BERLIN, June 5, 2009 (GLOBE NEWSWIRE) -- Immunomedics, Inc. (Nasdaq:IMMU), a biopharmaceutical company focused on developing monoclonal antibodies to treat cancer and other serious diseases, today announced a 68% overall response rate in patients with immune thrombocytopenic purpura (ITP) treated with low doses of veltuzumab, administered either intravenously or subcutaneously. Results from this multicenter, open-label, single-arm, Phase I/II study were presented at the 14th Congress of the European Hematology Association.
The overall response rate (minor, partial and complete responses) in 19 evaluable patients was 68%, with 26% of patients having a complete response (platelets increased to over 150,000 per microL (150 x 10(9)/L) blood). Responses occurred across all doses tested, including the lowest dose at 80 mg, regardless of the route of administration. More importantly, all patients who have a complete response to veltuzumab continue to maintain their increased platelet levels, with 2 patients continuing for over 1 year. It was found that the responses began within 2-4 days after the first injection of veltuzumab.
"These encouraging results corroborate the initial findings that we reported at the annual meeting of the American Society of Hematology last December," commented Cynthia L. Sullivan, President and CEO. "The study is now entering into Phase II, where additional patients will be enrolled to receive subcutaneous injections," she added.
The goal of this first study of veltuzumab in ITP is to evaluate its efficacy at low doses. At the time of reporting, 20 adult chronic ITP patients with platelet counts below 30 x 10(9)/L who failed at least one standard therapy have been treated with 2 veltuzumab doses administered 2 weeks apart. Seven patients received the initial intravenous formulation at 1 of 3 levels: 80, 120 or 200 mg. One patient had an infusion reaction and discontinued treatment. Thirteen patients received subcutaneous injections of veltuzumab at 1 of 3 levels: 80, 160 or 320 mg. The injections were well tolerated with no grade 3-4 adverse events reported.
All patients were evaluated over a 12-week period, with responding patients continuing in long-term follow-up. Patients with platelet levels higher than 150 x 10(9)/L measured on 2 separate occasions, at least 1 week apart, were classified as complete responders. Those with measurements between 50-150 x 10(9)/L were considered partial responders, and minor responses were between 30-50 x 10(9)/L.
Both routes of veltuzumab administration produced B-cell depletion, even at the lowest dose of 80 mg. Two patients had a minor immunogenic response to veltuzumab following intravenous infusions, with no clinical after-effects.
About ITP
ITP is an autoimmune disease in which the immune system attacks the platelets (or thrombocytes) resulting in their accelerated destruction. It is a bleeding disorder characterized by low blood platelet counts of less than 50 x 10(9)/L. The incidence of adult ITP is approximately 10 - 125 cases per 1,000,000 per year, and predominantly affects females with onset between 18 to 40 years of age. Treatment is usually required for platelet levels below 30 x 10(9)/L because of high risk of bleeding. Conventional initial therapy is corticosteroids with or without intravenous immunoglobulins, but many patients relapse when steroids are tapered. Standard treatment in this situation has been splenectomy, which results in durable complete remission in 60 - 70% of cases. For patients who do not respond to corticosteroids, immunoglobulins, or splenectomy, the FDA has recently approved two new agents that mimic thrombopoietin, the major platelet growth factor that stimulates the production of platelets by the bone marrow.
About Veltuzumab
As a second generation humanized anti-CD20 antibody, veltuzumab was constructed using the same human donor frameworks as epratuzumab, the Company's humanized anti-CD22 antibody. Consequently, similar to epratuzumab, veltuzumab can be infused relatively rapidly and has been well tolerated by patients. Veltuzumab's complementarity-determining regions (CDRs) are identical to rituximab, except for one amino acid residue (aspartic acid instead of asparagine) in CDR3's heavy chain variable region. Veltuzumab demonstrated slower off-rates in three human lymphoma cell lines, and mutation studies confirmed that the difference was related to the single amino acid change. Although antiproliferative, apoptotic, and antibody-dependent cellular cytotoxicity effects seemed similar in vitro, veltuzumab demonstrated increased complement-dependent cytotoxicity in one of three lymphoma cell lines and was significantly more effective in vivo than rituximab in three human lymphoma models. Even at low doses, veltuzumab effectively depleted B cells in cynomolgus monkeys and controlled tumor growth in mice bearing human lymphoma xenografts. Immunomedics' partner Nycomed was granted the worldwide rights to develop, manufacture and commercialize the subcutaneous formulation of veltuzumab for the treatment of all non-cancer indications.
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.