Immunomedics Creates Novel Antibody-Cytokine Conjugates for Cancer Therapy

Immunomedics Creates Novel Antibody-Cytokine Conjugates for Cancer Therapy

    -- Preclinical Study Presented at 2013 Annual Meeting of the American
                  Association for Cancer Research (AACR) --

         -- Study on Mechanism of Cancer Metastasis also Reported--

WASHINGTON, April 8, 2013 (GLOBE NEWSWIRE) --Immunomedics, Inc.
(Nasdaq:IMMU), a biopharmaceutical company primarily focused on the
development of monoclonal antibody-based products for the targeted treatment
of cancer, autoimmune and other serious diseases, today announced the creation
of a new class of antibody-cytokine conjugates using the Company's patented
DOCK-AND-LOCK™ (DNL™) platform technology. These DNL™ complexes demonstrated
potent anti-tumor activity in preclinical studies.

The Company has previously reported the development of antibody-directed
interferon-alpha 2b (IFN alpha 2b) complexes. (For more information, please
refer to the Company's press release at
www.immunomedics.com/pdfs/news/2009/PR04222009A.pdf). Veltuzumab-IFN alpha 2b
is the most advanced product from this group of IFN alpha-based DNL™
complexes, and is currently being developed for improved therapy of B-cell
malignancies, partially supported by a grant from the Small Business
Innovation Research program of the National Cancer Institute totaling $2.8
million.

While functioning similarly to IFN-alpha in eliciting anti-viral, anti-tumor,
and immune-modulating activities, IFN-lambda is being considered as a
potential alternative to existing IFN-alpha therapeutic regimens due to its
more restricted cellular targets. Antibody-targeted IFN- lambda may further
improve its safety, potency and pharmacokinetics.

In the current study, 3 DNL^TM complexes of IFN- lambda, designated (E1)-
lambda 1, (15)- lambda 1, and (C2)- lambda 1, were generated by
site-specifically conjugating IFN- lambda 1 to 3 of the Company's proprietary
humanized antibodies, hRS7 (anti-TROP-2), hMN-15 (anti-CEACAM6), and hL243
(anti-HLA-DR), respectively. These antibody-cytokine conjugates were evaluated
in human malignant cell lines of cervix, colon, esophagus, lung, liver, and
skin.

Targeting of these antibody-cytokine conjugates to antigen-expressing cells
markedly increased the amount of IFN- lambda 1 localized at the cell surface.
As a result, (E1)- lambda 1 inhibited the in vitro proliferation of the
cervical, lung and esophageal cancer cell lines at less than 1 picomolar (pM)
concentration, which was 1,000-fold more potent than commercial IFN- lambda 1.
Likewise, the anti-proliferation activity of (15)- lambda 1 was enhanced
~100-fold in cervical and esophageal cancer cells, but not in CEACAM6-negative
lung cancer cells.

"These promising results, attributable to increased localization and stronger
binding to antibody-targeted cells, warrant further exploration as potential
cancer therapeutics," remarked Cynthia L. Sullivan, President and Chief
Executive Officer.

Cancers are generally believed to be derived from single cells that are
genetically mutated, resulting in many divisions resulting in an expanding
tumor that eventually spreads to local and distant organs. Cancer deaths
usually are due to this metastasis affecting the new organs invaded. The
initiating cells are often referred to as cancer stem cells. How these turn
into heterogeneous populations of cancer cells within the original tumor and
even in the metastases is the subject of intense recent research, which has
also focused on the tumor's microenvironment and how cancer cells interact
with their neighboring supportive cells.

In a separate poster presentation at the same AACR Annual Meeting, the Company
reported that genes of human cancer jump into adjacent normal cells by fusion
of both cells. This study was done in collaboration with researchers from the
Garden State Cancer Center, Center for Molecular Medicine and Immunology in
Morris Plains, NJ, and the Laboratory of Pathology, Center for Cancer
Research, National Cancer Institute, NIH, in Bethesda, MD.

This team of scientists discovered a transfer of human genes to normal hamster
cells when cells from tissues involved by Hodgkin's lymphoma from two patients
were implanted to hamsters. In all, 7 of 24 human genes tested were present in
the malignant tumors growing in the hamsters for extended periods of 5 to 6
years, with evidence of metastasis in the hamsters within 21 days of the
original grafting of the human tumors. By means of sensitive DNA coloring of
the tumor cells, the investigators proved that human and hamster DNA were
present in single cancer cells, representing fused cells of both species.

"These findings may explain how cancers develop and change with time,
spreading by metastasis to other organs by overcoming immunity to the cancer
cells and could lead to therapeutic strategies," commented the lead
investigator, Dr. David M. Goldenberg, Chief Scientific Officer and Chief
Medical Officer of Immunomedics, and President of the Center for Molecular
Medicine and Immunology.

About Immunomedics

Immunomedics is a New Jersey-based biopharmaceutical company primarily focused
on the development of monoclonal antibody-based products for the targeted
treatment of cancer, autoimmune and other serious diseases.We have developed
a number of advanced proprietary technologies that allow us to create
humanized antibodies that can be used either alone in unlabeled or "naked"
form, or conjugated with radioactive isotopes, chemotherapeutics, cytokines or
toxins, in each case to create highly targeted agents.Using these
technologies, we have built a pipeline of therapeutic product candidates that
utilize several different mechanisms of action.We also have a majority
ownership in IBC Pharmaceuticals, Inc., which is developing a novel
DOCK-AND-LOCK™ (DNL™) method with us for making fusion proteins and
multifunctional antibodies, and a new method of delivering imaging and
therapeutic agents selectively to disease, especially different solid cancers
(colorectal, lung, pancreas, etc.), by proprietary, antibody-based,
pretargeting methods. We believe that our portfolio of intellectual property,
which includes approximately 220 active patents in the United States and more
than 400 foreign patents, protects our product candidates and technologies.
For additional information on us, please visit our website at
www.immunomedics.com. The information on our website does not, however, form a
part of this press release.

This release, in addition to historical information, may contain
forward-looking statements made pursuant to the Private Securities Litigation
Reform Act of 1995. Such statements, including statements regarding clinical
trials, out-licensing arrangements (including the timing and amount of
contingent payments), forecasts of future operating results, potential
collaborations, and capital raising activities, involve significant risks and
uncertainties and actual results could differ materially from those expressed
or implied herein. Factors that could cause such differences include, but are
not limited to, risks associated with any cash payment that the Company might
receive in connection with a sublicense involving a third party and UCB, which
is not within the Company's control, new product development (including
clinical trials outcome and regulatory requirements/actions), our dependence
on our licensing partners for the further development of epratuzumab and
veltuzumab for non-cancer indications, competitive risks to marketed products
and availability of required financing and other sources of funds on
acceptable terms, if at all, as well as the risks discussed in the Company's
filings with the Securities and Exchange Commission.The Company is not under
any obligation, and the Company expressly disclaims any obligation, to update
or alter any forward-looking statements, whether as a result of new
information, future events or otherwise.

CONTACT: For More Information:
         Dr. Chau Cheng
         Senior Director, Investor Relations & Grant Management
         (973) 605-8200, extension 123
         ccheng@immunomedics.com
 
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