In vivo conversion is a process, often metabolic in nature, wherein one substance, usually a chemical compound, is altered significantly by physiological pathways in the body into one or more different substances. For example, when a patient ingests a therapeutic drug, that drug is often converted by the natural physiology of the digestive system into one or more chemically different metabolites. The end products of in vivo conversion sometimes possess therapeutic efficacy. Many patent applications have claimed such therapeutic metabolites, either as compositions per se or as parts of methods of treatment. Although the United States Patent and Trademark Office has granted patent claims to such products generated by in vivo conversion of ingested drugs, and courts have noted the eligibility of such products as patentable subject matter, never has a United States court of final appeal upheld such a patent claim as valid, enforceable, and infringed. The unanimity of results in cases involving patent infringement triggered by in vivo conversion is striking. In fact, its very improbability suggests a common underlying explanation for why in vivo conversion does not ever seem to trigger patent infringement. Explanations based on inherency or a lack of evidence provide a satisfactory explanation for only a minority of in vivo cases. The "Physiological Steps Doctrine," which suggests that products and processes of in vivo conversion are unpatentable subject matter under United States patent law, offers an explanation that spans all in vivo conversion cases. Though the rationales offered to explain the results in a number of in vivo conversion cases are suggestive, there are several advantages for a more explicit recognition of the Physiological Steps Doctrine. Consistent with much international, European, and U.S. patent law, the Physiological Steps Doctrine provides a theoretical underpinning to explain the results in cases involving products and processes of in vivo conversion. This theoretical underpinning not only has explanatory power for interpreting previous case law but is also useful in predicting the outcome of future in vivo conversion cases. In addition, the Physiological Steps Doctrine increases the understanding of where inventions involving human beings, and the biological products and processes thereof, fit within the spectrum of patentable subject matter.On March 20, 2012, the United States Supreme Court unanimously confirmed Physiological Steps Doctrine by holding invalid Prometheus Laboratories' patent claims to uses of in vivo conversion products in diagnosis and therapy. The decision, Mayo Collaborative Services v. Prometheus Laboratories, Inc. (U.S. 2012), may not only sound the formal death knell of in vivo conversion patents, but also cast severe doubt on the patent eligibility of wide swaths of the personalized medicine and genomics fields. LEXVIVO has discussed previous chapters in the Prometheus saga by the Supreme Court and the Court of Appeals for the Federal Circuit ("CAFC").
It would now be unsurprising if the Supremes were to vacate and remand the July 29, 2011, CAFC decision in The Association for Molecular Pathology, et al. v. Myriad Genetics, Inc., et al. (previously discussed on LEXVIVO) that upheld the patent eligibility of gene patents. If so, genome-derived DNA patents could be the next domino to fall in the recently turbulent game of patentable subject matter.