Positive Data From Celldex's Phase 1 Study of CDX-301 Support Initiation of Pilot Study in Hematopoietic Stem Cell

Positive Data From Celldex's Phase 1 Study of CDX-301 Support Initiation of
Pilot Study in Hematopoietic Stem Cell Transplantation

Final Study Results Presented in an Oral Session at the 2013 BMT Tandem

NEEDHAM, Mass., Feb. 14, 2013 (GLOBE NEWSWIRE) -- Celldex Therapeutics, Inc.
(Nasdaq:CLDX) presented final results yesterday from a Phase 1 study of
CDX-301 (recombinant human Flt3L; rhuFlt3L) in healthy volunteers that
strongly support the initiation of a pilot study in hematopoietic stem cell
transplantation later this year. The data were presented by Michael Yellin,
MD, Vice President of Clinical Science at Celldex, in an oral presentation at
the American Society for Blood and Marrow Transplantation 2013 BMT Tandem
Meetings. The study was conducted at Rockefeller University by Niroshana
Anandasabapathy, MD, PhD, who worked as an instructor in clinical
investigation in the laboratory of the late Nobel Laureate Ralph Steinman, MD.

"The final results from this study are consistent with previous clinical
experience and demonstrate that CDX-301 is well-tolerated and can effectively
mobilize hematopoietic stem cell populations as a single agent in healthy
volunteers," said Dr. Yellin. "Based on the safety profile and the impressive
increases observed for CD34+ stem cells and dendritic cells, we believe
CDX-301 holds significant promise in both the allogeneic and autologous
transplant setting, including the potential for combination with other
molecules that could work in synergy with CDX-301 to further enhance the
mobilization of hematopoietic stem cell populations. Published pre-clinical
Flt3L studies also suggest that CDX-301 could potentially improve engraftment
and reduce the risk of graph versus host disease. This may be especially
important for older patients and patients who are in poor health."

Study results:

30 healthy volunteers were enrolled across seven cohorts. The first five
cohorts assessed escalating doses of CDX-301 (from 1 mcg/kg to 75 mcg/kg) as a
five-day regimen, while the final two cohorts assessed CDX-301 (at 25 mcg/kg)
as seven- and 10-day regimens. All volunteers completed dosing and safety
follow-up. Short-term dosing of five days resulted in a median of 10-fold
increases in CD34+ cells—stem cells that have the ability to give rise to all
cell types in the blood. Of note, on day 10 of dosing, a greater than 100-fold
increase in dendritic cells—cells believed to play a critical role in the
long-term improvement of transplant outcome—was observed in the peripheral
blood. CDX-301 was generally well-tolerated with transient grade 1
lymphadenopathy observed in six volunteers (all treated at the highest dose
levels of 25 mcg/kg and 75 mcg/kg). No anti-CDX-301 antibodies were detected
in any volunteers through the end of study follow-up.

CDX-301 or rhuFlt3L is a potent cytokine that stimulates the expansion and
differentiation of hematopoietic progenitor and stem cells. rhuFlt3L has
demonstrated a unique capacity to increase the number of circulating dendritic
cells in both laboratory and clinical studies. In addition, rhuFlt3L has shown
impressive results in models of cancer, infectious diseases and
inflammatory/autoimmune diseases. The clinical safety and activity of rhuFlt3L
were originally demonstrated by Immunex (now Amgen) in clinical trials
involving more than 150 healthy volunteers and 380 patients with cancer.
Recognizing the promise of CDX-301, Celldex in-licensed the program from Amgen
in 2009. Celldex's completion of this recent Phase 1 study confirms and builds
upon the extensive prior clinical experience and reaffirms the significant
potential for CDX-301.

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.

Safe Harbor Statement Under the Private Securities Litigation Reform Act of

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.

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.

CONTACT: Sarah Cavanaugh
         Vice President of IR & Corp Communications
         Celldex Therapeutics, Inc.
         (781) 433-3161
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