Immunomedics Presents Epratuzumab's Mechanism of Action in Systemic Lupus Erythematosus

Immunomedics Presents Epratuzumab's Mechanism of Action in Systemic Lupus

Oral Presentation at EULAR 2013 Congress

MADRID, Spain, June 13, 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 reported that epratuzumab, the
Company's humanized anti-CD22 antibody, mediates the reduction of select
proteins on the surface of B cells via a process known as trogocytosis, and
that such reduction could modulate B-cell activities.Results from this study
were presented by Edmund A. Rossi, Ph.D., Executive Director, Recombinant

Epratuzumab is currently in two UCB-conducted Phase III pivotal trials for the
treatment of patients with systemic lupus erythematosus (SLE). UCB holds the
worldwide development rights for epratuzumab in autoimmune diseases, while the
Company retains all rights in oncology. In earlier clinical studies in SLE and
in non-Hodgkin lymphoma (NHL), epratuzumab has been shown to deplete about
30-40% of circulating B cells in patients. However, the mechanism of action of
epratuzumab, especially its involvement in regulating B-cell antigen receptor
(BCR) signaling, has yet to be fully elucidated.

In this preclinical study, treatment of peripheral blood mononuclear cells
(PBMCs) with epratuzumab significantly reduced the levels of select B-cell
surface proteins, including CD22, CD19, CD21 and CD79b. Corroboratively, SLE
patients on epratuzumab therapy also showed significantly lower levels of
CD22, CD19 and CD21, compared to treatment-naïve patients. Although
internalization of CD22 upon epratuzumab binding is known and expected,
reduction of the other BCR proteins presents a new finding. The reduction of
CD19 is of particular interest since elevated levels of this protein on the
surface of B cells have been implicated in SLE.

Another key finding from this study is the formation of immunological synapses
between B cells and effector cells, such as monocytes, natural killer cells
and granulocytes, induced by epratuzumab. By binding to B cells and effector
cells simultaneously, epratuzumab serves as a conduit for the transfer of the
BCR-associated receptors, lowering their presence on B cells.

This process of trogocytosis occurred on B cells from healthy volunteers, NHL
or SLE patients, over a broad concentration range between 10 ng/mL – 100 mg/mL
of epratuzumab. This may explain the clinical observations that higher doses
(720 mg/m^2 weekly x 4) of epratuzumab were less effective than a mid-range
dose (360 mg/m^2 weekly x 4), because a serum concentration of epratuzumab
greater than 150 µg/mL may reduce trogocytosis efficiency.

"We believe epratuzumab-mediated trogocytosis could modulate B-cell proteins
involved in regulating BCR signaling and cell-cell communication, resulting in
altered B-cell functions that ultimately mitigate symptoms of SLE and other
autoimmune diseases, without major depletion of B cells," commented Cynthia L.
Sullivan, President and Chief Executive Officer. "This study could potentially
lead to the design of more effective therapy and the correct dosing for B-cell
mediated autoimmune diseases and cancer," concluded Ms. Sullivan.

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 223 active patents in the United States and more
than 400 foreign patents, protects our product candidates and
technologies.Our strength in intellectual property has resulted in the top-10
ranking in the 2012 IEEE Spectrum Patent Power Scorecards in the Biotechnology
and Pharmaceuticals category.For additional information on us, please visit
our website at 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
Press spacebar to pause and continue. Press esc to stop.