ALN-TTRsc02 is a treatment that Alnylam Pharmaceuticals is developing for familial amyloid polyneuropathy, or FAP, and other types of ATTR amyloidosis.

How ALN-TTRsc02 works

FAP is a condition characterized by the buildup of abnormal deposits of proteins, or amyloids, in different organs and tissues.

It is caused by mutations of the TTR gene, which provides the instructions necessary to produce a protein called transthyretin. Transthyretin transports vitamin A and a hormone called thyroxine throughout the body.

ALN-TTRsc02 targets faulty mRNA, the intermediate messenger molecule between the TTR gene and transthyretin protein. By binding to TTR mRNA, ALN-TTRsc02 triggers a natural process called RNA interference that promotes the destruction of mRNA. RNA interference prevents the production of the faulty transthyretin protein that causes the disease.

ALN-TTRsc02 in clinical trials

ALN-TTRsc02 is in early clinical trial stage. A Phase 1 study (NCT02797847) is aimed at determining the safety, tolerability, pharmacokinetics, and pharmacodynamics of increasing doses of ALN-TTRsc02 in healthy volunteers. Pharmacokinetics refers to the body’s effect on a drug, while pharmacodynamics refers to a drug’s effect on the body.

Researchers are looking at whether ALN-TTRsc02 triggers changes in participants’ health. They are also studying any impact the drug might have on the body by assessing levels of transthyretin protein and vitamin A in blood. Safety measurements will include vital signs, physical examinations, laboratory evaluations, electrocardiograms, and adverse events monitoring.

The starting dose patients receive is 25 mg. It can be increased to a maximum of 600 mg as researchers try to determine the ideal dose for safety and effectiveness. The study will last around five months for each participant. Final results are expected in January 2018.

Preliminary data showed that the 48 participants tolerated ALN-TTRsc02 well. Patients experienced no serious adverse events, and none had to discontinue the treatment due to side effects. Adverse events were mild or moderate. They included redness and pain at the injection site, itching, cough, nausea, fatigue and abdominal pain.

A single 25-mg dose of ALN-TTRsc02 reduced the production of transthyretin protein by up to 98.4 percent for more than four months, while a 50-mg dose reduced it by 86.2 percent.


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