Immunomedics Reports Updated Results From Phase I Pretargeting Therapy Study in Colorectal Cancer

Immunomedics, Inc. IMMU today announced that three studies involving two bispecific antibodies created by the Company's patented protein conjugation method, Dock-and-Lock (DNL), were presented at the 2012 Annual Meeting of the Society of Nuclear Medicine (SNM). All three presentations were pretargeting studies conducted by the Company's collaborators at the Department of Nuclear Medicine, Radboud University Nijmegen Medical Center, Nijmegen, The Netherlands. Phase I Clinical Study of Pretargeted Radioimmunotherapy in Patients with Colorectal Cancer: An Update Pretargeted radioimmunotherapy (PRIT) was investigated in this Phase I trial in patients with advanced colorectal cancer (CRC) using TF2, a DNL-bispecific antibody that binds to the carcinoembryonic antigen (CEA or CEACAM5), and the peptide IMP288. The safety, dosimetry and tumor targeting, as well as the therapeutic potential of this pretargeting system were assessed. Four cohorts of 5 patients were enrolled in this study to receive an imaging cycle with TF2 and indium-111-labeled IMP288, followed by PRIT with TF2 and IMP288 labeled with the therapeutic radioisotope lutetium-177 (177Lu). Two dose levels of TF2 (75 and 150 mg) and IMP288 (25 and 100 microgram), as well as the effect of the interval between TF2 and IMP288 administration were evaluated. Rapid tumor localization of radiolabeled IMP288 in CRC patients was seen within 1 hour post-injection of the peptide, with excellent tumor-to-normal tissue ratios of greater than 20 at 24 hours. Because TF2 was found to quickly clear from the blood, a short interval between TF2 and IMP288 is preferred. At the time of reporting, no objective therapeutic responses were observed with a single therapy.