New kind of gene "silencing" drug works in monkeys

By Ben Hirschler

LONDON (Reuters) - A new class of drug that fine tunes the action of genes has been shown to cut cholesterol in monkeys and may fight a range of ills, including hepatitis C and perhaps cancer, scientists said on Wednesday.

The compound, from Danish biotech firm Santaris Pharma, works by blocking or "silencing" microRNAs -- tiny strands of RNA, or ribonucleic acid, that help turn genes into proteins.

The ground-breaking study is the first demonstration of microRNA silencing in primates and an early endorsement of the technique. Phase I safety trials are now planned in humans.

Unlike other drugs in the hotly pursued RNA interference field, the new designer molecule, known as Locked Nucleic Acid (LNA), can be given as a simple injection rather than having to be delivered direct to affected tissue.

"We think LNA is a one-stop shop for silencing," Santaris Chief Executive Keith McCullagh told reporters.

Scientists from Santaris and the University of Copenhagen lowered total cholesterol in African green monkeys by up to 30 percent, without ill effects, by targeting a microRNA linked to genes in the liver that are involved in cholesterol metabolism.

The results were published in the journal Nature, along with other test-tube research showing that LNA effectively blocks the production of hepatitis C virus in human liver cells.

Santaris intends to test its first LNA compounds in humans by the middle of this year but it will take at least five years before any medicine is ready for submission for approval.