Originally published by The National Law Journal on April 9, 2012.
"Hard cases make bad law" is an old saying in the
study of law. The U.S. Supreme Court's recent decision in
Mayo v. Prometheus Laboratories falls into this category.
In a unanimous decision issued on March 20, two patents that
Prometheus had sought to enforce against Mayo Laboratories were
struck down because the Court concluded that the patent claims were
directed to natural laws and, hence, not eligible for patent
protection.
The decision, authored by Justice Stephen Breyer, has sent a
shockwave through the biotechnology industry because the
Court's reasoning may lead to the demise of diagnostic-method
patents and remove the financial incentives that are currently
propelling the growth of personalized medicine. If Breyer's
reasoning is broadly applied, it is also hard to see how any
diagnostic or even medical treatment method claim can survive
scrutiny.
The principal claim at issue in the Mayo case recited a first step
of administering a drug to a patient and a second step of measuring
the level of a particular metabolite in the patient's blood and
a "wherein" clause that described a level above which
there is a likelihood of harmful side-effects and below which the
drug dosage may be ineffective. The claim was drafted this way to
cover any supplier of an assay that would measure the particular
metabolite.
The Court found this "wherein" clause to be, in essence,
an appropriation of a law of nature and not the sort of thing that
should be patentable. Breyer compared the claim to Einstein trying
to patent E=MC² or Newton trying to capture the law of gravity
in a patent. Relying on a decision from the early days of the age
of computers that found claims to a mathematical algorithm to be
unpatentable because the claims were "so abstract and sweeping
as to cover both known and unknown uses" of the formula,
Breyer reasoned that the Prometheus claims would likewise
"risk disproportionately tying up the use of underlying
natural laws, inhibiting their use in making further
discoveries."
But was the discovery claimed in the Prometheus patent truly an
abstract law of nature? The patent solved a known problem, namely
selecting the right dosage for a very specific class of drugs that
patients metabolize differently. Because of the metabolic
differences, a dosage that is good for one patient is not
necessarily good for another. The patent claim recited the
metabolite levels that were too high and those that were too low
— in essence identifying the sweet spot for therapeutic
efficacy. This was a practical application of science, not an
abstraction like the law of gravity.
The problem with the Court's reasoning is that every diagnostic
invention is at its core a discovery of a natural correlation
between a biomarker or other analyte and a medical condition.
Historically, the question that governed patentability of
diagnostic methods, such measuring prostate-specific antigen as an
indicator of prostate cancer or high-density lipoprotein as sign of
unheathy cholesterol, has been whether the correlation discovered
by the inventor was new and unobvious to one skilled in the art
— not whether the correlation embodied a law of nature.
How can any diagnostic method claim still be eligible for patent
protection if the law now precludes diagnostic methods that rely on
a scientific principle or law of nature? Would Breyer prefer
diagnostic methods be based on lucky guesses or Ouija board
results?
Though not at issue in the Mayo case, the Court's logic in the
Mayo decision also casts a shadow on method-of-treatment claims.
For more than 200 years, the U.S. patent laws have allowed patent
protection — in the form of method claims — for
new and unobvious medical treatments with known drugs or agents.
Many other countries do not allow patent claims for human treatment
but the U.S. laws do — or did. Congress has from time to
time debated the value of allowing method of treatment claims.
Several years ago Congress did impose some limitations on surgical
methods (requiring that the claims also recite a novel surgical
instrument) but Congress did not abolish medical-treatment
claims.
However, the logic of the Mayo decision may put medical treatment
claims into the "patent ineligible" category, as well.
For example, a claim such as "treating a retroviral infection
with an effective amount of AZT" (to paraphrase the famous
first AIDS drug patent) could be suspect since it could also be
considered to be a claim to a law of nature. AZT works by
inhibiting reverse transcriptase, an enzyme necessary to the
retroviral replication. The AZT inventors discovered this "law
of nature."
A less ominous reading of the Mayo decision is that the Supreme
Court simply felt that there wasn't enough meat in the
Prometheus claim and perhaps a more specific recitation of the
assay steps would have passed muster. If so, then the decision
leaves to the lower courts the dirty work of sorting out how much
more specific a diagnostic claim must be.
This process of leaving it up to the lower courts to divine the
meaning of the Mayo case has already begun. A few days after its
Mayo decision, the Supreme Court granted a petition to review
another hotly contested case involving Myriad Pharmaceutical's
patents on isolated breast cancer gene sequences — and
then immediately remanded the case back to the U.S. Court of
Appeals for the Federal Circuit, from whence it came, to reconsider
its decision in light of the Mayo ruling.
It is most unfortunate that the Supreme Court's decision in the
Mayo case only discussed one claim of the Prometheus patents. There
were several more specific dependent claims in the Prometheus
patents that explained how the assay should be conducted, e.g., by
measuring metabolite levels in red blood cells or by use of high
pressure liquid chromatography. The biotechnology industry and
patent practitioners would have benefited from some explanation as
to why these claims were likewise unacceptable. Instead, the
Supreme Court just kicked the can down the road.
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