Celldex Therapeutics, Inc. (NASDAQ: CLDX) today announced that the first patient has been treated in a randomized Phase 2b study of the Company’s CDX-011 (glembatumumab vedotin) antibody drug conjugate in glycoprotein NMB (GPNMB) expressing advanced, refractory breast cancer patients. CDX-011 targets the protein GPNMB, which is over expressed in a variety of cancers including breast cancer, melanoma, and brain tumors.

“The CDX-011 antibody drug conjugate provides a targeted intervention for GPNMB expressing breast cancer, including patients with triple-negative disease” said Tom Davis, MD, Chief Medical Officer of Celldex Therapeutics, Inc. “This Phase 2b trial will target patients whose tumors express GPNMB and is anticipated to include a significant proportion of patients with difficult-to-treat triple-negative tumors. It will build upon the positive Phase 1/2 trial which demonstrated encouraging activity in both of these patient subsets.”

The study is a randomized, multi-center, controlled trial that will enroll 120 patients with heavily pre-treated, advanced breast cancer who are unlikely to benefit from any approved therapies and whose tumors are confirmed to express GPNMB via a validated, centralized diagnostic assay. It is anticipated that a significant portion of the enrolled patients will have triple-negative disease, since GPNMB is frequently expressed in this patient population. Patients will be randomized (2:1) to receive either CDX-011 or single-agent “Investigator’s Choice” chemotherapy. Activity endpoints will include response rate, progression-free survival (PFS) and overall survival (OS). The study will be conducted in approximately 25 academic and community sites across the U.S. Preliminary results are expected in Q4 2011.

In May, the U.S Food and Drug Administration (FDA) granted Fast Track designation to CDX-011 for the treatment of advanced, refractory or resistant GPNMB-expressing breast cancer.

About Breast Cancer

Breast cancer is the most common cancer in women and a leading cause of death in the United States. According to the American Cancer Society, more than 180,000 women will be diagnosed with invasive breast cancer in 2009 with more than 40,000 deaths attributed to this disease. Despite recent advances in therapy, the median survival of patients with metastatic breast cancer is 2 to 3 years, while patients with "triple-negative" or "basal-like" breast cancer have limited treatment options due to lack of over-expression of HER2, estrogen and progesterone receptors and poorer outcomes. Therefore, a significant unmet need remains for novel therapeutic approaches for patients with locally advanced and metastatic breast cancer who have failed other therapies.

About CDX-011

CDX-011 (glembatumumab vedotin) is an antibody-drug conjugate (ADC) that consists of a fully-human monoclonal antibody, CR011, linked to a potent cell-killing drug, monomethyl-auristatin E (MMAE). The ADC technology, comprised of MMAE and a stable linker system for attaching it to CR011, was licensed from Seattle Genetics, Inc. The ADC is designed to be stable in the bloodstream. Following intravenous administration, CDX-011 targets and binds to GPNMB, a specific protein that is expressed in at least 40% of breast cancers as well as other tumor types, and which promotes the migration, invasion, and metastasis of breast cancer. Upon internalization into the targeted cell, CDX-011 is designed to release MMAE from CR011 to produce a cell-killing effect. CDX-011 has been shown to be safe and active, with observed objective responses, in two positive Phase 1/2 trials in metastatic breast cancer and advanced melanoma. In May 2010, the U.S Food and Drug Administration (FDA) granted Fast Track designation to Celldex’s CDX-011 for the treatment of advanced, refractory/resistant GPNMB-expressing breast cancer.

About Celldex Therapeutics, Inc.

Celldex Therapeutics is the first antibody-based combination immunotherapy company. Celldex has a pipeline of drug candidates in development for the treatment of cancer and other difficult-to-treat diseases based on its antibody focused Precision Targeted Immunotherapy Platform. The PTI Platform is a complementary portfolio of monoclonal antibodies, antibody-targeted vaccines and immunomodulators used in optimal combinations to create novel disease-specific drug candidates. For more information, please visit http://www.celldextherapeutics.com.

Safe Harbor Statement Under the Private Securities Litigation Reform Act of 1995: This release contains “forward-looking statements” made pursuant to the safe harbor provisions of the Private Securities Litigation Reform Act of 1995, including those related to the Company’s strategic focus and the future development and commercialization (by Celldex and others) of rindopepimut (CDX-110), CDX-1307, CDX-011, CDX-1135 (formerly TP10), CDX-1401, Belinostat, Rotarix® and other products. Forward-looking statements reflect management's current knowledge, assumptions, judgment and expectations regarding future performance or events. Although management believes that the expectations reflected in such statements are reasonable, they give no assurance that such expectations will prove to be correct and you should be aware that actual results could differ materially from those contained in the forward-looking statements. Forward-looking statements are subject to a number of risks and uncertainties, including, but not limited to, our ability to obtain additional capital on acceptable terms, or at all; our ability to adapt APC Targeting TechnologyTM to develop new, safe and effective vaccines against oncology and infectious disease indications; our ability to successfully complete product research and further development of our programs; our development partners’ willingness to make announcements with respect to co-developed products; the uncertainties inherent in clinical testing; our ability to manage research and development efforts for multiple products at varying stages of development; Pfizer’s and our strategy and business plans concerning the continued development and commercialization of rindopepimut (CDX-110); the uncertainties of any future payments with respect to Belinostat, as the development and commercialization of Belinostat is completely outside of Celldex's control; the uncertainties of any future royalty payments with respect to Rotarix®, as the commercialization of Rotarix® is completely outside of Celldex's control; the timing, cost and uncertainty of obtaining regulatory approvals; the failure of the market for the Company's programs to continue to develop; our ability to protect the Company’s intellectual property; the loss of any executive officers or key personnel or consultants; our ability to successfully integrate the businesses, multiple technologies and programs of CuraGen and Celldex; competition; changes in the regulatory landscape or the imposition of regulations that affect the Company’s products; and other factors listed under “Risk Factors” in our annual report on Form 10-K.

All forward-looking statements are expressly qualified in their entirety by this cautionary notice. You are cautioned not to place undue reliance on any forward-looking statements, which speak only as of the date of this release. We have no obligation, and expressly disclaim any obligation, to update, revise or correct any of the forward-looking statements, whether as a result of new information, future events or otherwise.