Immunomedics Reports Labetuzumab Govitecan is Active in Relapsed Metastatic Colorectal Cancer

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| Source: Immunomedics

CHICAGO, June 2, 2015 (GLOBE NEWSWIRE) -- Immunomedics, Inc., (Nasdaq:IMMU) today announced an interim analysis of a mid-stage clinical study showed that its first-in-class antibody-drug conjugate (ADC), labetuzumab govitecan, produced encouraging survival results in patients previously treated with at least one prior irinotecan-containing regimen for their metastatic colorectal cancer (mCRC).

For the 33 patients who received the ADC at the 8 or 10 mg/kg dose levels, the interim median progression-free survival (PFS), a measure of the length of time the patient is living without their disease getting worse from the beginning of their labetuzumab govitecan treatments, was 4.4 months, with 22% of these patients still benefiting from their cancer not progressing.

"Compared to what has been reported in the medical literature,1,2 this result is very encouraging for patients with mCRC," commented Dr. Efrat Dotan of Fox Chase Cancer Center, Philadelphia, PA, who presented the multicenter study at the 2015 Annual Meeting of the American Society of Clinical Oncology (ASCO) as one of the Principal Investigators.

In terms of treatment response, in 32 patients with at least one evaluation following treatments with labetuzumab govitecan at the 8 or 10 mg/kg level, 1 patient had a partial response and 24 patients reported stable disease as their best response, to give a combined disease control rate of 78%. Treatment response was evaluated in accordance with the rules set by the Response Evaluation Criteria In Solid Tumors (RECIST 1.1) using computed tomography as the imaging tool for tumor size measurements.

Labetuzumab govitecan was well tolerated by patients. At the optimal once-a-week doses of 8 and 10 mg/kg, grades 3 and 4 adverse events with occurrence of 5% or more included neutropenia (5% for both dose levels), and mild diarrhea (5% in the 8 mg/kg group only). Despite repeated dosing, no antibody against labetuzumab or its SN-38 conjugate was detected in blood samples from 74 patients over a 16-month period.

At the time of analysis, 87 patients have been enrolled to receive the ADC in the first 2 weeks of a 21-day cycle. In addition to the 8 and 10 mg/kg once-weekly dose, other dosing levels and schedule evaluated included 4, 6, 9, and 12 mg/kg, each at a frequency of twice a week.

"We have chosen the once-a-week dose of 10 mg/kg for future studies," commented Cynthia L. Sullivan, President and Chief Executive Officer of Immunomedics. "At this year's ASCO conference, we have met with key opinion leaders in colorectal cancer to discuss the future development plan for labetuzumab govitecan, either as a standalone therapy or in combination with other treatment regimes," Ms. Sullivan added.

The Company created labetuzumab govitecan by conjugating the moderately-toxic drug, SN-38, site-specifically and at a high ratio of drug to labetuzumab, a humanized antibody that recognizes the carcinoembryonic antigen (CEA; CEACAM5 or CD66e) expressed in many solid cancers, including more than 90% of colorectal cancer. SN-38 is the active metabolite of irinotecan (Camptosar), which is used to treat certain solid cancers, particularly metastatic colorectal cancers, as a part of combination therapies, so its pharmacology and properties are well-known.

In addition to Dr. Dotan, other clinical investigators participated in this multicenter trial are Dr. Steven J. Cohen, Fox Chase Cancer Center, Philadelphia, PA; Dr. Alexander N. Starodub, Indiana Health Center for Cancer Care, Goshen, IN; Dr. Jordan D. Berlin, Vanderbilt-Ingram Cancer Center, Nashville, TN; Drs. Christopher H. Lieu and Wells A. Messersmith, University of Colorado Cancer Center, Aurora, CO; Dr. Michael J. Guarino, Helen F. Graham Cancer Center & Research Institute, Newark, DE; Dr. John L. Marshall, Georgetown University Hospital, Washington, DC; and Dr. J. Randolph Hecht, UCLA Jonsson Comprehensive Cancer Center, Los Angeles, CA.

References

1. Grothey A. et al. Regorafenib monotherapy for previously treated metastatic colorectal cancer (CORRECT): an international, multicenter, randomized, placebo-controlled, phase 3 trial. Lancet 2013 Jan 26;381(9863):303-12.
2. Vincenzi B. et al. Cetuximab and irinotecan as third-line therapy in advanced colorectal cancer patients: a single centre phase II trial. Br J Cancer. 2006 Mar 27;94(6):792-7.

About Immunomedics

Immunomedics is a clinical-stage biopharmaceutical company developing monoclonal antibody-based products for the targeted treatment of cancer, autoimmune disorders and other serious diseases. Immunomedics' advanced proprietary technologies allow the Company to create humanized antibodies that can be used either alone in unlabeled or "naked" form, or conjugated with radioactive isotopes, chemotherapeutics, cytokines or toxins. Using these technologies, Immunomedics has built a pipeline of nine clinical-stage product candidates. Immunomedics has an ongoing collaboration with UCB, S.A. (UCB), to whom the Company licensed epratuzumab for the treatment of all non-cancer indications worldwide. UCB expects Phase 3 data in systemic lupus erythematosus in the first half of 2015. Immunomedics is exploring epratuzumab in oncology in collaboration with independent cancer study groups. Immunomedics' most advanced candidate to which it retains worldwide rights for all indicationsis 90Y-clivatuzumab tetraxetan. The Company initiated a Phase 3 registration trial in January 2014 in patients with advanced pancreatic cancer and expects patient enrollment to be completed in calendar year 2016. Immunomedics' portfolio of wholly owned product candidates also includes antibody-drug conjugates (ADCs) that are designed to deliver a specific payload of a chemotherapeutic directly to the tumor while reducing overall toxic effects that are usually found with conventional administration of these chemotherapeutic agents. Immunomedics' most advanced ADCs are sacituzumab govitecan (IMMU-132) and labetuzumab govitecan (IMMU-130), which are in Phase 2 trials for a number of solid tumors and metastatic colorectal cancer, respectively. Immunomedics also has a number of other product candidates that target solid tumors and hematologic malignancies, as well as other diseases, in various stages of clinical and pre-clinical development. These include bispecific antibodies targeting cancers and infectious diseases as T-cell redirecting immunotherapies, as well as bispecific antibodies for next-generation cancer and autoimmune disease therapies, created using its patented DOCK-AND-LOCK® protein conjugation technology. The Company believes that its portfolio of intellectual property, which includes approximately 267 active patents in the United States and more than 400 foreign patents, protects its product candidates and technologies. Immunomedics' strength in intellectual property has resulted in a top-8 ranking in the Biotechnology industry by the Patent Board for the 2014 fiscal year. For additional information on the Company, please visit its website at www.immunomedics.com. The information on its 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 (including the funding therefor, outcomes, timing or associated costs), 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, new product development (including clinical trials outcome and regulatory requirements/actions), our dependence on UCB for the further development of epratuzumab for non-cancer indications, risks associated with the outcome of pending litigation and 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.

Dr. Chau Cheng
Senior Director, Investor Relations & Corporate Secretary
(973) 605-8200, extension 123
ccheng@immunomedics.com