SR-16234

SR-16234 is a selective estrogen receptor modulator (SERM) structurally different from approved SERM and has been reported to have estrogen receptor (ER) α antagonistic activity and strong affinity with a weak partial agonistic activity to ERβ receptor. SR-16234 showed strong inhibitory effects on transplanted endometrial cysts in the endometriosis model of rat and mouse. In this clinical trial, efficacy and safety of SR-16234 have been evaluated in endometriosis patients.

This trial was an open-label single arm clinical trial. Ten patients with dysmenorrhea and pelvic pain associated with endometriosis and adenomyosis were enrolled in this trial, and received 40 mg of SR-16234 once daily for 12 weeks. The primary endpoint was the visual analogue scale (VAS) of pelvic pain. The secondary endpoints included dysmenorrhea score, pelvic pain score, objective observations (stiffness of Douglas' pouch, limitation of uterine movement, size of ovarian chocolate cysts, thickness of endometrium, and serum CA125 concentration) and safety.

After oral administration of SR-16234 40 mg for 12 weeks, there were statistically significant decreases in pelvic pain VAS, total pelvic pain score, total dysmenorrhea score, stiffness of Douglas' pouch, limitation of uterine movement compared with the baseline values.

The present trial suggested that a selective estrogen receptor modulator could be used for treatment of pain associated with endometriosis for the first time.

The increasing cost of drug research and development and the decreasing number of new drugs being launched are serious issues for pharmaceutical companies. Biomarkers for predicting drug effectiveness are regarded as useful tools for combating these trends. However, the extent to which these biomarkers actually help in improving drug development is unclear. Here, we investigated the efficiency of biomarker usage in oncology drug development by focusing on stratification markers.

Anti-tumour agents for which clinical studies were initiated between 1998 and 2009 were identified using commercially available data sources, and clinical trials registered in ClinicalTrials.gov were examined to identify the use of stratification marker. Phase transition probability for each clinical phase was calculated and analysed along with various other factors that may affect the efficiency of the development process.

Of 908 anti-tumour agents identified, 121 (13·3%) utilized stratification markers in their clinical studies. Phase I, II and III transition probabilities for all agents were 76·4%, 50·8% and 58·5%, respectively. Corresponding Phase I, II and III transition probabilities of agents developed with stratification markers of 90·4%, 69·0% and 85·0%, respectively, were significantly higher than those for agents without stratification markers. Orphan designation positively affected phase transition probabilities of agents without stratification markers in all phases, while it did not affect transition probabilities of agents with stratification markers, except for Phase II. This shows that stratification markers help improve the probability of success in the development of agents without orphan designation.

Stratification markers contribute to improving the efficiency of development of anti-cancer drugs. The majority of non-orphan drugs are still being developed without stratification markers. Finding reliable stratification markers for all drugs should improve the success rates in drug development.