The Uncertain Fate of Diagnostic Method Patents

The United States Supreme Court heard oral arguments late last year in the case of Bilski v. Kappos, a case that is likely to redraw the boundaries of patent-eligible subject matter. Although the case primarily concerns “business method” patents, the Court’s decision may affect other “process” patents as well, especially medical diagnostic patents.

Bilski petitioned the Supreme Court to hear his case after the Court of Appeals for the Federal Circuit (CAFC) – the federal court of appeals responsible for patent matters – affirmed the rejection of his patent application. The CAFC ruled that his business method claims were not patentable subject matter. The Bilski ruling imposed a strict test for claiming inventions as processes or methods, the so-called machine-or-transformation test. According to this test, a method is eligible for patenting only if it is tied to a specific machine implementation or it transforms an article from one state to another.

Although the Bilski test was enunciated in the context of a method for hedging risk in commodity trading, it was soon recognized that applying this test to all method and process patents could wreak havoc on medical diagnostic inventions. Diagnostic inventions typically involve diagnosing illnesses or optimizing therapeutic treatments based on analytical measurements or detection of substances such as proteins, DNA or other markers. Strict application of the Biski test in the diagnostic field could lead judges and juries to conclude that the discovery of a correlation between a measurement or marker and an illness or treatment was merely a verification of a natural phenomenon without effecting any transformation that would be sufficient for patent eligibility.

As alarm grew over the possible demise of diagnostic patents, the CAFC recently had an opportunity to revisit its holding in Bilski. Without waiting for a decision on Bilski’s appeal to the Supreme Court, the patent appellate court ameliorated some of the concerns of the biotechnology and medical device companies in Prometheus Laboratories Inc. v. Mayo Collaborative Services.

In the Prometheus case, the patent at issue was directed to a method of determining whether the dosage of a drug being given to a patient should be adjusted based on measured levels of certain naturally occurring metabolites. Generally speaking, the claims included the steps of (a) administering the drug to a patient, (b) determining the levels of metabolites and (c) and comparing the measured metabolite levels with predefined values to “indicate a need” to increase or decrease the drug dosage to minimize toxicity and maximize efficacy.

The lower court had held that the claims were effectively directed to a naturally occurring correlation, namely, the correlation between the metabolite levels and toxicity/efficacy of the drug. As such, the lower court deemed the claimed subject matter as ineligible for patenting. The lower court gave short shrift to the steps of (a) administering the drug and (b) determining the levels of the metabolites as “merely data-gathering steps,” which did not render the claim eligible for patenting. With regard to indicating whether a change in the dosage would be needed, the lower court considered this limitation as a merely a mental step.

The patent appellate court, however, deemed the claims as including transformations that were central to their purpose. More specifically, one transformation was that of “the human body following administration of a drug and various chemical and physical changes of the drug’s metabolites that enable their concentrations to be determined.” More generally, the CAFC held that methods of treatment are “always transformative when a defined group of drugs is administered to the body to ameliorate the effects of an undesired condition.”

The CAFC further held that the step of determining the levels of the metabolites was also transformative and central to the claimed methods as it required manipulation of a sample extracted from a human subject, e.g., subjecting the sample to high pressure liquid chromatography. In other words, the metabolite levels cannot be determined by “mere inspection,” but rather require transforming an extracted sample from one state to another.

The Prometheus decision provides some comfort to the biotechnology industry because it endorses the eligibility for patent protection when the inventions are bioassays that involve administering a drug to a patient or analyzing a sample extracted from a patient. For example, in the field of personalized medicine, it now appears that methods of establishing the susceptibility of individuals to diseases based on biomarkers can be patent eligible as long as they involve detecting the biomarkers in a biopsy, blood or other extracted sample.

However, the Prometheus decision still leaves many questions unanswered. Some diagnostic methods do not require administration of drugs or extraction of body fluids. For example, consider glaucoma tests in which the strength of a puff of air bouncing off an eye is correlated with intraocular pressure. Can a transformation be found in the transient deformation of an eye?

Future diagnostic inventions will undoubtedly involve the use of optical, ultrasound or other non-invasive measurements without extracting body fluids. Consider the elusive Holy Grail for diabetes: a non-invasive blood glucose sensor. It would be a shame if a solution to this problem were ineligible for patent protection because the “non-invasive” technique didn’t extract bodily fluids.

The Supreme Court will have the final say on what constitutes patent eligible subject matter. Their decision may or may not address diagnostic inventions. In the interim, the Prometheus case at least provides comfort that many diagnostic methods will still be patent-eligible even under the Bilski machine-or-transformation test. However, for inventions that rely on non-invasive measurements, patent eligibility still is not clear.

- Tom Engellenner and Reza Mollaaghababa

This update is for information purposes only and should not be construed as legal advice on any specific facts or circumstances. Under the rules of the Supreme Judicial Court of Massachusetts, this material may be considered as advertising.