Celldex Therapeutics, Inc. (Nasdaq: CLDX) today announced initiation of a Phase 1 study of its therapeutic human antibody candidate, CDX-1127, in patients with selected malignant solid tumors or hematologic cancers. CDX-1127 is a fully human monoclonal antibody that binds CD27, an important co-stimulatory molecule on T cells. CDX-1127, an agonist antibody designed to activate patients’ immune cells against their cancer, has shown potent efficacy in several preclinical models. In addition, CD27 is over-expressed in certain lymphomas and leukemias and can be directly targeted by CDX-1127.

The Phase 1 study is designed to test 5 escalating doses of CDX-1127 to determine a Phase 2 dose for further development based on safety, tolerability, potential activity and immunogenicity. The study will accrue approximately 30 patients in each of the two arms, either solid tumors or lymphomas/leukemias. Patients will have received all appropriate prior therapies for their specific disease. The trial design incorporates both single dosing and multiple dosing regimens at each dose level. The study, anticipated to complete accrual in approximately 1 year, is being conducted at multiple clinical sites in the United States.

“The CDX-1127 program is our first therapeutic antibody and demonstrates our development capabilities to rapidly and successfully translate concept into clinical trials,” said Anthony S. Marucci, President and Chief Executive Officer of Celldex Therapeutics. “We believe strongly in the opportunities for immune modulating antibodies and the pre-clinical data generated with CDX-1127 through our collaboration with University of Southampton, UK has been very encouraging.”

About CDX-1127

CDX-1127 is a human monoclonal antibody program targeting CD27, a member of the tumor necrosis factor (TNF) receptor superfamily. CD27 is a critical molecule in the activation pathway of lymphocytes.

It acts downstream from CD40 and may provide a novel way to regulate the immune responses. CD27 is a co-stimulatory molecule on T cells and is over-expressed in certain lymphomas and leukemias. Previously published data by Professor Martin Glennie, Ph.D., Director of Cancer Sciences, Tenovus Research Laboratory, University of Southampton, UK, has demonstrated that targeting CD27 with monoclonal antibodies in mice is highly effective at promoting anti-cancer immunity. Celldex presented more recent preclinical in vitro and animal data with CDX-1127 at the 2011 American Association for Cancer Research (AACR) 101st Annual Meeting demonstrating that targeting CD27 receptors with CDX-1127 can increase the numbers of responding T cells and can mediate significant anti-tumor activity. CDX-1127 was also shown to directly impact tumor cells expressing CD27. The solid tumor indications that can enroll into the Phase 1 study include; refractory patients with metastatic melanoma, renal (clear) cell carcinoma, hormone-refractory prostate adenocarcinoma, ovarian and colorectal adenocarcinoma, and non-small cell lung 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 (PTI) 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-011, CDX-1135 (formerly TP10), CDX-1401, CDX-1127, CDX-301, Belinostat 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, including the additional capital which will be necessary to complete the clinical trials that we plan to initiate in 2011; 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; the uncertainties inherent in clinical testing; our limited experience in bringing programs through Phase 3 clinical trials; our ability to manage research and development efforts for multiple products at varying stages of development; the timing, cost and uncertainty of obtaining regulatory approvals; the failure of the market for the Company's programs to continue to develop; our limited cash reserves and our ability to obtain additional capital on acceptable terms, or at all; our ability to protect the Company’s intellectual property; the loss of any executive officers or key personnel or consultants; competition; changes in the regulatory landscape or the imposition of regulations that affect the Company’s products; and other risks detailed from time to time in the Company's filings with the Securities and Exchange Commission, including the Company's Form 10-K for the fiscal year ended December 31, 2010, and its Forms 10-Q and 8-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.