Calando Pharmaceuticals, a majority owned subsidiary of Arrowhead Research Corporation (NASDAQ:ARWR), announced on May 13 the issuance of Chinese Patent No. 28266625, entitled “Methods and compositions for therapeutic use of RNA interference.” The Chinese patent broadly covers all methods of using any RNA interference (‘RNAi’) construct formulated “in a supramolecular complex” to attenuate the expression of any target gene. Supramolecular complex formulations are any that are formed with any type of polymer. The patent also broadly covers all pharmaceutical compositions of matter containing RNAi constructs “adapted for pulmonary or nasal delivery” to the lungs.

The therapeutic potential of RNAi-based drugs cannot likely be fulfilled unless they can effectively be delivered to target tissues. The Chinese patent provides a basis for delivery of RNAi-based drugs in patients of the world's most populous country; and with respect to respiratory pharmaceuticals, the Chinese patent is not limited to any specific mode of siRNA delivery.

"We are pleased that the Chinese Patent Office has affirmed the pioneering efforts of Calando in the area of RNAi delivery," said James Hamilton, Calando's CEO. "This patent greatly enhances Calando's dominant international intellectual property position with respect to the delivery of RNAi-based drugs." Calando's CALAA-01 has been cleared by the FDA to begin phase I clinical trials and is on track to be the first clinical study using targeted, systemic delivery of siRNA and the first siRNA trial in oncology.

RNA interference, or RNAi, is a naturally occurring mechanism within cells for selectively silencing and regulating specific genes. Since many diseases are caused by the inappropriate activity of specific genes, the ability to silence genes selectively through RNAi could provide a new class of medicines to treat a wide range of human diseases. RNAi is induced by small, double-stranded RNA molecules. One method to activate RNAi is with chemically synthesized small interfering RNAs, or siRNAs, which are double-stranded RNAs that are targeted to a specific disease-associated gene. The siRNA molecules are used by the natural RNAi machinery in cells to cause highly targeted gene silencing.