Can Medical Diagnostic Tests Be Patented?
By now you probably know that the Supreme Court issued a significant decision concerning the patentability of medical diagnostic test procedures last month in Mayo Collaborative Sciences v. Prometheus, Laboratories, Inc. We described the decision in a March 20 blog post. As we explained, this decision concerns the issue of "statutory subject matter," i.e., what are the types of things that can be patented as opposed to whether they are sufficiently new (i.e., novel and non-obvious) compared to the prior art.
What Types of Inventions are at Issue?
The invention in Prometheus involved the discovery of an optimum blood concentration window of thiopurine drugs. Other types of medical diagnostic tests concern genetic markers that are used to predict the likelihood of certain diseases occurring. In Prometheus, the Supreme Court held that patent claims directed to the use of the optimum thiopurine blood concentration window were too "abstract" to be patentable, even if the concentration window had never been previously discovered. The case has provoked strong reactions both from those who believe that medical diagnostic tests should be patentable and those who do not.
What Qualifies as Statutory Subject Matter?
As a law firm advising clients, our concern is less about what is patentable and more about the clarity of the rules for determining whether something is patentable. Companies need to know where to invest their intellectual property resources, and the lack of bright line legal rules impedes good decision making. Statutory subject matter has proven to be an elusive and difficult subject for decades. Unfortunately, the Prometheus decision makes things worse, far worse in the view of some.
It has been and continues to be the law that laws of nature, physical phenomena, and abstract ideas are not patentable, but that applications of them may be. Drawing the line between a patentable application and an unpatentable law, phenomena, or idea is difficult in practice. However, Prometheus muddies the water by injecting the issues of novelty and non-obviousness into the determination of whether something is statutory subject matter. Specifically, the Court ignored the concentration window (i.e., the law of nature or physical phenomenon) in the patent holder's claims and then considered whether the remaining claim elements were novel and non-obvious. Because the Court held that the other claim elements were well known, it concluded that the patent claims were invalid because they did not constitute statutory subject matter.
This type of analysis has not been sanctioned previously by the Supreme Court or the Federal Circuit Court of Appeals. Nor has it been applied by the U.S. Patent & Trademark Office. Therefore, those who hold medical diagnostic patents may find them vulnerable to an invalidity attack if the patents are asserted in litigation. Infringing competitors may start to sprout up. Licensees may feel emboldened to stop paying royalties.
Can Companies Work Around the Prometheus Decision?
The Prometheus decision leaves open a key question, the answer to which may determine whether and to what extent strategies can be developed to better ensure that medical diagnostic methods can be successfully patented. We discussed this question in our March 26 blog post.
The key question is whether claims may be statutory if they recite an affirmative treatment step. The Prometheus claims did not require anything to be done with the test results. They simply stated that when the blood concentration of thiopurine drugs was above an upper threshold, the dosage was too high and that when the blood concentration was below a lower threshold, the dosage was too low. No one needed to do anything with this information to infringe the claims. This suggests that adding an affirmative treatment step to your patent claims may provide a work around for Prometheus.
Limiting claims to require a treatment step has its drawbacks. Competitor testing labs would not perform a treatment step and could not directly infringe a claim that requires one. However, if the claims are written so that all steps are performed by the physician or hospital, the testing lab could potentially be liable for inducing infringement by the physician or hospital. That said, the Prometheus decision suggests that the Supreme Court would likely find claims with a treatment step invalid unless the treatment process is new. So, it is unclear if such claims would survive Supreme Court scrutiny. However, it will be interesting to see how the U.S. Patent & Trademark Office and the Federal Circuit apply the Prometheus holding and whether they attempt to limit it to the facts and claim language that were at issue in the case.
For now, what we can say is that if the testing method includes new steps and does not merely use old techniques to determine if the concentration of an analyte is within a certain window or if a genetic marker is present, the method may be patentable even under the Prometheus framework. However, it may be difficult to obtain enforceable patents if the test methods themselves and the treatment methods are known but merely apply a newly discovered "physical phenomenon" or "law of nature."