CytomX, a biotechnology company developing Probody™ therapeutics for the treatment of cancer, today announced that the company has raised $20 million in a Series C financing round. Pfizer Venture Investments led the round, with participation from existing investors Third Rock Ventures, Canaan Partners and the Roche Venture Fund.

'CytomX continues to make significant progress with our Probody platform, and that effort has resulted in a compelling pipeline of wholly owned and partnered Probody therapeutics,' said Sean McCarthy, D. Phil., chief executive officer of CytomX. 'The proceeds from this financing will help enable CytomX to advance our proprietary pipeline of Probody Drug Conjugates and Probodies against cancer immunotherapy checkpoint targets towards the clinic, while we also pursue Probody applications with bispecific antibodies and engineered T-cell therapies. We have enjoyed a productive strategic partnership with Pfizer Inc. since June 2013 in the drug conjugate space, and we look forward to continuing to build on this relationship by welcoming Pfizer Venture Investments to our investor syndicate.'

Probodies are fully recombinant, masked antibodies that remain inert in healthy tissue but are activated specifically in the tumor microenvironment. Through this precise targeting of the diseased tissue, Probodies can localize activity to the tumor microenvironment, opening up therapeutic window and enabling development of potent therapeutics against novel targets. CytomX is developing a pipeline of Probody therapeutics against novel and validated drug conjugate and cancer immunotherapy targets. In addition to focusing on its internal pipeline, CytomX is developing Probody therapeutics in partnership with Pfizer, Immunogen, and Bristol-Myers Squibb.

Elaine Jones, Ph.D., executive director of Venture Capital at Pfizer Venture Investments, will join CytomX's board of directors as of January 15, 2015.

'Cytomx's platform provides an important advance for both antibodies and antibody-drug conjugates, enabling the potential development of novel therapeutics against a broader number of targets while minimizing the possibility for on-target toxicity,' said Dr. Jones. 'Since signing a collaboration with CytomX in 2013, Pfizer has been impressed with the Probody platform. We are pleased to lead this Series C investment and support the company's efforts in developing its wholly owned pipeline.'

About CytomX Therapeutics
CytomX Therapeutics is a biotechnology company developing Probody™ therapeutics for the treatment of cancer. Probodies are masked antibodies that remain inert in healthy tissue but are activated specifically in the disease microenvironment. The Probody approach is designed to blunt systemic toxicities associated with antibodies and expand the therapeutic window of these drugs, unlocking new therapeutic targets. The Company is initially focusing this highly innovative platform to discover and develop new immunotherapy and antibody drug conjugate therapies to treat areas of major unmet medical need in oncology. CytomX has attracted multiple strategic collaborations with industry-leading pharmaceutical companies including Pfizer Inc., ImmunoGen and Bristol-Myers Squibb. CytomX is led by a seasoned and proven management team and is financed by leading life science investors, including Pfizer Venture Investments, Third Rock Ventures, Canaan Partners and the Roche Venture Fund. For more information, please visit www.cytomx.com.

About Pfizer Venture Investments
Pfizer Venture Investments (PVI), the venture capital arm of Pfizer Inc., was founded in 2004 and invests for return in areas of current or future strategic interest to Pfizer. As part of the Worldwide Business Development division, PVI seeks to remain at the forefront of life science advances, looking to identify and invest in emerging companies that are developing compounds and technologies that have the potential to enhance Pfizer's pipeline and shape the future of our industry. For more information, please visit www.pfizerventureinvestments.com.