CTCs are the cancer cells that are found to be in the bloodstream, detached from a solid tumor in the body.

The diagnostic will help to treat patients with anti-progestins including onapristone, an orally-administered, investigational type 1 progestin receptor antagonist that is being developed by Arno.

Arno CEO and president Glenn Mattes said, "By taking blood samples from patients rather than obtaining tissue samples, we hope to create a simplified and less invasive process for identifying patients that are most likely to benefit from treatment with onapristone."

The partnership permits Arno to use Veridex’s Cellsearch technology that uses microfluidic separation, an advanced cell separation technique.

Microfluidic separation is integrated with the magnetic sorting to isolate CTCs and to further analyze the cells for the presence of APR.

The Cellsearch CTC System is the only standardized semi-automated system that captures, isolates, and counts CTCs with a high level of sensitivity and specificity.

Onapristone works by binding to progesterone receptor proteins, thereby inhibiting dimerization, phosphorylation and DNA transcription activity.

Preclinical studies have shown that progesterone receptor cells have a role as the drivers of malignant cell growth in certain cancers.