Supreme Court's Ruling against Prometheus Shakes Up Personalized Medicine

The Supreme Court's unanimous ruling last month that a Prometheus Laboratories' patents on a blood test that looks at variations of a particular gene to determine an individual's dosage for a particular drug were not valid created somewhat of a sensation in the biotech sphere. Prometheus, part of Nestle Health Science, sued the Mayo Clinic when the clinic substituted its own in-house developed procedure for the $260 test that Prometheus sold to determine a patient's starting dose of the drug thiopurine, which is often used to treat inflammatory bowel diseases such as Crohn's disease or ulcerative colitis. Prometheus lost and the Court invalidated claims in two of its patents in a ruling that rippled in companies involved with personalized medicine.

The diagnostic test at the center of the dispute uses HPLC to identify variations of the gene thiopurine methyltransferase (TPMT). Different variants of TPMT metabolize the drug at different rates so a doctor can infer which dosage of the drug to give a patient by identifying which genetic variation of TPMT that a patient has. The Supreme Court sided with the original ruling of the local district court that the test was unpatentable because it is an observation of a natural correlation between the gene and the metabolism rate of the drug.  In other words, the Court felt it is simply an observation not a patentable invention.

As evidenced by the range of coverage in biotech trade publications (e.g., GEN , GenomeWeb, The Scientist, and ScienceInsider), the ruling certainly stimulated significant discussion. At issue, it creates a lot of uncertainty for companies trying to protect their right to commercialize discoveries that relate clinical treatments with specific genetic variations. This the basis of emerging personalized medicine approaches.