Pancreatic Cancer-Specific Radiolabeled Antibody Combined With Low-Dose Gemcitabine Chemotherapy Continues to Provide Evidence of Activity in Phase Ib/II Clinical Trial

CHICAGO, IL, USA | June 7, 2010 | Immunomedics, Inc. (Nasdaq:IMMU – News), a biopharmaceutical company focused on developing monoclonal antibodies to treat cancer and other serious diseases, today announced that its proprietary antibody, clivatuzumab tetraxetan, labeled with yttrium-90 (Y-90) plus low-dose gemcitabine continues to produce promising efficacy results in patients with previously untreated, inoperable, locally advanced or metastatic pancreatic cancer.

At the 2010 American Society of Clinical Oncology annual meeting, Dr. Allyson Ocean of the New York Presbyterian Hospital, Weill Medical College of Cornell University, New York, NY, reported for the research team that among the 37 evaluable patients, the disease control rate for all dose groups combined was 57%, including 6 patients (16%) with partial responses (PR) by RECIST criteria (i.e., responses showing decreases in tumor size of more than 30% by CT and in the absence of new lesions) and 16 patients (41%) with stable disease (SD). Most promising efficacy was observed in the group of 16 patients that received 12 mCi/m2 of Y-90 weekly for 3 weeks, with a 69% disease control rate (19% PR and 50% SD). In addition, anecdotal reports indicated patients have good performance and decreased pain medication after treatment.

"These updated results continue to show evidence of tumor shrinkage and stabilization in about 60% of evaluable patients, but most importantly without the usual toxicities accompanying aggressive chemotherapy regimens," commented Dr. Ocean.

At the time of reporting, 15 patients (41%) have achieved survival longer than 6 months. This includes 4 patients (11%) at lower doses who received 1-3 additional cycles with survival for more than 1 year. Progression-free survival and overall survival data need more follow-up, particularly for more recent patients entered at higher Y-90 dose levels.

"We are pleased that this ongoing Phase Ib/II study is experiencing rapid patient enrollment and that results continue to be encouraging in this dismal disease," remarked Cynthia L. Sullivan, President and CEO of Immunomedics.

Of the 37 evaluable patients, 25 received one cycle, while 13 patients were retreated, with 11 receiving 2 cycles and 1 patient each receiving 3 or 4 cycles.

The study also showed that responses increased with higher doses of Y-90 since there were 19% PR in patients given 12 mCi/m2 weekly for 3 weeks compared with 8% at the 9 mCi/m2 dose level. In spite of higher cumulative Y-90 doses, treatment was well tolerated with few non-hematologic side effects. Hematologic suppression was manageable without major infections or bleeding events, and reversible in most patients, even after 4 treatment cycles.

The clinical research team conducting this study included physicians and staff from New York (New York Presbyterian Hospital, Weill Medical College of Cornell University), Delaware (Helen F. Graham Cancer Center at Christiana Care, Newark), Indiana (Goshen Center for Cancer Care), North Carolina (University of North Carolina at Chapel Hill), Florida (University of Miami Sylvester Comprehensive Cancer Center; Florida International University Herbert Wertheim College of Medicine, Miami), Ohio (Ohio State University College of Medicine, Columbus) and New Jersey (Garden State Cancer Center, Belleville; Immunomedics, Inc., Morris Plains).

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 149 patents issued in the United States and more than 375 other patents issued worldwide, protects our product candidates and technologies. For additional information on us, please visit our website at www.immunomedics.com.

SOURCE: Immunomedics, Inc.