DENVER, April 22, 2009 (GLOBE NEWSWIRE) -- Immunomedics, Inc. (Nasdaq:IMMU), a biopharmaceutical company focused on developing monoclonal antibodies to treat cancer and other serious diseases, today reported results presented at the 100th annual meeting of the American Association for Cancer Research (AACR) that indicate CD74 is expressed at high levels in the majority of gastrointestinal tumors, which may allow milatuzumab, the Company's proprietary humanized anti-CD74 antibody, to be used as a therapy for gastrointestinal cancers, either on its own or conjugated with drugs or toxins.
CD74 is a transmembrane protein that is expressed on many cells, including B cells, T-cells and thymic epithelium. CD74 is also expressed on a variety of malignant cells including approximately 90% of B-cell cancers and certain non-hematologic malignancies, such as renal, non-small-cell lung, and thymic epithelium neoplasms, glioblastomas, and other tumors. The objective of the Company's present study was to evaluate the level of expression of CD74 in several gastrointestinal cancers.
The expression of CD74 in pancreatic cancer was high. Eighty-five percent of the specimens (48 out of 56) presenting a mostly intense, diffuse labeling pattern and an additional 9% having a moderate to intense, focal pattern. Similar results were seen with colorectal carcinomas. Of 66 colorectal carcinomas, 34 (52%) gave intense, diffuse labeling with an additional 20% having a moderate to intense focal staining pattern. For gastric cancer specimens, 57% (16 out of 28) produced the diffuse pattern and 25% the focal pattern. However, all 7 gastrointestinal stromal tumors were found negative for CD74 expression. These data suggest that CD74 is expressed at high levels in pancreatic and colorectal cancers and, as a result, milatuzumab may be effective in treating these solid tumors.
Recent scientific research has found that CD74 is involved in a cell signaling pathway for proliferation and survival. Moreover, binding of milatuzumab to the receptor blocks the pathway and leads to cell death. In a separate study presented earlier in the conference, this mechanism of action by milatuzumab was confirmed in 2 human multiple myeloma (MM) cell lines and 1 non-Hodgkin's lymphoma (NHL) cell line. The study also investigated the reactivity and cytotoxicity of milatuzumab on a panel of leukemia/lymphoma cell lines including acute lymphoblastic leukemia (ALL), acute myelogenous leukemia (AML), chronic lymphocytic leukemia (CLL), chronic myelogenous leukemia (CML), hairy cell leukemia and mantle cell lymphoma (MCL).
CD74 was found on the surface of all cell lines tested. Cytotoxicity assays demonstrated that milatuzumab was toxic to all MCL, CLL, and hairy cell leukemia cell lines, as well as 3 out of 4 ALL cell lines used in this study. Despite positive staining, however, milatuzumab had no apparent effect on all AML or CML cell lines. Thus, in addition to the activity previously seen in MM and NHL, milatuzumab also exhibits activity against a broad range of leukemias.
Commenting on these preclinical results, Cynthia L. Sullivan, President and CEO stated, "It is important for us to evaluate the level of CD74 expression in various cancers and to understand the mechanism of action of milatuzumab. We believe these studies will help us expand the range of malignancies that can be treated with this antibody."
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 is being studied clinically for the treatment of multiple myeloma, non-Hodgkin's lymphoma, and chronic lymphocytic leukemia. CD74, also known as invariant chain, has been implicated in antigen processing, particularly by dendritic and other immune cells, but recently has also been disclosed as a survival factor for rapidly proliferating malignant cells. Milatuzumab is the first anti-CD74 antagonistic antibody to enter clinical trials.
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 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, 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 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.