Immunomedics Reports Progress With Labeling Proteins, Including Antibodies, for Improved PET Imaging

Immunomedics Reports Progress With Labeling Proteins, Including Antibodies,
for Improved PET Imaging

Oral Presentation on Patented F-18 Labeling Method at SNMMI 2013 Annual
Meeting

VANCOUVER, British Columbia, June 12, 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 progress with
labeling temperature-sensitive molecules using fluorine-18 (^18F) for improved
positron-emission tomography (PET) imaging of diseases. Results of this study
were presented by William McBride, Ph.D., Senior Director, Peptide Chemistry.

The Company previously published a novel method of radiolabeling peptides with
^18F known as AlF.^1 Eleven publications have since tracked the development of
this patented method, including a recently published review.^2 The Company
simplified the approach with the development of a lyophilized kit that permits
the radiolabeling of peptides within about 20 minutes, with yields exceeding
70% and high specific activity.^3 A similar radiolabeling kit utilizing the
AlF technology was recently validated clinically by National Institute of
Health scientists, in collaboration with Chinese physicians, who successfully
imaged all sites of tumor in 9 lung cancer patients with a ^18F-labeled
peptide.^4 More importantly, as recently reported by us
(http://www.immunomedics.com/pdfs/news/2013/pr05282013.pdf), this method is
now protected by 11 U.S. issued patents.

^18F labeling by the AlF procedure requires the use of metal-binding ligands,
such as NODA or NOTA, which capture a highly stable aluminum-^18F complex. The
Company previously reported the creation of the NODA-MPAA ligand for highly
efficient direct radiolabeling of peptides and other compounds that can
withstand high temperatures, and introduced a 2-step procedure that could be
used for radiolabeling heat-sensitive compounds, such as antibody fragments.
(For more information, please visit the Company's press release at
http://www.immunomedics.com/pdfs/news/2011/pr06082011.pdf).

The current study presented at this year's SNMMI Annual Meeting was aimed at
creating new NODA-based ligands for improved radiofluorination yields at lower
temperatures. Two new ligands, a pyridine-NODA and a triazole-NODA, were
synthesized and shown to have higher labeling yields than NODA-MPAA,
especially at lower temperatures. Furthermore, no co-solvent was needed for
the peptide linked with triazole-NODA ligand. Both of the F-18-labeled
peptides were stable in human serum at 37^oC for at least 4 hours.

In a second oral presentation at this year's SNMMI Annual Meeting, Shankar
Vallabhajosula, Ph.D., Nuclear Medicine/Molecular Imaging, Weill Cornell
Medical College, New York, NY, reported progress toward the commercial
development of radiopharmacy manufacturing to prepare multi-dose ^18F labeled
peptides and proteins using the Company's patented AlF-labeling method. Their
new study evaluated processes aimed at optimizing the radiolabeling procedure
for multi-dose preparation of IMP485, a hapten-peptide used for pretargeting,
a highly sensitive and specific method for targeting cancers using a
bispecific antibody.^5

The optimized procedure had 60% yields, with specific activity high at 5.1 Ci
(137.8 GBq)/μmole. Sep-Pak purification resulted in >90% radiochemical purity
(RCP) and HPLC purification was not required. The investigators further found
that a widely used and simple procedure known as instant thin-layer
chromatography (ITLC) using silicon gel and water was suitable for the
assessment of RCP. Using these procedures, ^18F-IMP-485 may be an ideal
radiopharmaceutical for ImmunoPET studies based on the pretargeting approach
pioneered by the Company.

This study was supported in part by Award Number R44RR028018 from the National
Center for Research Resources and the National Institute of Biomedical Imaging
and Bioengineering of the National Institutes of Health.

Reference

1.McBride W.J., Sharkey R.M., Karacay H., D'Souza C.A., Rossi E.A., Laverman
    P., Chang C.H., Boerman O.C., Goldenberg D.M. A novel method of 18F
    radiolabeling for PET. J Nucl Med. 2009 Jun;50(6):991-8. doi:
    10.2967/jnumed.108.060418. Epub 2009 May 14.
    
2.McBride W.J.,Sharkey R.M.,Goldenberg, D.M. Radiofluorination using
    aluminum-fluoride (Al18F). EJNMMI Research 2013 May
    8;3(1):36.doi:10.1186/2191-219X-3-36.
    
3.McBride W.J., D'Souza C.A., Karacay H., Sharkey R.M., Goldenberg D.M. New
    lyophilized kit for rapid radiofluorination of peptides. Bioconjug Chem.
    2012 Mar 21;23(3):538-47. doi: 10.1021/bc200608e. Epub 2012 Feb 10.
    
4.Wan W., Guo N., Pan D., Yu C., Weng Y., Luo S., Ding H., Xu Y., Wang L.,
    Lang L., Xie Q., Yang M., Chen X. First experience of 18F-alfatide in lung
    cancer patients using a new lyophilized kit for rapid radiofluorination. J
    Nucl Med. 2013 May;54(5):691-698. doi: 10.2967/jnumed.112.113563. Epub
    2013 April 3.
    
5.Goldenberg D.M., Chang C.H., Rossi E.A., McBride W.J., Sharkey R.M.
    Pretargeted molecular imaging and radioimmunotherapy. Theranostics. 2012;
    2(5):523-40. doi: 10.7150/thno.3582. Epub 2012 May 17.

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 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