Novel Targeted Radiation Therapy From Immunomedics Produces Objective Responses in Pancreatic Cancer

Immunomedics today reported a 30% objective response rate in 10 evaluable patients with inoperable, advanced pancreatic cancer treated with a novel targeted radiation therapy developed by the Company in combination with gemcitabine

ORLANDO, FL, USA | May 31, 2009 | Immunomedics, Inc. (Nasdaq:IMMU), a biopharmaceutical company focused on developing monoclonal antibodies to treat cancer and other serious diseases, today reported a 30% objective response rate in 10 evaluable patients with inoperable, advanced pancreatic cancer treated with a novel targeted radiation therapy developed by the Company in combination with gemcitabine. Interim results from the ongoing Phase Ib dose-escalation study were presented at the 2009 Annual Meeting of American Society of Clinical Oncology.

"Targeted radiation therapy is well suited for solid cancers, such as pancreatic cancer, and our data, though limited, corroborate this notion," remarked Cynthia L. Sullivan, President and CEO. "In light of the fact that there aren't many viable treatment options for patients with advanced pancreatic cancer, we believe clivatuzumab tetraxetan labeled with yttrium-90 is in a good position to become the first radioimmunotherapeutic agent for pancreatic cancer therapy, and we currently intend to develop it through commercialization on our own," continued Ms. Sullivan.

Eleven treatment-naive patients, of which all but 1 had stage 4 or metastatic pancreatic cancer, were enrolled in this dose exploration study to receive 1 of 3 fractionated yttrium-90 (Y-90) doses: 6.5, 9.0 and 12.0 mCi/m(2), given once a week for 3 weeks in combination with low doses of gemcitabine as a radiosensitizing agent. Two of 3 patients at the 12.0 mCi/m(2) dose level had more than 30% tumor shrinkage to qualify as partial responders by RECIST criteria. The third patient is too early for evaluation, but is showing evidence of tumor shrinkage. One patient receiving 6.5 mCi/m(2) of Y-90 also was a partial response. Overall, half of the evaluable patients showed evidence of tumor shrinkage or stabilization after this therapy.

In addition, 2 patients survived for more than 1 year from the start of treatment, despite the dismal life expectancy of 4 to 6 months from diagnosis for most patients with advanced pancreatic cancer, due to lack of early detection and effective treatment. One had received 4 cycles of this therapy, and the other received three.

The targeted radiation therapy penetrates and kills cancer cells by using the Company's patented humanized monoclonal antibody called clivatuzumab, or hPAM4, to deliver beta-radiation beams produced by the radioisotope, yttrium-90, directly to the tumor. Clivatuzumab binds to 85% of pancreatic cancers, but does not target cells in normal pancreas or pancreatitis.

In addition to getting Y-90 clivatuzumab tetraxetan, patients also received 4 weekly doses of 200 mg/m(2) of gemcitabine known to sensitize cancer cells to radiation, and which was given much below its usual therapeutic dose. The major side effect from the combination treatment is low blood cell counts which are manageable and reversible. Otherwise, the treatment has been well tolerated. The study is ongoing with the next group of patients expected to receive 15.0 mCi/m(2) of Y-90 weekly for 3 weeks.

Y-90 clivatuzumab tetraxetan has been designated by the U.S. Food and Drug Administration (FDA) as a fast-track product, and has orphan drug status in both the U.S. and the European Union for the therapy of pancreatic cancer.

About Y-90 Clivatuzumab Tetraxetan

Clivatuzumab 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 Y-90 PAM4 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 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 2009, an estimated 42,470 Americans will be diagnosed with the disease, and about 35,240 patients will die from it. For all stages combined, the 1- and 5-year survival rates are 24% and 5% respectively. Even for those people diagnosed with local disease, the 5-year survival is only 20%. 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 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 134 patents issued in the United States and more than 300 other patents issued worldwide, protects our product candidates and technologies. 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.

SOURCE: Immunomedics, Inc.

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