Immunomedics Reports Final Results From Phase Ib/II Study of Yttrium-90-Labeled Clivatuzumab Tetraxetan and Gemcitabine in Advanced Pancreatic Cancer

Multicenter Two-Part Study Presented at 2012 Gastrointestinal Cancers Symposium

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| Source: Immunomedics, Inc.

SAN FRANCISCO, Jan. 20, 2012 (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 repeated cycles of fractionated doses of its proprietary humanized antibody, clivatuzumab tetraxetan, labeled with yttrium-90 (90Y) and given in combination with gemcitabine, demonstrated therapeutic activity in patients with advanced, inoperable, pancreatic cancer.

A total of 100 patients with previously untreated Stage III or IV pancreatic cancer were enrolled into this open-label trial to receive gemcitabine once-weekly x 4 with 90Y-clivatuzumab tetraxetan on weeks 2, 3 and 4 (therapy cycle). The therapy cycle could be repeated until disease progression or patient displayed unacceptable toxicity. Ten patients withdrew early, while 90 patients, of whom 82 had the Stage IV (metastatic) disease, received 1 – 4 therapy cycles.

In Part I of this study, 38 patients were treated with 90Y-clivatuzumab tetraxetan at 6.5, 9, 12 or 15 mCi/m2 x 3, and a low, fixed gemcitabine dose of 200 mg/m2 x 4 for radiosensitization. Thirteen patients were retreated with the same cycle 1 - 3 times. The overall disease control rate, which includes complete response (CR), partial response (PR) and stable disease (SD), by CT-based RECIST criteria, was 58%, including 6 patients (16%) with PR and 16 patients (42%) with SD as best response.

The median overall survival (OS) for the 38 treated patients was 7.7 months, which compares favorably with other regimens for advanced pancreatic cancer. At the higher therapy doses (12 and 15 mCi/m2 of 90Y-clivatuzumab tetraxetan x 3), a median OS of 8.0 months was noted. For the 13 patients who received repeated cycles of the combination therapy, median OS improved to 11.8 months. (For more information, please refer to the Company's press release at www.immunomedics.com/pdfs/news/2011/PR06072011.pdf). 

Fifty-two patients were treated in Part II of this study to receive 3 weekly 90Y doses of 12 mCi/m2 and gemcitabine doses of 200, 600 or 1000 mg/m2 x 4, with 14 patients receiving repeated therapy cycles at the same gemcitabine dose but 90Y doses of 6.5, 9 or 12 mCi/m2. Results from 47 patients were reported at the Symposium. The disease control rate for the 200 mg/m2 group was 72%, with 19% PR and 53% SD. For the 600 and 1000 mg/m2 groups, the disease control rates were 63% (0% PR) and 68% (18% PR), respectively. Higher gemcitabine doses appeared to offer no advantage in treatment response over the lowest dose of 200 mg/m2. At the time of reporting, survival data were not available for this group of patients.

"These results from Part II of this clinical trial continue to support the use of antibody-directed radiation therapy with 90Y-clivatuzumab tetraxetan in patients with late-stage pancreatic cancer," remarked Cynthia L. Sullivan, President and Chief Executive Officer. "We are in discussions with FDA and opinion leaders regarding further development and eventual registration of this novel therapy modality," Ms. Sullivan added.

Treatments were well tolerated with no infusion reactions to radiolabeled clivatuzumab and few non-hematologic side effects. Hematologic suppression was transient after cycles 1 and 2.

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 90Y-clivatuzumab tetraxetan in treatment-relapsed pancreatic cancer patients has also produced encouraging results, with evidence of objective responses. The radiolabeled humanized antibody recently completed 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 for both sexes in the United States. The death rate for pancreatic cancer increased by 0.4% per year from 2004 to 2008, despite a reduction in overall cancer death rates since 1990. In 2012, an estimated 37,390 Americans are expected to die from the disease. With about 43,920 new cases in 2012, incidence rates of pancreatic cancer are also on the rise, increasing by 1.5% per year since 2004. For patients with advanced cancers, the median survival is 5.65 months. The overall 1-and 5-year relative survival rates for all stages are 26% and 6%, respectively. 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 189 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 http://www.immunomedics.com/">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 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.

Dr. Chau Cheng
Director, Investor Relations & Grant Management
(973) 605-8200, extension 123