Did Pfizer get punked by a nonprofit? The U.S. Patent and Trademark Office (USPTO) issued a ruling on one of several patents that Pfizer holds on Lipitor (atorvastatin), its top-selling cholesterol drug. In the reexamination proceeding initiated last year by the Public Patent Foundation (“PUBPAT”), the USPTO rejected all 44 of the claims of U.S. patent 5,969,156 when it ruled that Pfizer’s arguments for securing the patent in 1999 were invalid.

Each of the 44 claims of the ‘156 patent claim crystalline atorvastatin, known by the chemical name [R-(R*,R*)]-2-(4-fluorophenyl)-beta,delta-dihydroxy-5-(l-methylethyl)- 3-phenyl-4-[(phenylamino)carbonyl]-1 H-pyrrole-1-heptanoic acid hemi calcium salt. The claims of the ‘156 patent differ only in having limitations regarding either (a) X-ray powder diffraction values, (b) solid-state 13C nuclear magnetic resonance chemical shift differences, or (c) moles of water. PUBPAT’s Request for Re-examination alleged that the claims of the ‘156 patent are anticipated by U.S. patents 5,273,995 and 5,686,104 as having disclosed crystalline atorvastatin.

The USPTO has now rejected the claims as unpatentable under 35 U.S.C. 103(a) over US 5,273,995 (‘995) and/or US 5,686,104 (‘104). The Examiner contends that the ‘995 patent teaches a specific enantiomer of the racemic atorvastatin although admitting that it is not absolutely clear if the compound disclosed in the ‘995 patent is amorphous or crystalline. However, in col. 15, line 51, the word “recrystallized” is recited, which the USPTO says implies that the compound was initially crystallized. On this basis, the Examiner assumed that the compound in the ‘995 patent existed in a crystalline form unless Pfizer can show otherwise.

Likewise, the ‘104 patent teaches essentially the same compound of ‘995 (col. 2, lines 60-63), however in a more stable oral pharmaceutical composition. The ‘104 patent is silent to the crystallinity of the atorvastatin compound used and hence may be redundant of ‘995. Pfizer may be able to show that the compound in the ‘104 patent is different from that of ‘995 in terms of amorphism or crystallinity.

However the USPTO indicated that the more pertinent question is whether or not the compounds of the ‘104 patent and/or the ‘995 patent are different crystalline forms of atorvastatin compared to those of the current patent. If the former is true then Pfizer needs to make a showing over both the compounds (provided that they are crystalline, if they are amorphous, no showing is needed), alternatively, if the latter is true then only one showing is needed. The USPTO also took note of US patent 6,605,636, where the compound in US patent 5,273,995 is referred to as crystallized.

So, it’s not over yet and generics won’t show up at the local pharmacy tomorrow. This is just an obviousness rejection (sec. 103) and the presumption can be rebutted. Pfizer will now have two months to respond to the Patent Office’s rejection while PUBPAT can no longer participate in the process. It is worth noting, though, that third party requests for reexamination, like the one filed by PUBPAT, result in having the subject patent either modified or completely revoked about 70% of the time.

For instance, the ‘156 patent attempts to distinguish itself over the prior art by stating it discloses “atorvastatin in a pure and crystalline form to enable formulations to meet exacting pharmaceutical requirements and specifications.” even though none of the claims contain any limitation regarding pharmaceutical requirements or specifications. It is possible that the patent will eventually emerge with some additional limitations added to the claim language.

The ruling doesn’t affect the company’s two most important patents on atorvastatin, which give Pfizer the exclusive right to Lipitor through March 2010 and June 2011, respectively. However, these patents are the subjects of litigation with generic pharmaceutical company Ranbaxy Laboratories Ltd. The ‘156 patent at issue with the current re-exam was set to expire in 2017, thus extending the useful patent protection of the drug (keep in mind that Lipitor is set to become the world’s first $10-billion-a-year drug so the stakes are extremely high).

Although the rejected patent is one of five patents listed by Pfizer with the U.S. Food and Drug Administration (FDA) for atorvastatin, it is the only one asserted by Pfizer in roughly two dozen patent infringement lawsuits filed last year against web sites selling generic atorvastatin to Americans. Two are under review by a Delaware court and the remaining two have never been asserted by Pfizer against any competitor to Lipitor.

The Public Patent Foundation (“PUBPAT”) is a not-for-profit legal services organization that claims to represent “the public’s interests against the harms caused by the patent system, particularly the harms caused by wrongly issued patents and unsound patent policy.” It’s not clear who may be really behind this (or providing the funding for it) but it received seed funding from the Echoing Green foundation. You can see the Board of Directors here.

Download the USPTO Office Action in Ex Parte Reexamination here.

More information about the reexamination of Pfizer’s Lipitor patent can be found at PUBPAT.

Download the PUBPAT Re-examination Request here.

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