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Immunomedics Reports Complete Responses in Patients With Metastatic Triple-Negative Breast Cancer After Sacituzumab Govitecan Treatment

CHICAGO, June 1, 2015 (GLOBE NEWSWIRE) -- Immunomedics, Inc., (Nasdaq:IMMU) today announced that among 49 patients with metastatic triple-negative breast cancer (TNBC) evaluated for response to treatments with sacituzumab govitecan in a mid-stage clinical study, 31%, or 15 patients, showed a reduction in tumor size of 30% or more. They include 2 patients with complete response. Response assessments were based on the rules set by the Response Evaluation Criteria In Solid Tumors (RECIST 1.1). Adding the 22 patients with responses between less than 30% tumor shrinkage and less than 20% tumor increase, the disease control rate was 76%.

Sacituzumab govitecan also produced significant duration of response in these responding patients. Measured as the time it takes from the beginning of sacituzumab govitecan treatments to when the cancer progresses, the median progression-free survival (PFS) for the 48 patients who received the optimal doses of 8 or 10 mg/kg was 6.0 months. Importantly, 63% of patients (22 of 35) had a time-to-progression longer than their last therapy, notwithstanding disease progression has not yet happened in 56% of patients at the time of analysis.

These results were presented at the 2015 Annual Meeting of the American Society of Clinical Oncology by Dr. Aditya Bardia of Massachusetts General Hospital Cancer Center in Boston, MA, and a faculty member at Harvard Medical School, who commented, "Given that a majority of the patients enrolled into this study had failed 4 or more prior cancer therapies, some as many as 11, we are quite encouraged with sacituzumab govitecan in this late-stage setting in an aggressive disease that is difficult to treat."

As the name implies, TNBC represents breast cancers that are negative for estrogen and progesterone receptors, as well as human epidermal growth factor receptor 2, or HER2. This type of breast cancer comprises about 15-20% of all invasive breast cancers and is more prevalent in young and African-American women. Despite the fact that initial responses with chemotherapy are high, TNBC characteristically has a high recurrence rate and is perhaps the most difficult type of breast cancer to treat successfully with current cytotoxic agents. Progression-free survival in the range of 2.9 – 3.7 months has been reported in recent clinical studies in patients with metastatic TNBC following chemotherapy.1-3 Currently, there are no targeted treatments available for TNBC.

A total of 58 patients with relapsed or refractory metastatic TNBC have been enrolled into the multicenter study to receive sacituzumab govitecan once a week for 2 weeks in 21-day cycles. Despite repeated dosing, sacituzumab govitecan was well tolerated by patients. At the optimal doses of 8 and 10 mg/kg, transient neutropenia was the major Grade 3 or 4 adverse events with 26% occurrence. Grade 3 diarrhea was minimal, reported by only 2% of patients.

Commenting on these encouraging results, Ms. Cynthia L. Sullivan, President and Chief Executive Officer of Immunomedics stated, "We plan to advance the agent to a Phase 3 registration trial, the design of which is being discussed with the regulatory authorities and key opinion leaders." "Our ultimate goal is to develop the full potential of this important and valuable asset for the benefits of cancer patients by advancing it with a corporate partner," Ms. Sullivan reiterated.

Sacituzumab govitecan is a first-in-class antibody-drug conjugate (ADC) developed by the Company by conjugating the moderately-toxic drug, SN-38, site-specifically and at a high ratio of drug to antibody to a humanized antibody that targets the TROP-2 receptor expressed by many solid cancers. 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.

The U.S. Food and Drug Administration has designated sacituzumab govitecan a Fast Track development program for the treatment of patients with TNBC who have failed prior therapies for metastatic disease and patients with small-cell or non-small cell lung cancers.

Dr. Steven J. Isakoff, a colleague of Dr. Bardia at Massachusetts General Hospital, also participated in this multicenter study. Other Principal Investigators include Drs. Linda T. Vahdat and Allyson J. Ocean, Weill Cornell Medical College, New York, NY; Drs. Jennifer R. Diamond and Wells A. Messersmith, University of Colorado Cancer Center, Aurora, CO; Dr. Alexander N. Starodub, Indiana University Health Center for Cancer Care, Goshen, IN; Drs. Rebecca L. Moroose and Sajeve S. Thomas, UF Health Cancer Center, Orlando, FL; and Drs. Jordan D. Berlin and Ingrid A. Mayer, Vanderbilt-Ingram Cancer Center, Vanderbilt University, Nashville, TN.

References

1. O'Shaughnessy J. et al. Phase III study of iniparib plus gemcitabine and carboplatin versus gemcitabine and carboplatin in patients with metastatic triple-negative breast cancer. J Clin Oncol. 2014 Dec 1;32(34):3840-7.

2. Forero-Torres A. et al. TBCRC019: Phase II trial of nab-PAC with/without the anti-death receptor 5 monoclonal antibody tigatuzumab in patients with triple negative breast cancer. Clin Cancer Res. 2015 Mar 16. pii: clincanres.2780.2014. [Epub ahead of print].

3. Isakoff S.J. et al. TBCRC009: A multicenter Phase II clinical trial of platinum monotherapy with biomarker assessment in metastatic triple-negative breast cancer. J Clin Oncol. 2015 Apr 6. pii: JCO.2014.57.6660. [Epub ahead of print].

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 indications is 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.

CONTACT: For More Information: Dr. Chau Cheng Senior Director, Investor Relations & Corporate Secretary (973) 605-8200, extension 123 ccheng@immunomedics.comSource:Immunomedics, Inc.