Celldex Therapeutics Makes Significant Advancements in the Field of Protein-Based Vaccine Development

  Celldex Therapeutics Makes Significant Advancements in the Field of
  Protein-Based Vaccine Development

   --Dendritic Cell Targeted Vaccine CDX-1401 is Well-tolerated and Elicits
        Robust Antibody and T cell Responses in Patients with Cancer--

Business Wire

NEEDHAM, Mass. -- October 29, 2012

Celldex Therapeutics, Inc. (NASDAQ: CLDX) today announced positive results
demonstrating promising clinical effects in a Phase 1 study of CDX-1401 in
solid tumors in combination with the toll-like receptor (TLR) agonists
resiquimod and/or Poly ICLC (Hiltonol^TM). CDX-1401 is a fusion protein
consisting of a fully human monoclonal antibody with specificity for the
dendritic cell receptor DEC-205 linked to the NY-ESO-1 tumor antigen. The
NY-ESO-1 antigen is expressed in a variety of cancer cells. Targeting protein
antigens to the DEC-205 receptor on dendritic cells was pioneered by the late
Ralph Steinman, MD, a member of Celldex’s Scientific Advisory Board. Dr.
Steinman received the 2011 Nobel Prize in Physiology or Medicine for his
discovery of the dendritic cell and its role in adaptive immunity. In
preclinical studies, CDX-1401 has been shown to induce potent and broad
immunity. The Phase 1 study of CDX-1401 is the first clinical study to
demonstrate that an off-the-shelf vaccine that targets dendritic cells in vivo
through DEC-205 can safely lead to robust humoral and cellular immunity when
combined with TLR agonists in cancer patients - overcoming a significant
challenge in the development of protein based vaccines.

“In the CDX-1401 study, we were able to translate the important preclinical
work led by Dr. Steinman’s lab into clinical benefit, generating protein
specific immunity including both antibody and T cell responses in patients
with advanced cancers known to express NY-ESO-1. This is an important
milestone for the field of targeted vaccine development and for the
development of CDX-1401 specifically. Importantly, some patients had evidence
of clinical benefit with significant stable disease and measurable tumor
shrinkage, despite their advanced stage of metastatic disease. The ability to
target proteins to dendritic cells represents a promising approach for the
next generation of vaccines against pathogens and cancer,” said Madhav V.
Dhodapkar, MBBS, Arthur H. and Isabel Bunker Professor of Medicine and
Immunobiology, Chief of the Section of Hematology at the Department of
Internal Medicine and Clinical Research Program Leader of the Hematology
Program at Yale Cancer Center and the lead investigator of the study.

“CDX-1401 is at the forefront of a new generation of off-the-shelf dendritic
cell targeted vaccines that Celldex believes hold significant promise as a
platform for protein-based vaccines,” said Tibor Keler, PhD, Chief Scientific
Officer of Celldex Therapeutics. “The immunological and clinical data
demonstrated in this study clearly support continued investigation and we plan
to study additional combination regimens of CDX-1401 in melanoma and other
indications where we believe a dendritic cell vaccine regimen could play an
important role. We expect that a study sponsored by the Cancer Immunotherapy
Trials Network will be initiated in 2013.”

The results from the Phase 1 study of CDX-1401 were presented in a poster
session entitled, “A Phase 1 Trial of a Novel Vaccine Targeting NY-ESO-1 to
the Dendritic Cell Receptor DEC-205 in Combination with Toll-like Receptor
Agonists” at the Society for Immunotherapy Annual Meeting on Friday, October
26, 2012 by Dr. Dhodapkar. The study was conducted at multiple centers
including Yale Cancer Center, Henry Ford Hospital and Medical Group, Memorial
Sloan Kettering Cancer Center, Weill Cornell Medical College, Providence
Portland Medical Center, Mount Sinai Medical Center and the Carolina
BioOncology Institute.

Study results:

The Phase 1 study of CDX-1401 assessed the safety, immunogenicity and clinical
activity of escalating doses of CDX-1401 plus resiquimod and/or Poly ICLC in
45 patients with advanced malignancies (21 melanoma, six ovarian, five
sarcoma, four non-small cell lung cancer, four colorectal, five other) that
had progressed after any available curative and/or salvage therapies. 87% of
patients had distant metastases at entry. 60% of patients had confirmed NY-ESO
expression in archived tumor sample. Ten patients received multiple cycles of
the treatment regimen (six weeks of treatment followed by a six week rest),
including five patients who received three or more cycles. Eight patients
completed two years on study and eight patients remain in follow-up. Thirteen
patients maintained stable disease for up to 13.4 months with a median of 6.7
months. In addition, two patients had significant tumor shrinkage (-20% and
-21% decrease in area of target lesions). Treatment was well-tolerated and
there were no dose limiting toxicities.

Significant anti-NY-ESO-1 titers (up to 1:800,000) occurred in 79% (33/42) of
evaluable patients. Approximately 54% of patients with NY-ESO-1 positive
tumors had anti-NY-ESO-1 titers at baseline and most increased after
vaccination. Humoral responses were elicited in both NY-ESO-1 positive and
negative patients. NY-ESO-1-specific T cell responses were absent or low at
baseline, but increased post-vaccination in 53% (18/34) of evaluable patients,
including both CD4 and/or CD8 T cell responses. Robust immune responses were
observed with CDX-1401 with resiquimod and Poly ICLC alone and in combination.
Importantly, a well-tolerated and immunogenic regimen has been identified to
take forward into the future study.

About the CDX-1401 Vaccine

CDX-1401 is a next-generation, off-the-shelf, cancer vaccine designed to
activate the patient's immune system against cancers that express the tumor
marker, NY-ESO-1. The product consists of a fully human monoclonal antibody
with specificity for the dendritic cell receptor DEC-205 genetically linked to
the NY-ESO-1 tumor antigen. Celldex has accessed NY-ESO-1 through a licensing
agreement with the Ludwig Institute for Cancer Research. By selectively
delivering the NY-ESO-1 antigen to dendritic cells in the body, this product
candidate is intended to induce robust immune responses against the
antigen-expressing cancer cells.

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 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, 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 limited cash reserves and 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 have initiated or plan to initiate; our ability to adapt APC Targeting
Technology^TM 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 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
factors listed under “Risk Factors” in our annual report on Form 10-K.

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We have no obligation, and expressly disclaim any obligation, to update,
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of new information, future events or otherwise.

Contact:

Celldex Therapeutics, Inc.
Sarah Cavanaugh, 781-433-3161
Vice President of IR & Corp Comm
scavanaugh@celldextherapeutics.com
or
For Media:
BMC Communications
Brad Miles, 646-513-3125
bmiles@bmccommunications.com