CytomX Announces the First Patient Treated in Phase 1/2 PROCLAIM-072 Trial

SOUTH SAN FRANCISCO, Calif., Feb. 02, 2017 -- CytomX Therapeutics, Inc. (Nasdaq:CTMX), a biopharmaceutical company developing investigational Probody™ therapeutics for the treatment of cancer, today announced the treatment of the first patient in the PROCLAIM (Probody Clinical Assessment In Man) CX-072 study, a Phase 1/2 clinical trial evaluating CX-072, a PD-L1-targeting Probody therapeutic, as monotherapy and in combination with Yervoy^® (ipilimumab) or Zelboraf^®(vemurafenib) in patients with all types of cancers.

“Treating the first patient with CX-072 marks a key milestone as we advance our broad pipeline of innovative Probody therapeutics into clinical development within the PROCLAIM program,” said Rachel W. Humphrey, M.D., chief medical officer of CytomX Therapeutics. “Advancement of this potentially transformational treatment, derived from our Probody technology platform, would not be possible without the patients who are willing to engage with the scientific community by enrolling in clinical trials. We thank them for their participation.”

About the PROCLAIM-072 Trial
The first clinical trial under the international umbrella program PROCLAIM is the open-label, dose-finding Phase 1/2 study evaluating CX-072 as monotherapy and in combination with Yervoy^® (ipilimumab) or Zelboraf^®(vemurafenib) in patients with all types of cancers. As part of the study, CytomX aims to achieve three goals as part of the PROCLAIM-072 clinical trial:

• Tolerability: Demonstrate that CX-072 is well tolerated in patients and potentially improves safety, particularly in the combination setting.
• Anti-cancer activity: Demonstrate initial evidence of CX-072’s anti-cancer activity as monotherapy and in combination.
• Translational program and Probody platform proof-of-concept: Explore mechanistic aspects of Probody activity in patients as observed in preclinical studies.

More information about the trial is available at clinicaltrials.gov.

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 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.  The company’s investigational Probody therapeutics address clinically-validated cancer targets in immuno-oncology, such as PD-L1, against which the 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. In addition to its proprietary programs, CytomX is collaborating with strategic partners including AbbVie, 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 beginning clinical development, and the process by which clinical development could potentially lead to an approved product is long and subject to significant risks and uncertainties. Projected net cash utilization and capital resources are subject to substantial risk of variance based on a wide variety of factors that can be difficult to predict.  Applicable risks and uncertainties include those relating to our preclinical research and development, clinical 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.

Corporate Communications Contact: 
Canale Communications
Ian Stone
[email protected]
619-849-5388

Investor Contact:
Trout Group
Pete Rahmer
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646-378-2973