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Key RNAi-Based Drugs in the Clinic


Alnylam Pharmaceuticals

ALN-RSV01, an siRNA-based treatment for respiratory syncytial virus, entered phase I testing in late 2005. The drug, which targets the nucleocapsid N gene of the RSV genome, moved into phase II testing in mid-2007 in healthy adults experimentally infected with the virus. A second phase II trial — this time in adult lung-transplant patients naturally infected with the virus — began in early 2008.

This summer, Alnylam said that ALN-RSV01 met the primary endpoints of safety and tolerability in that second study, and is on track to enter a follow-on phase II trial in a larger population of RSV-infected lung-transplant patients in 2010. A next-generation molecule, ALN-RSV02, is slated to enter a phase I trial in a pediatric population next year. That drug has been licensed to Cubist Pharmaceuticals.

ALN-VSP is a cocktail of two siRNAs, one targeting vascular endothelial growth factor and the other targeting kinesin spindle protein, being developed as a liver cancer therapy. The drug entered phase I testing in patients with advanced liver cancers early this year.

Calando Pharmaceuticals

CALAA-01 is an siRNA-based cancer therapy targeting the M2 subunit of ribonucleotide reductase. In June 2008, it entered phase I testing in patients with solid tumors, becoming the first formulated RNAi drug to be tested in humans. That trial is ongoing.


PF-4523655, formerly RTP801i-14, is an siRNA drug targeting RTP-801, a gene found to play a role in angiogenesis, vascular permeability, and retinal neuron death. Originally developed by Quark Pharmaceuticals, Pfizer licensed the drug and target in 2006.

The drug entered phase I development in early 2007 for wet age-related macular degeneration, and is currently in phase II testing for both AMD and diabetic macular edema.

Silence Therapeutics

Atu-027 is a blunt-ended siRNA targeting the protein kinase PKN-3. Originally developed by Atugen, which was later acquired by Silence, the cancer drug entered a phase I study in patients with solid tumors this summer. According to Silence, the trial is scheduled to wrap up around the end of 2010.


SYL040012 is an siRNA designed to inhibit adrenergic receptor beta-2. Sylentis’ first RNAi drug candidate, the glaucoma therapy began a phase I trial in September.

Tekmira Pharmaceuticals

ApoB SNALP is an siRNA-based hypercholesterolemia drug targeting apolipoprotein B that in July entered a phase I study of patients with elevated low-density lipoprotein cholesterol. Tekmira said that study is expected to be completed in early 2010.


TD101 is an investigational treatment for the rare skin disorder pachyonychia congenita caused by a mutation in any one of the dozens of genes encoding keratins. The drug, which targets a particular mutation in one of these genes, entered a single-patient phase I study in early 2008.

In that study, the drug was administered via intradermal injections. A planned follow-on study is expected to use a cream-based, topical delivery vehicle, but the expected start date of the trial is unknown.

Quark Pharmaceuticals

QPI 1002, formerly AKIi-5, is an siRNA being developed as a treatment for acute renal failure. It is designed to temporarily inhibit expression of the pro-apoptotic gene p53.

The drug moved into phase I testing in patients undergoing major cardiovascular surgery in late 2007, becoming the first systemically administered RNAi drug to be tested in humans. A second phase I trial is ongoing. The drug also entered phase I/II development early this year for the prevention of delayed graft function in patients undergoing deceased donor kidney transplantation.


Excellair is an siRNA targeting the intracellular kinase Syk. Delivered directly to the lung, the drug entered phase I testing in late 2008. Phase II testing began in September.