Quintessence Biosciences: Presents human ribonuclease variant, QBI-139, at the American Society of Clinical Oncology meeting

Contact: Dr. Laura Strong, President and Chief Operating Officer, 608-441-2950

CHICAGO, IL AND MADISON, WI – Quintessence today announced that data for their lead EVade™ Ribonuclease, called QBI-139, will be presented at the American Society of Clinical Oncology 46th Annual Meeting. QBI-139 is a protein therapeutic that targets the RNA in cancer cells. The data from abstract TPS162 will be presented at 8 AM on Monday June 7, 2010. The focus will be on the design of the Phase I clinical trial of QBI-139. QBI-139 has shown broad single agent activity against a variety of cancer models addressing significant unmet need, such as non-small cell lung and pancreatic cancers.

About Quintessence Biosciences, Inc.

Quintessence Biosciences, Inc. is a private biopharmaceutical company focused on development of cancer therapies based on the proprietary EVade™ Ribonuclease technology. Quintessence’s first product candidate, QBI- 139, is in a Phase 1 clinical trial at The University of Texas M.D. Anderson Cancer Center and The University of Wisconsin Carbone Cancer Center. The company also has a pipeline of other EVade™ Ribonuclease products in preclinical research. For more information, visit http://www.quintbio.com.

About the American Society of Clinical Oncology

The 46th Annual Meeting of the American Society of Clinical Oncology (ASCO) is being held in Chicago, June 4-8, 2010. This year’s Annual Meeting will focus on Advancing Quality through Innovation. More than 30,000 cancer specialists from around the world will gather to discuss the latest innovations in research, quality, practice and technology in cancer. For more information, visit http://chicago2010.asco.org/Home.aspx

About the ASCO Annual Meeting Trials in Progress Poster Session

The objective of the Trials in Progress Poster Session is to publicize ongoing phase I or phase II trials and stimulate discussion and participation among peers. The posters discuss the science behind the trial, including pre-clinical data. In addition, the posters will describe the trial design and current enrollment status.