OSAKA--Shionogi & Co., Ltd. has completed an initial analysis of the results from a Phase IIa Proof of Concept (POC) study of S-5751 in asthma patients, which was conducted in both the U.S.A. and Europe. The results demonstrate that S-5751, a prostaglandin D2 (PGD2) receptor antagonist, did not meet the primary endpoint. Therefore, Shionogi has decided to terminate the development of this compound.

For the POC study, approximately 400 asthma patients were recruited and randomly divided into three groups of high and low doses of S-5751 and placebo. Clinical efficacy for asthma patients was evaluated using FEV1.0 (Forced Expiratory Volume in one second), which was designated as a primary endpoint of the study. During the study period, patients were not allowed to use or take any products containing steroid hormones.

Study result from both high and low dose groups of S-5751, however, did not show any statistical significance compared with that from the placebo group. Thus, Shionogi has decided to discontinue further development of this compound.

Shionogi continues its strong commitment to promoting research in the PGD2 field by expediting the evaluation of backup candidates that have already been identified, while conducting more detailed statistical analysis of the current study.