CytomX Selects Probody Drug Conjugate Clinical Candidate, CX-2009, Targeting Highly Expressed Tumor Antigen, CD166

SOUTH SAN FRANCISCO, Calif., Dec. 11, 2015 (GLOBE NEWSWIRE) -- CytomX Therapeutics, Inc. (Nasdaq:CTMX), a biopharmaceutical company developing investigational Probody™ therapeutics for the treatment of cancer, today announced that it has selected its second clinical candidate from its Probody therapeutic pipeline. The candidate, CX-2009, is a first-in-class Probody drug conjugate targeting CD166. CX-2009 utilizes ImmunoGen, Inc. conjugate technology.

"CD166 is highly and homogeneously expressed in the majority of patients with a variety of solid tumors," said Michael Kavanaugh, M.D., chief scientific officer. "Despite high expression of CD166 in normal tissues, our Probody technology is designed to concentrate CX-2009 only in tumor tissue. As such, we believe that CX-2009 is uniquely positioned to deliver on the promise of CD166 as a target. We look forward to testing CX-2009 in patients and are on track to file the IND in 2017."

In October, CytomX researchers presented preclinical safety and efficacy data for the CD166 Probody drug conjugate program at the AACR-NCI-EORTC International Conference on Molecular Targets. The data showed that CytomX's CD166-directed Probody drug conjugates were efficacious in xenograft tumor models at doses equal to or below the predicted human dose. The therapeutics were also well-tolerated in preclinical studies at a dose predicted to be therapeutically relevant.

Therapeutics developed with CytomX's Probody platform are designed to be active in the tumor while sparing healthy tissue. By restricting activity to the tumor microenvironment, Probody therapeutics directed against both validated and novel targets have been shown pre-clinically to enable anti-tumor efficacy with a significantly enhanced safety window, relative to traditional antibody-based therapies. CytomX's preclinical pipeline of wholly-owned and partnered programs includes Probody cancer immunotherapies, Probody drug conjugates and T-cell engaging Probody bispecifics.

About CytomX Therapeutics

CytomX is an oncology-focused biopharmaceutical company pioneering a novel class of investigational antibody therapeutics based on its Probody technology platform. The company uses the platform to create development-stage proprietary cancer immunotherapies against clinically-validated targets, as well as to develop first-in-class investigational cancer therapeutics against novel targets. CytomX believes that its Probody platform has the potential to improve the combined efficacy and safety profile of monoclonal antibody modalities, including cancer immunotherapies, antibody drug conjugates and T-cell-recruiting bispecific antibodies. Probody therapeutics are designed to take advantage of unique conditions in the tumor microenvironment to enhance the tumor-targeting features of an antibody and reduce drug activity in healthy tissues. Investigational Probody therapeutics are being developed that address clinically-validated cancer targets in immuno-oncology, such as PD-L1 against which our clinical candidate CX-072 is directed, as well as novel targets, such as CD-166, that are difficult to drug without causing damage to healthy tissues, or toxicities. In addition to its proprietary programs, CytomX is collaborating with strategic partners including Bristol-Myers Squibb Company, Pfizer Inc., MD Anderson Cancer Center, and ImmunoGen, Inc. For more information, visit www.cytomx.com.

Forward-Looking Statements

This press release includes forward-looking statements. Such forward-looking statements involve known and unknown risks, uncertainties and other important factors that are difficult to predict, may be beyond our control, and may cause the actual results, performance or achievements to be materially different from any future results, performance or achievements expressed or implied in such statements. Accordingly, you should not rely on any of these forward-looking statements. Our Probody platform is in preclinical development, and the process by which a preclinical technology could potentially lead to an approved product is long and subject to significant risks and uncertainties. Applicable risks and uncertainties include those relating to our preclinical research and development and other risks identified under the heading "Risk Factors" included in our filings with the SEC. The forward-looking statements contained in this press release are based on information currently available to CytomX and speak only as of the date on which they are made. CytomX does not undertake and specifically disclaims any obligation to update any forward-looking statements, whether as a result of any new information, future events, changed circumstances or otherwise.

CONTACT: Corporate Communications Contact:
         Canale Communications
         Ian Stone
         [email protected]
         619-849-5388
         
         Investor Contact:
         Trout Group
         Pete Rahmer
         [email protected]
         646-378-2973