Sosei Announces Results of AD 452 Phase IIb Clinical Trial TOKYO, Japan, November 21 -- Sosei Group Corporation ("Sosei"; TSE Mothers Index: 4565), the biopharmaceutical company, today announced that AD 452, being developed for the treatment of rheumatoid arthritis (RA), failed to meet its primary or secondary efficacy endpoints in the company's Phase IIb clinical trial. As a consequence of these results Sosei has decided to discontinue with the development of this compound for the treatment of RA and remove AD 452 from its priority pipeline. The trial randomized 308 subjects at 35 sites in Europe and the US into a multi-centre, double-blind, parallel group, placebo controlled study to assess the efficacy, safety and tolerability of three strengths of AD 452 administered once daily for 12 weeks to adult subjects with active RA despite a background therapy of methotrexate. The primary efficacy endpoint was ACR20 at week 12. At 12 weeks in the AD 452 treatment groups, 36% with a 9mg dose, 40% with 18mg and 40% with the top dose of 36mg had achieved ACR20 compared to 32% in the placebo with methotrexate background group. There was no statistically significant difference between the treatment groups and placebo. The trial confirmed that AD 452 has a good safety profile. Notes to Editors: Efficacy measurement ACR20 ACR20 is a recognised measurement of the response to treatment for rheumatoid arthritis as developed by the American College of Rheumatology. To achieve ACR20 there should be a 20% reduction in tender and swollen joints and a 20% reduction in 3 out of 5 of the following tests: physician global score, patient global score, patient pain assessment, health assessment questionnaire and an inflammatory marker. About Sosei Sosei Co. Ltd. is a leading international biopharmaceutical company with significant expertise in product discovery and development. It has established a reduced risk business model primarily upon identifying new uses for established drugs and exploiting its unique position within Japanese, European and North American pharmaceutical markets by acquiring compounds from, and bringing compounds into, Japan.