Immunomedics Reports Progress With Labeling Proteins, Including Antibodies, for Improved PET Imaging

VANCOUVER, British Columbia, June 12, 2013 (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 progress with labeling temperature-sensitive molecules using fluorine-18 (¹⁸F) for improved positron-emission tomography (PET) imaging of diseases. Results of this study were presented by William McBride, Ph.D., Senior Director, Peptide Chemistry.

The Company previously published a novel method of radiolabeling peptides with ¹⁸F known as AlF.¹ Eleven publications have since tracked the development of this patented method, including a recently published review.² The Company simplified the approach with the development of a lyophilized kit that permits the radiolabeling of peptides within about 20 minutes, with yields exceeding 70% and high specific activity.³ A similar radiolabeling kit utilizing the AlF technology was recently validated clinically by National Institute of Health scientists, in collaboration with Chinese physicians, who successfully imaged all sites of tumor in 9 lung cancer patients with a ¹⁸F-labeled peptide.⁴ More importantly, as recently reported by us (http://www.immunomedics.com/pdfs/news/2013/pr05282013.pdf), this method is now protected by 11 U.S. issued patents.

¹⁸F labeling by the AlF procedure requires the use of metal-binding ligands, such as NODA or NOTA, which capture a highly stable aluminum-¹⁸F complex. The Company previously reported the creation of the NODA-MPAA ligand for highly efficient direct radiolabeling of peptides and other compounds that can withstand high temperatures, and introduced a 2-step procedure that could be used for radiolabeling heat-sensitive compounds, such as antibody fragments. (For more information, please visit the Company's press release at http://www.immunomedics.com/pdfs/news/2011/pr06082011.pdf).

The current study presented at this year's SNMMI Annual Meeting was aimed at creating new NODA-based ligands for improved radiofluorination yields at lower temperatures. Two new ligands, a pyridine-NODA and a triazole-NODA, were synthesized and shown to have higher labeling yields than NODA-MPAA, especially at lower temperatures. Furthermore, no co-solvent was needed for the peptide linked with triazole-NODA ligand. Both of the F-18-labeled peptides were stable in human serum at 37^oC for at least 4 hours.

In a second oral presentation at this year's SNMMI Annual Meeting, Shankar Vallabhajosula, Ph.D., Nuclear Medicine/Molecular Imaging, Weill Cornell Medical College, New York, NY, reported progress toward the commercial development of radiopharmacy manufacturing to prepare multi-dose ¹⁸F labeled peptides and proteins using the Company's patented AlF-labeling method. Their new study evaluated processes aimed at optimizing the radiolabeling procedure for multi-dose preparation of IMP485, a hapten-peptide used for pretargeting, a highly sensitive and specific method for targeting cancers using a bispecific antibody.⁵

The optimized procedure had 60% yields, with specific activity high at 5.1 Ci (137.8 GBq)/μmole. Sep-Pak purification resulted in >90% radiochemical purity (RCP) and HPLC purification was not required. The investigators further found that a widely used and simple procedure known as instant thin-layer chromatography (ITLC) using silicon gel and water was suitable for the assessment of RCP. Using these procedures, ¹⁸F-IMP-485 may be an ideal radiopharmaceutical for ImmunoPET studies based on the pretargeting approach pioneered by the Company.

This study was supported in part by Award Number R44RR028018 from the National Center for Research Resources and the National Institute of Biomedical Imaging and Bioengineering of the National Institutes of Health.

Reference

1. McBride W.J., Sharkey R.M., Karacay H., D'Souza C.A., Rossi E.A., Laverman P., Chang C.H., Boerman O.C., Goldenberg D.M. A novel method of 18F radiolabeling for PET. J Nucl Med. 2009 Jun;50(6):991-8. doi: 10.2967/jnumed.108.060418. Epub 2009 May 14.
    
2. McBride W.J.,Sharkey R.M.,Goldenberg, D.M. Radiofluorination using aluminum-fluoride (Al18F). EJNMMI Research 2013 May 8;3(1):36. doi:10.1186/2191-219X-3-36.
    
3. McBride W.J., D'Souza C.A., Karacay H., Sharkey R.M., Goldenberg D.M. New lyophilized kit for rapid radiofluorination of peptides. Bioconjug Chem. 2012 Mar 21;23(3):538-47. doi: 10.1021/bc200608e. Epub 2012 Feb 10.
    
4. Wan W., Guo N., Pan D., Yu C., Weng Y., Luo S., Ding H., Xu Y., Wang L., Lang L., Xie Q., Yang M., Chen X. First experience of 18F-alfatide in lung cancer patients using a new lyophilized kit for rapid radiofluorination. J Nucl Med. 2013 May;54(5):691-698. doi: 10.2967/jnumed.112.113563. Epub 2013 April 3.
    
5. Goldenberg D.M., Chang C.H., Rossi E.A., McBride W.J., Sharkey R.M. Pretargeted molecular imaging and radioimmunotherapy. Theranostics. 2012; 2(5):523-40. doi: 10.7150/thno.3582. Epub 2012 May 17.

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™) method 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 223 active patents in the United States and more than 400 foreign patents, protects our product candidates and technologies. Our strength in intellectual property has resulted in the top-10 ranking in the 2012 IEEE Spectrum Patent Power Scorecards in the Biotechnology and Pharmaceuticals category. 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, potential collaborations, 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 any cash payment that the Company might receive in connection with a sublicense involving a third party and UCB, which is not within the Company's control, new product development (including clinical trials outcome and regulatory requirements/actions), our dependence on our licensing partners for the further development of epratuzumab 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.