Federal Circuit Clarifies Prosecution Laches

The facts of Cancer Research Tech. v. Barr Labs., Inc., App. No. 2010-1204 (Fed. Cir. November 9, 2010) (PDF at end of post) are almost more interesting than the holding, which is : “We…now hold that to establish [the prejudice necessary for a finding of prosecution laches] an accused infringer must show evidence of intervening rights. Since the accused infringer, Barr, was seeking approval of an ANDA on a drug patented by Cancer Research Tech., and brought to market by Schering (not surprisingly) well before Barr filed its ANDA, Barr was not going to be able to meet this burden.

However, the back-story is of some interest to patent prosecutors in the life sciences/pharma area, if only for the light it sheds on PTO prosecution policy. The original application for the patent-in-suit, that covers the anti-cancer drug Temodar, was filed in 1982. In November 1983, in the first substantive office action, the Examiner rejected the claims to a method for treating leukemia as facially lacking utility because leukemia was clearly untreatable, and went on to say that utility could be established by FDA approved tests. The Examiner cited Ex parte Timris, which, ironically was one of the first Board decisions to hold that methods of medical treatment are patentable subject matter. Of course, we take this for granted, as the Fed. Cir. did recently in Prometheus v. Mayo, but Timris was a 1959 decision, not an 1859 decision(!). Still, Examiners threw up every imaginable legal and policy roadblock to support lack of utility and nonenablement rejections of claims to compounds and their uses disclosed to be useful to treat cancer, and then AIDS, at least well into the 90’s. (Just a few years ago, an Examiner asserted that the PTO was the “gatekeeper for the FDA” but that’s another story.)

In vitro inhibition of cancer cells was routinely disregarded. Ex parte Balzarini,(1991), the Board agreed with the Examiner that in vitro efficacy of anti-HIV drugs did not correlate to an expectation of success of human treatment, providing unwarranted difficulties to applicants seeking to slow the epidemic. It was not until In re Brana in 1995 that the Fed. Cir. held that animal models of human disease could suffice to establish utility/enablement in the case of an anti-cancer drug. This holding did not help those of us prosecuting claims to potential anti-HIV drugs, since there was no readily available animal model for the disease but, to its credit, the PTO informally ignored Balzarini almost before it was decided, at least in the HIV area. Interestingly, the Cancer Research Tech. decision mentions that Cancer Research eventually cited In re Buting, a 1969 CCPA decision that held, as did Brana, 27 years later, that positive test results in accepted animal models could establish utility of a compound in humans.

But I digress. Applicant did not argue the rejection, but filed and re-filed the application and then assigned it to Cancer Research, who eventually licensed it to Schering. The patent in suit issued in 1993, following eleven continuations, and presentation of rebuttal arguments by applicants regarding utility. By that time, as noted above, most Examiners, would issue patents on anti-cancer drugs based on, at the least, a showing of utility based on animal testing. Tremodar was approved by the FDA in March 2005 to treat a form of glioblastoma. Schering listed the patent in the Orange Book and got patent term extension and pediatric exclusivity, so that the patent would not expire until 2014.

Barr filed an ANDA in 2007 and the issues were boiled down to invalidity due to prosecution laches and inequitable conduct. The Fed. Cir. agreed with Cancer Research that prosecution laches should require both unreasonable and unexplained delay AND prejudice based on intervening rights of the defendant or the public during the period of delay. Interestingly, Cancer Research argued that the chain of continuations was needed, since it had a good faith belief that clinical data would be required to overcome the Examiner’s lack of utility rejection. As noted above, that line of argumentation is a stretch. However, the Fed. Cir. may well have been swayed by the facts that the patent issued about when Schering partnered with Cancer Research, and the IDA was filed shortly thereafter. The court also noted that Barr could have filed its ANDA four years earlier than it did. The district court’s finding of prosecution laches was reversed. So was the finding of inequitable conduct. The withheld information may have been material, but the court found that the requisite intent was missing. The inventor had published “pro“ and “con” data widely, thus evidencing that he did not appreciate their importance to patentability.

cancer research v barr

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