Study Finds That New Laboratory Tests From Prometheus Laboratories May Enable Doctors to Individualize Rheumatoid Arthritis Therapy SAN DIEGO, Oct. 27 /PRNewswire/ -- New data presented at the 67th Annual American College of Rheumatology (ACR) Scientific Meeting shows that a patient's long-chain methotrexate polyglutamate level may be a better indicator of clinical response than actual drug dose in rheumatoid arthritis patients on methotrexate therapy. Methotrexate polyglutamate levels were measured utilizing a new laboratory test, TREXSCORE(SM) developed by Prometheus Laboratories Inc. and planned for release in early 2004. (Logo: http://www.newscom.com/cgi-bin/prnh/20030416/PROMETHEUSLOGO ) The data presented were collected from a study of 114 patients with rheumatoid arthritis. In the study, patients with a long-chain methotrexate polyglutamate level above a certain threshold were found to be 14 times more likely to have a good clinical response than patients with lower levels. In the study, patient drug dosage had a limited correlation to response. These results suggest that physicians could use the TREXSCORE test to better tailor individual therapy in their patients. The Arthritis Foundation estimates that rheumatoid arthritis affects one percent of the U.S. adult population, approximately 2.1 million patients. Approximately forty-percent of rheumatoid arthritis patients take a therapeutic regimen that includes methotrexate, making it one of the most frequently prescribed disease modifying anti-rheumatic drugs. The current treatment approach of "start low and go slow" often results in sub-optimal methotrexate dosing and highlights the unmet clinical need to identify a better indicator of therapeutic response in patients with rheumatoid arthritis on methotrexate therapy. "Rheumatologists trust methotrexate as the standard of care in rheumatoid arthritis," said Dr. Joel M. Kremer, Director of Research at The Center for Rheumatology in Albany, New York. "Rheumatologists are looking for ways to better understand methotrexate therapy, and a therapy monitoring test could offer some help in understanding response." ACR Scientific Presentations Prometheus Laboratories has three abstracts relating to this breakthrough study presented at the ACR Annual Scientific Meeting in Orlando, Florida from October 23 to October 28, 2003. The abstracts include the following oral and poster presentations: Oral Presentation: * Single Nucleotide Polymorphisms (SNPs) in the Folate/Purine Synthesis Pathway Predict Methotrexate's Effects in Rheumatoid Arthritis. Thierry Dervieux(1), Diana Orentas Lein(1), Grace Park(2), John Marcelletti(1), Gary Meyer(1), Katie Smith(1), Michael Walsh(1), Daniel Furst(2), Joel Kremer(3) Poster Presentations: * Methotrexate Polyglutamate Concentrations in Red Blood Cells Correlates with Disease Activity and Clinical Response to Methotrexate in Rheumatoid Arthritis. Thierry Dervieux(1), Diana Orentas Lein(1), Grace Park(2), John Marcelletti(1), Gary Meyer(1), Katie Smith(1), Michael Walsh(1), Joel Kremer(3), Daniel Furst(2) * Responder Phenotype and Disease Activity of Rheumatoid Arthritis (RA) Patients Receiving Methotrexate (MTX) Are Correlated with Levels of Soluble CD26 and CD30. John F. Marcelletti(1), Diana Orentas Lein(1), Lynn Simpson(1), Jason Do(1), Michael J. Walsh(1) (1) Prometheus Laboratories Inc., San Diego, CA (2) UCLA Geffen School of Medicine, Los Angeles, CA (3) The Center for Rheumatology, Albany, NY Data Results In the observational study, blood samples were collected from 114 patients between two and seven days following their last dose of methotrexate. Patients enrolled had active rheumatoid arthritis and must have been on a steady dose of methotrexate, without any additional disease-modifying rheumatoid arthritis drugs for at least thirty days. Data was collected including information regarding tender and swollen joints, DAS 28 (using a commonly used subset of 22 joints), and several patient and physician global assessments. Results showed higher long-chain methotrexate polyglutamate levels (>60 nmol/L) in patients who scored better in the physician's global assessment of disease activity (R=-0.30, p=0.001), number of swollen joints (R=-0.20, p=0.03), and physician assessment of response to methotrexate (R=-0.034, p=0.003). There was limited correlation between drug dose levels and response to therapy. For more information about the TREXSCORE laboratory test, visit the new website, http://www.methotrexatedx.com/ . About Prometheus Laboratories Prometheus Laboratories Inc. is a specialty pharmaceutical company committed to developing new ways to help physicians individualize patient care. Prometheus focuses on the treatment, diagnosis and detection of gastrointestinal, autoimmune and inflammatory diseases and disorders. Prometheus' strategy includes the marketing and delivery of pharmaceutical products complemented by its proprietary, high-value diagnostic testing services. By integrating therapeutics and diagnostic services, Prometheus addresses the continuum of patient care, thereby providing physicians with a comprehensive solution to treat chronic diseases. Prometheus' corporate offices are located in San Diego, California. Additional information about Prometheus Laboratories can be found at http://www.prometheuslabs.com/ . Contact: Prometheus Laboratories Inc. Beth Kriegel Senior Director, Corporate Communications and Investor Relations 858/410-2516 http://www.newscom.com/cgi-bin/prnh/20030416/PROMETHEUSLOGO http://photoarchive.ap.org/ DATASOURCE: Prometheus Laboratories Inc. CONTACT: Beth Kriegel, Senior Director, Corporate Communications and Investor Relations of Prometheus Laboratories Inc., +1-858-410-2516 Web site: http://www.methotrexatedx.com/ Web site: http://www.prometheuslabs.com/

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