Pfizer Inc. v. Watson Pharma., Inc.

Court rejects claims of obviousness, lack of written description, and derivation, and finds patent valid.

April 17, 2013

GENERICally Speaking

Case Name: Pfizer Inc. v. Watson Pharma., Inc., Civ. No. 10-357-RGA, 2013 U.S. Dist. LEXIS 12394 (D. Del. January 30, 2014) (Andrews, J.)

Drug Product and Patent(s)-in-Suit: Rapamune® (rapamycin/sirolimus); U.S. Pat. No. 5,100,899 (“the ’899 patent”)

Nature of the Case and Issue(s) Presented:  The ’899 patent claims a method for increasing organic or tissue transplant acceptance in a mammal by administering rapamycin with one or more other chemotherapeutic agents, which may be administered to inhibit transplant rejections without causing severe toxic side-effects. Watson filed an ANDA seeking to market a generic version of Rapamune. The Court held a bench trial. Watson conceded infringement but asserted that claims 1, 4, 5, and 7 of the ’899 patent were invalid under §103 as obvious, invalid under §102(f) alone or in combination with §103 because the claims were derived from someone other than the inventor, and invalid under §112 for lack of written description.

At trial Watson identified a lead prior art compound, FK-506, which has the same active moiety, hemiketal, as rapamycin. Watson also identified three prior art references describing the attributes of FK-506, which combined, would render the ’899 patent obvious. The Court rejected Watson’s arguments. The Court determined that Watson only demonstrated that the prior art suggested continuing to investigate rapamycin’s immunosuppressive properties and a reasonable expectation that those properties would continue to develop at an incremental pace. The Court found the patent nonobvious, particularly in light of the secondary considerations of teaching away, long felt need, and failure of others. The Court also rejected Watson’s derivation defense. Watson claimed that another person, Dr. Keogh, conceived of the invention and communicated it to the inventor of the ’899 patent, Sir Roy. Watson claimed this was evidence of the fact that Dr. Keogh told Sir Roy about the existence of rapamycin, about its structural similarity of FK-506, and about the prior art. Dr. Keogh also requested a sample of rapamycin. The Court rejected those arguments. The Court determined that everything that Dr. Keogh told Sir Roy was in the prior art and the request of a sample did not cure the deficiencies in the prior art. Watson’s last argument was that the ’899 patent lacked an adequate written description. The ’899 patent discloses the adverse events of administering rapamycin to dogs and pigs. Watson argued that since the patent claims avoiding severe toxic side effects and since side effects vary between species, more is required to meet the written description requirement. The Court rejected this argument because Watson failed to provide clear and convincing evidence that inter-species toxicity varies so much more than inter-species efficacy that more written description is required.

Why Pfizer Prevailed:  Pfizer prevailed against Watson’s obviousness claim because Watson failed to demonstrate that there was a reasonable expectation of success and due to secondary considerations. The Court found that the prior art contained mixed teachings regarding the effectiveness and toxicity of rapamycin. While containing the same active moiety, Watson’s lead prior art compound FK-506 is structurally different than rapamycin and was known to operate via a different mechanism than rapamycin. The Court also determined that there was a teaching away in the prior art, a long-felt need (even if on a small scale), and failure of others. Due to the lack of a reasonable expectation of success, particularly in light of the secondary considerations, the Court rejected the obviousness challenge. The Court rejected Watson’s derivation defense on the basis that it found Watson’s argument to be “unsupported and logically flawed.” Watson argued that Dr. Keogh’s request for a rapamycin sample combined with his statements to the inventor regarding the prior art would have made it obvious for Sir Roy to evaluate rapamycin in animal testing. The Court was not persuaded because Dr. Keogh testified that he did not believe that the prior art rendered the claim obvious. The Court rejected Watson’s last defense—lack of written description regarding adverse effects. The Court found that Watson failed to demonstrate that interspecies toxicity varied from interspecies effectiveness, and further found Watson’s evidence deficient since the testimony cited in support of Watson’s argument failed to address the difference between interspecies toxicity and effectiveness. The only evidence that Watson presented arguably describing this difference was one article published three years after the patent was filed.

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