Singapore: Arno Therapeutics, a US-based clinical-stage biopharmaceutical company focused on the development of oncology therapeutics, has identified a new immunohistochemistry technique for identifying activated progesterone receptors in breast cancer tumors that may be predictive of response to treatment with onapristone.

Onapristonean is an investigational progestin receptor antagonist that is being developed by Arno and has demonstrated anti-tumor activity in preclinical and clinical studies.

Researchers have evaluated new technique for identifying the activated form of the progesterone receptor via nuclear morphology that can be done on a routine basis with freshly obtained or paraffin-fixed and paraffin-embedded tissue. The technique is being further refined and tested on a larger cohort of breast and endometrial cancer samples, with correlation to other standard tumor markers and clinical outcomes.

The investigators believe that this technique for identifying activated progesterone receptors may allow a method for selecting patients, who are most likely to respond to antiprogestins such as onapristone.

Mr Glenn Mattes, president and chief executive officer, Arno Therapeutics, stated that, "The continued progress of our research colleagues in describing the predictive value of activated progesterone receptors suggests that we are moving closer to identifying a clinical biomarker that may determine which patients with breast, endometrial and other cancers respond best to treatment with onapristone. This work is very helpful to our efforts to develop a companion diagnostic for onapristone, which is an integral part of our clinical development of onapristone as a potential new cancer therapy."