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Antibody-Directed Radiation Therapy Appears to Improve Response to Standard-of-Care for Aggressive Lymphoma

/ Source: GlobeNewswire
  • Preliminary Results from Phase II Study of Yttrium-90-labeled Epratuzumab as Consolidation Treatment for Diffuse Large B-cell Lymphoma Reported at 2011 Annual Meeting of Society of Nuclear Medicine
  • Preclinical Results from Pretargeting of Prostate Cancer with Internalizing Bispecific Antibody also Presented

SAN ANTONIO, June 7, 2011 (GLOBE NEWSWIRE) -- Immunomedics, Inc. (Nasdaq:IMMU), a biopharmaceutical company primarily focused on the development of monoclonal antibody-based products for the targeted treatment of cancer, autoimmune and other serious diseases, today reported that smaller doses of epratuzumab labeled with yttrium-90 (90Y) given repeatedly to elderly patients with diffuse large B-cell lymphoma (DLBCL) appears to improve their response to the combination of rituximab and CHOP chemotherapy (R-CHOP), the standard of care for this disease.

DLBCL is an aggressive non-Hodgkin's lymphoma (NHL) and is the most common type, with approximately 20,000 new patients diagnosed each year in the United States. Although the standard therapy for DLBCL is R-CHOP, elderly patients who fail R-CHOP have a poor outcome, with a median survival after progression of only 0.7 months.

Epratuzumab is a humanized anti-CD22 antibody developed by Immunomedics for the treatment of B-cell mediated cancers and autoimmune diseases. Previous clinical studies have demonstrated that repeated administration of smaller doses of 90Y-epratuzumab (fractionated RAIT) produced high rates of durable responses in NHL patients.  

Sponsored by the French GOELAMS study group, the multicenter Phase II study evaluates the feasibility and safety of adding fractionated RAIT with 90Y-epratuzumab to R-CHOP therapy under the premise that a combination of different antibodies may have synergistic effects, given the fact that rituximab binds to a different target, the CD20 antigen. Primary end-point of the study is 2-year event-free survival.

Preliminary results from 41 patients between the ages of 60 and 80 years with stage III/IV DLBCL, or stage I and II disease with large tumor mass of at least 7 cm, were reported at the Annual Meeting. Patients who were candidates for stem-cell transplant were not eligible for enrollment into this study. 

After 6 cycles of R-CHOP therapy, 21 of 31  patients (68%) with CT evaluations reported a complete or unconfirmed complete response (CR/CRu) with 9 patients (29%) achieving a partial response (PR) and 1 patient (3%) with stable disease. 

All patients who responded to R-CHOP went on to receive two additional doses of 90Y-epratuzumab as a consolidation treatment. Six weeks after the fractionated RAIT, 4 of the 10 patients with PR or SD from R-CHOP therapy improved their remission status to CR/CRu.  The trial is now fully enrolled and further results must await evaluations from all patients, including evaluation of the durability of responses following consolidation therapy with RAIT after R-CHOP.

"These preliminary efficacy results are very encouraging," remarked Cynthia L. Sullivan, President and Chief Executive Officer of Immunomedics. "We look forward to the final results when all 75 elderly DLBCL patients who are not candidates for stem-cell transplant have been fully enrolled with sufficient follow-up," Ms. Sullivan added.

Separately, in a preclinical study, the prospects for using an internalizing bispecific antibody for pretargeting of prostate cancer were examined.

Through the use of a bispecific antibody, pretargeting is a novel method that separates the targeting antibody from the subsequent delivery of an imaging or therapeutic agent that binds to the tumor-localized antibody. The method was developed by the Company's majority-owned subsidiary, IBC Pharmaceuticals, Inc., and has the advantages of improving tumor-to-background ratios and the delivery of higher therapeutic dose selectively to tumor targets. However, internalization would limit the use of a bispecific antibody for pretargeting. 

TF12 is a bispecific antibody constructed using the Company's patented Dock-and-Lock (DNL) protein engineering platform. It specifically targets the epithelial glycoprotein-1 antigen (EGP-1 or TROP-2) expressed in many epithelial cancers, including virtually all prostate cancers, and has been reported to internalize when bound.

Biodistribution studies in mice carrying human prostate cancer cells showed that TF12 in combination with an indium-111-labeled peptide produced excellent tumor-to-blood ratios at 2 hours after injection of the radiolabeled peptide.  In addition, positron emission tomograph (PET) imaging of the tumors pretargeted with TF12 and a gallium-68-labeled peptide visualized tumors with high contrast within 1 hour of the peptide injection.  Thus, despite the internalizing properties of TF12, it is highly effective for pretargeting prostate cancer.

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, cytokines 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 178 patents issued in the United States and more than 400 foreign patents, 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.

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.

CONTACT: Dr. Chau Cheng Director, Investor Relations & Grant Management (973) 605-8200, extension 123