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Patent drafting is often like taking a snapshot of a moving car: A part of the car’s image — the invention at the time the patent application is filed — will be in focus, and the remaining details — the prophetic description of the downstream products of the invention — will be fuzzy. This is especially true when successive patent applications are filed on an invention that evolves over many years. The scope of the patent is a function of both what is taught when the application is filed and how the technology develops. How that development is managed has a critical impact on whether the patent is ultimately enforceable. The U.S. Court of Appeals for the Federal Circuit recently commented on the effect of technological evolution on patent interpretation in its March 2004 decision in Chiron v. Genentech, when it ruled that Chiron’s patent did not cover Genentech’s breast cancer treatment Herceptin. The ruling puts the patent bar on notice: To keep patent applications from getting too “stale,” corporate patent lawyers must now coordinate even more with researchers and business developers. The technology in dispute in Chiron dates back to the early 1980s. Scientists at Cetus (later acquired by Chiron) searched for antibodies that could target breast cancer antigens — the molecular markers that tell the immune system that cells are cancerous — and discovered the human c-erbB-2 antigen. (This became known later as the HER2 antigen.) In 1984, 1985, and 1986 Cetus filed three patent applications on mouse-generated antibodies to this antigen. A patent issued in April 2000. On its face, Chiron’s patent appeared to cover any antibody-based therapeutic directed to the HER2 antigen, which would include Herceptin. Yet the Federal Circuit found that Herceptin did not infringe Chiron’s patent. The patent may have identified the ultimate target of the Herceptin product, the court said, but it did not demonstrate sufficiently that Chiron could teach those of appropriate skill how to make and use such a product. The court reasoned that an effective therapeutic requires technology to produce chimeric antibodies (antibodies comprising parts of two or more species). And Chiron’s original 1984 application predated the first publications of chimeric antibody technology. Chiron could not have possessed or taught something it could not have known. The court did say that by the time the next two applications were filed, chimeric antibody technology was known, but it was not widely known to those of ordinary skill in the field. Chiron could not rely on the general knowledge of the state of the art to support its claim. The court concluded that a person of skill would have to expend undue experimental effort to practice the broadly defined claims of the patent. Chiron demonstrates a serious pitfall for patent owners and practitioners working in fast-paced technologies: Often the meanings of key terms used in patent claims, as well as the subject matter claimed, evolves over time. Sometimes even the definition of the subject matter itself shifts. The effects of such changes, however, are not always obvious from the descriptions in the original patent applications. This can result in some pretty unpleasant surprises. Such surprises can be avoided when inventors keep patent practitioners abreast of developments in the field. As understanding and terminology evolve, pending applications must be reviewed to determine whether they are still relevant. Patent practitioners should also work with business developers to define goals for what the patent application should cover — often the key to success. Research, business, and IP management must be more product-focused, so that critical information can be added promptly to patent applications. Chiron also presents another dilemma. We cannot rely on the Patent and Trademark Office to catch disclosure problems early. Right now, the only way to challenge patents of questionable support — many far broader than Chiron’s in terms of claim scope and more narrow in teaching — is through (expensive) litigation. Patent examiners are woefully unprepared to evaluate the adequacy of the written and enabling descriptions supporting the pending claims. One way to fix the problem is to provide for a post-grant review before the patent office. These could be performed using special masters with knowledge relevant to the patent in question. The cost of providing such a review would be much lower, and more reliable, than litigation. David P. Lentini is a senior counsel at Foley & Lardner.

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