On Thursday, October 25, the U.S. District Court for the District of Delaware held that two Bayer (BAY) patents on Avelox (moxifloxacin hydrochloride) are valid and enforceable, and are infringed by Dr. Reddy's (NYSE:RDY) ANDA for a generic version of Avelox. The Opinion (pdf) and Order (pdf) follow a week-long bench trial held in August 2006. Avelox is an antibiotic commonly used for the treatment of respiratory tract and other infections, with annual U.S. sales of $340 million.
The first of the two patents-in-suit, U.S. Patent No. 4,990,517, generically claims millions of quinolone compounds. Moxifloxacin is one of many compounds listed in the '517 specification. It had not yet been synthesized at the time the application was filed. The second patent-in-suit, U.S. Patent No. 5,607,942, claims a specific quinolone and its four stereoisomers, one of which is moxifloxacin.
Dr. Reddy's asserted that the '517 and '942 patents are invalid for obviousness, and are unenforceable due to inequitable conduct, and that the '942 patent is invalid for double patenting over the '517 patent. With respect to obviousness, Dr. Reddy's asserted that one would have been motivated to modify a prior art compound at the 7-position; one would have been motivated to use a diazabicyclo octane [DBO] substituent at the 7-position; and through routine experimentation, one would have made compounds covered by the asserted claims. Quoting KSR, the district court stated that "Reddy must identify some reason that would have prompted a person of ordinary skill in the relevant field to combine these elements to yield the claimed compounds." Moreover, according to the district court, "Reddy must demonstrate that such a person would have had a reasonable expectation of success in doing so."
The parties disputed whether Dr. Reddy's was required to demonstrate why a person of ordinary skill in the art would have selected a particular lead compound to modify in the first place. The district court sided with Bayer, citing the Federal Circuit's recent decision in Takeda v. Alphapharm as "affirming the district court's finding that defendant failed to prove a prima facie case of obviousness where the prior art disclosed a broad selection of compounds, any one of which could have been selected as a lead compound for further investigation, and defendant did not prove that the prior art would have led to the selection of the particular compound singled out by defendant." The district court further found that Dr. Reddy's failed to demonstrate a motivation to modify a lead compound with DBO, or a reasonable expectation of success in making the proffered combination of prior art.
According to Bayer's press release announcing last Thursday's court decision, Teva (NYSE:TEVA) has also challenged the validity of the same Bayer patents at issue in the Dr. Reddy's case. Bayer's case against Teva is also pending in the District of Delaware, with trial currently scheduled to begin on February 25, 2008.
In addition to the '517 and '942 patents, the Orange Book lists two other Bayer patents for Avelox: U.S. Patent No. 5,849,752, directed to a crystal form of moxifloxacin; and U.S. Patent No. 6,610,327, claiming pharmaceutical formulations of moxifloxacin. It is unclear how Dr. Reddy's and Teva intend to deal with those patents.