In Mayo Collaborative Services v. Prometheus Laboratories, Inc., the Supreme Court of the United States held unanimously that claims directed to a method of altering a drug dose based on levels of the drug’s metabolite are ineligible for patent protection under section 101 of the patent statute. In doing so, the Court departed from its long-standing precedent that section 101 of the patent statute should be interpreted broadly in favor of patent eligibility. The Supreme Court further appears to have conflated 35 U.S.C. §§ 102, which requires patent claims to be novel, and 103, requiring claims to be nonobvious, into the patent eligibility analysis under § 101.

Background

Prometheus is the exclusive licensee of U.S. Patent Nos. 6,355,623 and 6,680,302 directed to processes for using thiopurine drugs to treat autoimmune diseases such as Crohn’s disease and ulcerative colitis. Upon ingestion, thiopurines are metabolized and introduced into the bloodstream. Because individual patients metabolize thiopurines differently, it is difficult for doctors to determine whether a particular dosage is too high—risking harmful side effects—or too low—and ineffective—for a particular patient. The patent claims at issue set forth processes which identify correlations between thiopurine levels in a patient’s bloodstream and a target range, allowing a doctor to optimize thiopurine dosages for individual patients.