Primezone Media Network
June 2, 2008
CHICAGO -- Immunomedics, Inc., a biopharmaceutical company focused on developing monoclonal antibodies to treat cancer and other serious diseases, today announced that epratuzumab labeled with the potent radioisotope, yttrium-90 (Y-90), produced significant clinical results when given in small fractionated doses repeatedly to patients with non-Hodgkin's lymphoma (NHL) in a multicenter, open-label, dose escalation study.
The study has completed its targeted enrollment of 64 adult patients with documented B-cell NHL who had failed one or more regimen therapies, including rituximab. At the time of reporting, 61 patients were evaluable with an overall objective response rate of 64% and a complete response rate of 49%. Complete responses appear durable with 15 patients remaining disease free for more than 1 year, including 5 continuing for 2-4 years. Both the objective and complete response rates appear to increase with higher cumulative doses. Sixteen patients were treated at the highest fractionated dose level, resulting in 37.5-40 mCi/m(2) total Y-90 administered in two or three doses. The overall objective response rate for this group was 100%, and the complete response rate was 75%. Importantly, responses to the RAIT were seen in patients with different types of NHL, in both rituximab-naive and treated patients, and in the subgroup of patients who had failed to respond to their last therapy, had bulky disease, and elevated lactic dehydrogenase.
"This study, we believe, has validated the concept of fractionated RAIT. By splitting the radioactive dose over two or three fractions, we have demonstrated that higher radioactivity can be delivered selectively and locally to lymphoma cells without simultaneously increasing the bone marrow toxicity normally associated with RAIT. The 45 mCi/m(2) Y-90 cumulative dose level reported in this study is more than two-fold higher than the maximum allowable dose of 32 mCi currently approved for ibritumomab tiuxetan," commented Cynthia L. Sullivan, President and Chief Executive Officer. "We are in the process of formulating a strategy for further development of this agent," she added.
In an earlier poster presentation today, the Company presented results from an ongoing Phase II study evaluating the toxicity and efficacy in patients receiving a repeated RAIT with iodine-131-labeled (I-131) labetuzumab, the Company's humanized antibody against the carcinoembryonic antigen, following salvage resection of liver metastasis of colorectal cancer.
Forty colorectal cancer patients with liver metastasis were screened for cancer by PET and CT scans. After surgery to remove liver metastases, all patients were treated with 40-50 mCi/m(2) I-131-labetuzumab. Following re-staging with PET and CT scans, 29 patients received a second RAIT treatment. All 40 patients received follow-up staging, which found no suspicious lesions in 23 patients (the adjuvant group), while 17 patients showed lesions suspicious of minimal residual or new malignant disease (the non-adjuvant group).
At the time of reporting, 57% of the patients in the adjuvant group remained disease-free, while in the non-adjuvant group only 24% reported no cancer relapse. In terms of overall survival, 91% of the adjuvant group are still alive, which has surpassed the results obtained from the first RAIT trial in which a single I-131 labeled labetuzumab application produced a 70% survival rate. In the non-adjuvant patients, the overall survival rate is 77%.
Commenting on this study, Dr. Torsten Liersch, from the Department of General Surgery, University of Gottingen, Germany and lead investigator stated, "Based on this second Phase II trial, which employed rigorous post liver resection staging with PET and CT scans, we believe it is important to continue using these imaging studies in a multicenter trial in order to better define truly adjuvant patients." "Given that there is at present no established adjuvant therapy to improve survival in colorectal patients following resection of liver metastases, we plan to initiate a randomized, multi-treatment, multicenter trial evaluating the efficacy of repeated RAIT with I-131-labetuzumab," he concluded.
About Immunomedics
Immunomedics is a New Jersey-based biopharmaceutical company 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.
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