Phase I/II Study Results Presented at 2009 Annual Meeting of ASH
Preclinical Results With New Antibody, IMMU-114, Also Reported

NEW ORLEANS, LA, USA | December 8, 2009 | Immunomedics, Inc. (Nasdaq:IMMU – News), a biopharmaceutical company focused on developing monoclonal antibodies to treat cancer and other serious diseases, today announced that subcutaneous injections of low doses of veltuzumab in patients with non-Hodgkin’s lymphoma (NHL) achieved sustained serum levels of pharmacologically active antibody, with objective response rates comparable to those seen with higher intravenous doses.

The goal of this multicenter, open-label, Phase I/II study was to evaluate the safety, tolerability, and preliminary efficacy of subcutaneous veltuzumab in patients with previously untreated or relapsed CD20-positive indolent NHL or chronic lymphocytic leukemia (CLL). At the time of reporting, 17 NHL patients and 11 CLL patients had been enrolled to receive 4 subcutaneous injections of veltuzumab given 2 weeks apart at dose levels of 80, 160, or 320 mg. Efficacy was assessed at 4 and 12 weeks post treatment, with responding patients continuing follow-up.

In the 15 evaluable NHL patients, the objective response rate was 53%, with a complete response rate of 27%. For the 12 follicular lymphoma patients, objective and complete response rates were 58% and 25%, respectively. These results were comparable to the Phase I/II results using the intravenous formulation published by the Company (for more information, please refer to the Company’s press release at www.immunomedics.com/news_pdf/2009_PDF/PR05182009.pdf), suggesting that the subcutaneous formulation may be active against NHL. Moreover, 7 of the 8 objective responders are currently continuing in remission, now up to 6 months after treatment.

In the 9 CLL patients with response assessments available, high levels of circulating leukemic cells substantially reduced the serum veltuzumab levels. As a result, more frequent and prolonged dosing is likely required. Overall, there were no objective responses, but 5 patients (56%) showed stable disease for up to 12 weeks.

"By avoiding lengthy intravenous administration and the need for dedicated infusion suites, we believe subcutaneous injections of low-dose veltuzumab may offer benefits to both patients and the healthcare system for treatment of B-cell malignancies, and this may be particularly useful in the setting of indolent disease," said Cynthia L. Sullivan, President and CEO.

Immunomedics is collaborating with Nycomed, which received the exclusive, worldwide rights to develop, manufacture and commercialize the subcutaneous formulation of veltuzumab for the treatment of all non-cancer indications.

At the same conference, the Company also reported preclinical results of a new antibody, IMMU-114, for the therapy of B-cell malignancies. IMMU-114 is a humanized antibody targeting the HLA-DR antigen. The goals of the preclinical studies were to investigate the cytotoxic effects of IMMU-114 on leukemia, lymphoma, and multiple myeloma (MM) cell lines, as well as clinical specimens of CLL, and explore the signaling pathways involved.

Four of 6 CLL patient samples expressed HLA-DR at markedly higher levels than CD20, with the remaining 2 showing similar HLA-DR and CD20 expression. High expression of HLA-DR was also detected on the cell surface of all mantle cell lymphoma (MCL), acute lymphoblastic leukemia (ALL), hairy cell leukemia (HC), CLL, and NHL cell lines tested, as well as 2/3 acute myeloid leukemia (AML) and 5/6 MM cell lines.

Approximately 60% cytotoxicity was obtained in CLL patient cells after incubation with IMMU-114. The humanized anti-HLA-DR antibody was cytotoxic to 2/2 MCL, 2/2 CLL, 2/4 ALL, 1/1 HC, 2/2 NHL and 2/2 MM cell lines without any added crosslinking antibody. Importantly, IMMU-114 was consistently more cytotoxic than anti-CD20 antibodies on these cell lines, as well as on 2 rituximab-resistant NHL variant cell lines.

The therapeutic activity of IMMU-114 was evaluated in 3 NHL mouse models. In one model, IMMU-114 treatment yielded 100% long-term survival. Although rituximab also induced significant responses compared to untreated mice (median survival time of 87.5 vs. 36 days for untreated controls), no long-term survivors were seen. IMMU-114 was also more effective than rituximab in the other two models. Encouraged by these findings, the Company intends to introduce this new antibody into human testing.

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 141 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.

SOURCE: Immunomedics, Inc.