Application of Bilski to Medical Treatment Claims

In its decision in In re Bilski, the Federal Circuit Court of Appeals held that a claim to a process only sets out patent-eligible subject matter if the claim requires use of a particular machine or involved a transformation of something to a different state or thing and that a claim was not patent-eligible if it pre-empted all uses of a natural phenomenon. Although the United States Supreme Court has agreed to review it, there has been concern about whether certain claims for medical treatments or methods for diagnosis would meet the transformation test set-out in the Bilski decision.

A panel of the Federal Circuit has now addressed some of these concerns in Prometheus Laboratories Inc. v. Mayo Collaborative Services.

The basis of the invention was a finding that the blood levels of certain metabolites of some thiopurine drugs used for treatment of immune mediated gastrointestinal disorders correlate with toxic side effects of the thiopurine drugs. The claims were directed to a method of optimizing therapeutic efficacy for a treatment of such conditions by administering a drug “providing” the metabolite whose levels were to be measured to a subject and determining the level of 6- thioguanine in the subject and administering a drug providing 6-thioguanine in an amount correlated to the levels found by the determination. The District Court for the Southern District of California held that this finding was a discovery of a natural phenomenon (the correlation of the side effects with the levels of a particular metabolite) and that the claim would wholly preempt use of this natural phenomenon and so failed to meet the requirements of 35 USC 101.

In its decision of September 17, 2009, the Federal Circuit disagreed.

The Court, in a decision authored by Judge Lourie, found that both the administration and the determination steps required by the claim involved “transformations”. In the administration step, the human body was transformed following the administration of the drug. The court noted that such transformation occurred “following administration of a drug and the various chemical and physical changes of the drug’s metabolites that enable their concentrations to be determined.”

So far as the determination step was concerned, this also involved a transformation because “determining the levels [of metabolite] in a subject necessarily involves a transformation, for these levels cannot be determined by mere inspection”. The manipulation of the samples from the subject by, for example by high pressure liquid chromatography, to make the necessary determination of metabolite levels transformed these samples into something different from the sample as taken from the subject. Such steps were not mere “insignificant extra solution activity” or “data gathering” as had been held in Bilski to be inadequate to render claims that otherwise lacked a transformation or use of a special machine to become patent-eligible, but rather

central to the purpose of the claims, since the determining step is, like the administering step, a significant part of the claimed method of treatment. Measuring the levels [of metabolites] is what enables possible adjustments to thiopurine drug dosage to be detected for optimizing efficacy or reducing toxicity during the course of treatment.

It was true that there was a mental element involved in what was claimed, but simply because a claim included a mental step did not preclude the subject matter from being patent-eligible if a true transformation was also present. In support of this, the court again, as it had done in Bilski, cited with approval the decision in In re Abele where claims to transformation of X-ray attenuation data into a particular visual depiction of a physical object had been found sufficient for patent eligibility but claims to calculating and graphically displaying variances of data from average values irrespective of what they represent were not patent-eligible.

So far as the reasons given by the district court to find the claimed method was not patent-eligible, the Federal Circuit found that

The claims cover a particular application of natural processes to treat various diseases, but transformative steps utilizing natural processes are not unpatentable subject matter. Moreover, the claims do not preempt natural processes; they utilize them in a series of specific steps.

Having found that the claims met the transformation limb of the Bilski test, the court found it unnecessary to consider Prometheus’ argument that to make the determination required in the claims, special machines were required.

Although the decision does not address the concerns that have been raised as to whether the Bilski reasoning precludes the grant of claims directed to methods of diagnosis that involve only acts of comparison of results, the reasonably broad interpretation of “transformation” in the Prometheus decision should alleviate many of the concerns that have been raised.