Provectus Pharmaceuticals, Inc., a development-stage oncology and dermatology biopharmaceutical company, has received allowance from the United States Patent and Trademark Office (USPTO) of its patent application protecting the synthetic process used to produce the small molecule Rose Bengal. A notice of allowance is issued after the USPTO makes a determination that a patent can be granted.

Rose Bengal is the active pharmaceutical ingredient (API) in PV-10, Provectus' lead oncology drug candidate. The company's patent application [no. 12/884,833] entitled, "Process for the Synthesis of 4,5,6,7-tetrachloro-3',6'-dihydroxy-2',4',5',7'-tetraiodo-3H-spiro[isobenzofuran-1,9'-xanthen]-3-one (Rose Bengal) and Related Xanthenes," details a new process for the manufacture of Rose Bengal and related iodinated xanthenes in high purity. The process optimizes conditions to reduce the formation of certain transhalogenated impurities that are present in commercial grade material, in accordance with International Conference on Harmonisation (ICH) guidelines for control of impurities in API. The patent allowance provides protection for Rose Bengal API to 2031, and the allowed claims encompass any hypothetical process that controls the amount of transhalogenated impurities in Rose Bengal.

Dr Craig Dees,CEO of Provectus, noted, "Rose Bengal has had a long and colorful history, starting in the 19th century as a humble synthetic wool dye, then being used throughout the 20th century as a food dye and in several diagnostic agents. The allowed claims protect our novel synthesis process, which is key in manufacturing Rose Bengal to modern quality standards for pharmaceutical use in therapeutic agents. The discovery of a hallmark, uncontrolled impurity in material manufactured using conventional processes, and our work to eliminate this class of impurities, led to the novelty of this allowed application."

Dr Dees added, "The quality standards established through use of the new process augment the seven year orphan drug exclusivity previously granted for our melanoma and hepatocellular carcinoma indications and significantly strengthen our expanding intellectual property estate around use of Rose Bengal. From a commercial perspective, the patent allowance also ensures that Provectus meets pharmaceutical manufacturing standards in important geographical regions worldwide including the United States, Australia, the EU, China, India and Japan."