Ray, who led those trials, from Imperial College London, says this gives it "enormous" potential.

And the Department of Health and Social Care says it would prevent 55,000 heart attacks and strokes each year for every 300,000 patients treated.

Who will be offered the drug?

The drug is not yet a licensed medicine, but a deal between the NHS and the pharmaceutical company means patients will be access the drug later this year as part of a large-scale clinical trial.

NHS patients who have not had a heart attack or stroke but are at high risk of having one will be invited to take part.

About 40,000 people might be eligible.

Inclisiran will also be assessed for more routine use next year based on evidence from previous trials.

At the moment - because of the way decisions on health are devolved within the UK - the announcement applies only in England.

What is special about this trial?

The NHS has described this collaboration between the health service, drug company Novartis and researchers as "ground-breaking".

"It is certainly innovative, exciting and a step-change in the way we do clinical trials," Prof Martin Landray, who will lead the trial from the University of Oxford.

Inclisiran is a drug people could potentially take for decades so it is essential to be able to monitor the long-term risks and benefits of taking the drugs.

Will this replace regular statins?

Statins are a cornerstone of heart medicine that are taken by millions of people in the UK.

They work by lowering levels of bad cholesterol.

However, some patients have such high cholesterol that it is still at dangerous levels even with statins.

And studies have shown they do not work well enough in roughly half of patients.

There are many types of statin and some patients could be on the wrong one. Or patients may be forgetting to take their daily pill.

It is some of these issues that having two injections a year might help with.

What do the experts say?

Prof Naveed Sattar, from the University of Glasgow, said: "Doctors are excited by inclisiran and the potential to 'vaccinate' against high cholesterol in some patients.

"However, many would also like to see longer term safety data from ongoing trials and to be told the cost of this new drug before they consider implications for care."

Prof Jacob George, from the University of Dundee, said: "Whilst inclisiran has not yet been assessed by the European Medicines Agency or the FDA [US Food and Drug Administration], giving patients access to these innovative new medications within the safety confines of a large-scale trial is welcome news."

And Dr Riyaz Patel, clinical lead for cardiovascular disease prevention at Barts Health NHS Trust, said: "This as a really exciting announcement that changes the way we bring new medicines to patients earlier and [will] also propel the NHS and the UK as a world leader in this sort of clinical research.

"It is certainly a welcome step forwards to get exciting new drugs to patients quickly and safely."