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IMMU - Immunomedics Reports New Blood Test for Detecting Early Stage Pancreatic Cancer Correlates With Response to Clivatuzumab Tetraxetan Treatment

Press Release Source: Immunomedics, Inc. On Tuesday April 20, 2010, 2:00 pm

•Sensitivity for Detection of a Partial Response (PR) was 100% with a 68% Specificity
•Preclinical Results of Combining Clivatuzumab Tetraxetan and Antibody-Drug Conjugate also Reported


WASHINGTON, April 20, 2010 (GLOBE NEWSWIRE) -- Immunomedics, Inc. (Nasdaq:IMMU - News), a biopharmaceutical company focused on developing monoclonal antibodies to treat cancer and other serious diseases, today reported that a new blood test using the Company's proprietary humanized antibody, clivatuzumab or PAM4, predicted a partial response in an initial set of patients treated with a combination of the antibody labeled with yttrium-90 (Y-90) and gemcitabine. Results were presented at the 101st Annual Meeting of the American Association for Cancer Research.



"We have now demonstrated that the blood assay for PAM4-protein can not only detect early-stage pancreatic cancer, as has recently been reported by us, but may also predict a lack of response to therapy or an early relapse," remarked Cynthia L. Sullivan, President and CEO. "As a result, we believe we may be one step closer to offering an individualized approach for the management of this lethal disease," Ms. Sullivan added.



The challenge in pancreatic cancer is early diagnosis, before the disease has spread and treatment options become limited. To that end, the Company has recently developed a new serum-based enzyme immunoassay (ELISA) employing clivatuzumab that has a sensitivity of 62% for detecting stage-1 pancreatic cancer (disease confined to pancreas), 86% for stage 2 disease, and 91% for stage 3/4 (local and distant spread) cancers. (Please refer to the Company's press release at www.immunomedics.com/news_pdf/2010_PDF/PR01212010.pdf for details of these results). Using the same ELISA test, the current study examined changes in PAM4-protein level in the serum of patients treated with Y90-clivatuzumab, as a means to predict a partial response.



At the recent 2010 ASCO-GI Symposium, the Company reported an overall response rate of 68% with 5 patients having a partial response (PR), 10 with stable disease (SD) and 7 with progressive disease (POD). (For more information on the Phase I/II studies of clivatuzumab as a treatment for patients with pancreatic cancer, please refer to the Company's press release at www.immunomedics.com/news_pdf/2010_PDF/PR01252010.pdf). From this initial group of 22 patients, 17 were evaluable as having both baseline and follow-up sera available for PAM4 testing, of which 4 were PR, 11 patients with SD and 2 patients with POD. Notably, 1 patient was negative for PAM4 in the circulation and excluded from the evaluation.



The PAM4 ELISA correctly predicted 4 of 4 PRs. Four of 9 patients with SD were also predicted to have had a PR rather than an SD. However, it is noted that one of these SD patients had a 29% decrease in tumor size which is just under the 30% criteria under RECIST to qualify as a PR. Overall, the sensitivity for detection of a PR was 100% with a specificity of 68%. Importantly, neither of the patients with POD was falsely recognized as PR.



"Although these results are based on a small number of patients, the trend encourages us to expand such studies to evaluate whether this new bioassay for pancreatic cancer continues to be predictive of response to diverse therapies," Ms. Sullivan commented further.



Separately, in a study to be reported later in this conference, the effects of adding an antibody-drug conjugate that targets pancreatic cancer (hRS7-SN-38) to Y-90 labeled Clivatuzumab tetraxetan were investigated in a mouse model of human pancreatic cancer. Results showed that the combination produced more robust objective response than each agent alone. In particular, all animals receiving Y90-clivatuzumab at the maximum tolerated dose and hRS7-SN-38 achieved a tumor-free state within 4 weeks, while other animals continued to have evidence of persistent disease. These studies provide the first evidence that combined radioimmunotherapy and antibody-drug conjugate can enhance efficacy at safe doses.



About Clivatuzumab



Clivatuzumab or hPAM4 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 I/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 2009, an estimated 42,470 Americans were diagnosed with the disease, and about 35,240 patients died from it. It is often called a silent disease because it is difficult to detect and symptoms do not usually appear until the cancer has grown and often spread beyond the pancreas for quite some time. Pancreatic cancer is difficult to diagnose because there are no symptoms in the early stages and because, when symptoms appear, they can be confused with other diseases.



The treatment options depend on stage and location of the cancer, age, and general health of the patient. Potentially curative surgeries are performed when the cancer has started in the head of the pancreas (near the bile duct), which can allow earlier detection when bile duct blockage produces jaundice. Palliative surgery is a type of surgery chosen when the tumor is too widespread and is done to relieve the symptoms or complications caused by the cancer. If the cancer has not spread beyond the pancreas, therapy can be successful, but it is rare to find pancreatic cancer in the early stages. In later stages, various forms of chemotherapy or combinations of radiation and chemotherapy are given to try to control the disease, and ultimately therapy strives to comfort the patient and reduce pain.



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 148 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 http://www.immunomedics.com/. The information on our website does not, however, form a part of this press release.