Immunomedics Reports Updated Results of Milatuzumab in Dose-Escalation Study for Multiple Myeloma

First Clinical Study of Anti-CD74 Antibody
Results Presented At 2009 Annual Meeting of ASCO

ORLANDO, FL, USA | May 30, 2009 | Immunomedics, Inc. (Nasdaq:IMMU - News), a biopharmaceutical company focused on developing monoclonal antibodies to treat cancer and other serious diseases, today announced that milatuzumab, the Company's proprietary humanized anti-CD74 antibody, produced disease stabilization in some patients with multiple myeloma and is well tolerated at doses up to 16.0 mg/kg.

CD74 is a transmembrane protein that is highly expressed in multiple myeloma and other B-cell lymphomas. Recent scientific research has found that CD74 is involved in a cell signaling pathway for proliferation and survival, and that binding of milatuzumab to CD74 blocks the pathway and leads to cell death. Milatuzumab has shown efficacy in preclinical B-lymphoma models, particularly multiple myeloma. In addition, milatuzumab is rapidly internalized when bound to its receptor, thus making CD-74 a promising target for conjugated drug delivery.

The goal of this first clinical study of milatuzumab is to evaluate its safety, tolerability, and feasibility in patients with multiple myeloma. Other objectives include preliminary information on efficacy, pharmacokinetics, immunogenicity; and acceptable doses for subsequent studies.

Adult patients with multiple myeloma were enrolled in this multicenter, open-label, dose-escalation study. All patients had stage II or III multiple myeloma, with stage III as the most advanced stage of the disease based on the Durie-Salmon diagnostic criteria. Most patients had at least 4 prior treatments that included bortezomib, lenalidomide, melphalan and thalidomide.

At the time of reporting, 24 patients have received milatuzumab, twice weekly, at 1 of 4 dose levels: 1.5, 4.0, 8.0 or 16.0 mg/kg, for 4 weeks. Milatuzumab was rapidly cleared at these dose levels with little accumulation in the blood. In spite of rapid clearance, 4 patients had encouraging disease stabilization for at least 12 weeks post-treatment, one continuing for more than 8 months. These patients (3 at 4.0 mg/kg dose level and 1 receiving 8.0 mg/kg milatuzumab) appeared to have higher serum levels of the anti-CD74 antibody. There have been no objective responses in 21 evaluable patients.

"This is our first clinical study of milatuzumab and we are encouraged by these results in a difficult to treat population of patients that have been heavily pretreated. Our next studies for milatuzumab may involve the doxorubicin conjugate or in combination with other agents," commented Cynthia L. Sullivan, President and CEO.

About Milatuzumab

Milatuzumab is a humanized anti-CD74 antibody constructed using the same constant regions of the heavy and light chains as epratuzumab, whose safety has been demonstrated in clinical trials of patients with B-cell malignancies and autoimmune disorders. Milatuzumab was found to block the overexpression of CD74 in chronic lymphocytic leukemia (CLL) cells which led to increased cell death. Preclinical studies have also shown that milatuzumab can inhibit the growth of human multiple myeloma (MM) and lymphoma cells in culture and in immune-depressed mice when used alone or in combination with drugs approved for the treatment of MM. Milatuzumab is being investigated as a naked antibody in 3 Phase I/II studies for the treatment of MM, non-Hodgkin's lymphoma, and CLL, and has received FDA orphan drug designation for the therapy of MM and CLL. Milatuzumab conjugated with doxorubicin will be studied in upcoming clinical trials in multiple myeloma.

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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