Marina Biotech Demonstrates In Vivo Knockdown of a microRNA With a CRN-Modified Antagomir
Product News Aug 11, 2011
Marina Biotech, Inc., has reported in vivo data demonstrating up to 2.5-fold derepression of down-stream targets of a well-established microRNA, miR-122, with a Conformationally Restricted Nucleotide (CRN) modified antagonist.
Derepression of down-stream targets represents the intended therapeutic benefit of inhibiting a specific microRNA controlling those targets; allowing the down-stream targets to express proteins which the microRNA typically down regulates.
Thus, microRNA inhibition is one of the few therapeutic approaches that permits "upregulation" of specific gene targets. The CRN modified antagonist was highly effective at a dose of 10 mg/kg, while demonstrating good tolerability with repeat dosing.
"In vivo efficacy is a significant milestone in the advancement of our CRN technology and for our broad nucleic acid-based drug discovery platform," stated Barry Polisky, Ph.D., Chief Scientific Officer at Marina Biotech.
Polisky continued, "Success in establishing this drug discovery platform requires the capability to pursue both double-stranded and single-stranded oligonucleotide therapeutics. The work we've recently completed demonstrates that our proprietary CRN technology can increase the affinity of a single-stranded oligonucleotide to its intended target, whether it is a messenger RNA or microRNA. With our CRN and Unlocked Nucleobase Analog (UNA) technologies we have demonstrated that we can develop highly specific and potent double-stranded and single-stranded oligonucleotides. The combination of these unique chemistries and our multiple delivery technologies allows us to provide multiple nucleic acid-based approaches to our partners, and places us in a unique position within the field of nucleic acid-based therapeutics."
The identification and evaluation of microRNAs is one of the fastest growing fields in biology and medicine. MicroRNAs are considered to be key elements in maintaining normal cell physiology as microRNAs appear to be "central regulators of gene expression" that are critical for intra- and extra-cellular events.
Thus, either the loss of specific microRNAs or the overexpression of specific microRNAs can lead to abnormal cell processes that are the underlying basis for disease. Inhibition of an aberrant microRNA with an antagonist, as demonstrated by the results present here, or the supplementation with a microRNA mimetic can restore the much needed balance between cellular communication pathways.
Nucleic acid-based therapeutics are likely to be the most direct and efficient means of modulating the function of microRNAs, and are expected to provide much needed treatments of cancers and other diseases.
"With the completion of this early work with our CRN chemistry, we now have in vivo demonstration of our ability to develop single-stranded oligonucleotide therapeutic compounds," stated J. Michael French, President and CEO of Marina Biotech.
French continued, "These results are the culmination of almost a year's effort in advancing the CRN technology. Further, we now have in vivo proof of concept across our entire nucleic acid-based therapeutic platform demonstrating the ability to silence gene targets through either RNA interference or translational blocking, or via a microRNA mimetic, and, in the case of these data, to up-regulate gene targets via a microRNA antagonist. I believe we have put together the broadest nucleic acid-based drug discovery engine in the industry and a one-of-a-kind platform upon which to build pharma partnerships."