updated 5/2/2011 10:46:33 AM ET 2011-05-02T14:46:33

MORRIS PLAINS, N.J., May 2, 2011 (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 that a single dose of clivatuzumab tetraxetan labeled with the potent therapeutic radioisotope, yttrium-90 (90Y), produced transient partial responses in some patients with advanced pancreatic cancer and the treatment was well tolerated with manageable hematological toxicity at the maximum tolerated 90Y dose.

Results from this Phase I study were published online in Clinical Cancer Research by S.A. Gulec, S.J. Cohen, K.L. Pennington, L.S. Zuckier, R.J. Hauke, H. Horne, W.A. Wegener, N. Teoh, D.V. Gold, R.M. Sharkey and D.M. Goldenberg in an article entitled "Treatment of advanced pancreatic carcinoma with 90Y-clivatuzumab tetraxetan: A Phase I single-dose escalation trial."

Pancreatic cancer continues to be one of the most difficult cancers to treat.   In this study, the initial clinical testing of a new antibody-targeted radiotherapeutic, 90Y-labeled-clivatuzumab tetraxetan, was performed.  This agent is the humanized version of the murine antibody, PAM4, which targets a mucin produced specifically by pancreatic carcinoma. In prior studies, PAM4 was effective as a single agent in arresting the growth, and even curing, human pancreatic carcinoma xenografts in animal models.  Additionally, preclinical studies indicated that when combined with gemcitabine, PAM4's therapeutic efficacy was improved.

While the ultimate goal is to evaluate 90Y-clivatuzumab tetraxetan in combination with gemcitabine as a treatment for patients with pancreatic cancer, it was necessary to first determine the maximum tolerated dose of 90Y-clivatuzumab tetraxetan given once as a single agent.

Twenty-one patients with advanced (Stages III and IV), mostly pretreated and relapsed, pancreatic adenocarcinoma were enrolled into this open-label, multicenter, dose-escalation study. Prior to therapy, all patients received a diagnostic dose of clivatuzumab tetraxetan labeled with the radioisotope, Indium-111 (111In), to ensure an acceptable distribution within the body and radiation dose to the pancreas for intended therapy. Patients then received a single infusion of 90Y-clivatuzumab tetraxetan with the 90Y dose escalating in increments of 5 mCi/m2, starting at 15 mCi/m2.  One patient withdrew before therapy.

Tumor targeting was observed in a majority of patients using the 111In-labeled antibody, and even though the mucin antigen is present in the serum, it did not appear to hinder the biodistribution or clearance of the antibody.  More importantly, 3 of 20 90Y-treated patients had CT-confirmed transient partial responses with 32-52% tumor diameter shrinkage, suggesting that additional studies with 90Y-clivatuzumab tetraxetan combined with gemcitabine should be pursued. All patients, however, showed disease progression at or after week 8. The maximum tolerated dose was 20 mCi/m2 with bone marrow being the dose-limiting organ. 

The radiolabeled humanized antibody is currently in a Phase Ib/II study using fractionated doses of 90Y in combination with gemcitabine as a therapy for patients with untreated advanced pancreatic cancer. Results from this study will be updated in an oral presentation at the Society of Nuclear Medicine annual meeting in June 2011. Moreover, results from the initial cohort of 42 patients treated with low-dose gemcitabine are being summarized for publication.

Commenting on these results, Cynthia L. Sullivan, President and Chief Executive Officer, stated, "We are currently in preparation for 2 Phase-III registration trials for this promising agent. After conferring with FDA and gaining guidance on the design of these trials, we have scheduled a meeting with opinion leaders and potential investigators during the annual meeting of the American Society of Clinical Oncology in June to present the current trial results and to seek their input and recommendations on our registration trial plans."

Results from this study were presented in part at the Gastrointestinal Cancer conference of the American Society of Clinical Oncology in January 2011.

About Clivatuzumab Tetraxetan

Clivatuzumab tetraxetan is a humanized monoclonal antibody targeting a mucin antigen expressed in most pancreatic cancers, but not pancreatitis, normal pancreas or most other normal tissues.  Preclinical studies in mice with human pancreatic cancer xenografts given the murine version of 90Y-clivatuzumab tetraxetan demonstrated favorable tumor responses, which could be further improved when given in combination with gemcitabine.  A prior Phase I single dose-escalation study of Y-90 clivatuzumab tetraxetan in treatment-relapsed pancreatic cancer patients has also produced encouraging results, with evidence of objective responses.  The radiolabeled humanized antibody is currently in a Phase Ib/II fractionated dose-escalation study in combination with gemcitabine for the treatment of patients with newly diagnosed, untreated, Stage III or Stage IV cancer of the pancreas.

About Pancreatic Cancer

According to the American Cancer Society, pancreatic cancer is the fourth leading cause of cancer death in the United States.  In 2010, an estimated 36,800 Americans died from the disease. It is also the eighth most frequently diagnosed cancer with about 43,140 new cases in 2010. For patients with advanced cancers, the median survival is 5.65 months. The overall 1-year survival rate for all stages is 25%. Currently, the standard therapy for pancreatic cancer is gemcitabine, alone or in combination with other chemotherapeutics.

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) methodology 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 175 patents issued 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, 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 new product development (including clinical trials outcome and regulatory requirements/actions), our dependence on our licensing partners for the further development of epratuzumab for autoimmune indications 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:  Dr. Chau Cheng
          Director, Investor Relations & Grant Management
          (973) 605-8200, extension 123
          ccheng@immunomedics.com

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