Thiopurine drugs such as 6-mercaptopurine are used as chemotherapeutic agents and immunosuppressive drugs.

TPMT is best known for its role in the metabolism of the thiopurine drugs such as azathioprine, 6-mercaptopurine and 6-thioguanine.

The debate between the two companies is based on a certain diagnostic test, specifically concerning the use of thiopurine drugs, which are used to treat autoimmune diseases.

Prometheus’s test involves the optimal dosage of thiopurine drugs, which are used for all sorts of ailments, including Crohn’s disease, some skin diseases and lupus.

The patents concern the use of thiopurine drugs in the treatment of autoimmune diseases, such as Crohn's disease and ulcerative colitis.

TPMT catalyzes the S-methylation of thiopurine drugs.

Inheriting abnormal thiopurine S-methyltransferase may affect the metabolism of the thiopurine drugs mercaptopurine and azathioprine.

TPMT metabolizes 6-mercaptopurine and azathioprine, two thiopurine drugs used in a range of indications, from childhood leukemia to autoimmune diseases.

The problem with thiopurine drugs is that different patients metabolize them differently, which causes difficulty in determining whether a patient's dosage is too high or too low.

Measurement of TPMT activity is encouraged prior to commencing the treatment of patients with thiopurine drugs such as azathioprine, 6-mercaptopurine and 6-thioguanine.

The thiopurine drugs are purine antimetabolites widely used in the treatment of acute lymphoblastic leukemia, autoimmune disorders (e.g., Crohn's disease, rheumatoid arthritis), and organ transplant recipients.

 "The results of this pilot project could help provide evidence supporting the clinical value and cost effectiveness of the routine use of this testing in patients taking thiopurine drugs."

Thiopurine drugs -- immunosuppressive medicines that inhibit the body's immune system -- are regularly used to treat inflammatory bowel disease, the researchers said, but can increase the risk of cancers linked to viral infections.

Pharmacogenomic strategies have recently been shown to reduce the risk of toxicity of thiopurine drugs, while drug metabolite measurement can enhance response rates using azathioprine and 6-mercaptopurine for IBD and rheumatological disorders.

Prometheus had a patent on how to properly treat patients using thiopurine drugs that included an administering step in which a doctor would administer the drug to the patient, a determining step in which the doctor measures the metabolite levels in the patient's blood, and a step to either increase or decrease the dosage based on the results.