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Immunomedics Reports Durable Responses in Patients With Advanced Solid Cancers After Therapy With Sacituzumab Govitecan

SAN DIEGO, Oct. 19, 2015 (GLOBE NEWSWIRE) -- Immunomedics, Inc., (Nasdaq:IMMU) today announced that sacituzumab govitecan, the Company's lead investigational antibody-drug conjugate (ADC), produced durable responses that exceeded one year in some patients with metastatic triple-negative breast (TNBC), small-cell (SCLC) and non-small-cell lung (NSCLC) cancers. In other patients with less than 1 year of response duration, their responses are continuing.

Dr. David M. Goldenberg, Chairman, Chief Scientific Officer and Chief Patent Officer, presented the results at the 2015 World ADC San Diego conference. The presentation on TNBC focused on those patients who relapsed after 2 or more prior lines of therapy that included taxane, a class of chemotherapy agents used to treat solid cancers, such as breast, gastric, head and neck, lung, ovarian, pancreatic, and prostate. At the time of this analysis, 56 enrolled patients had received sacituzumab govitecan at the optimal dose of 10 mg/kg given on days 1 and 8 of a 3-week cycle, and in some patients the therapy continued for many months. The median number of prior lines of therapy for the patients enrolled with metastatic TNBC was 5 (range, 2 – 12).

Treatment response, assessed by computed tomography (CT) according to the rules set by the Response Evaluation Criteria In Solid Tumors (RECIST 1.1), was available for 52 patients. The objective response rate was 29% (15/52), with 2 confirmed complete responses. The interim median progression-free survival (PFS), a measure of time patients are living without their cancer progressing, was 7.0 months, which appears to be longer than the best PFS results in this patient setting achieved by currently-used agents. Forty-six percent of these TNBC patients had experienced a PFS event. Overall survival (OS) data were too early to report because 86% of patients are still alive.

For metastatic lung cancers, a total of 33 patients with NSCLC, having received a median of 3 (range, 1 – 7) prior therapies, were enrolled to receive sacituzumab govitecan at the 8.0 mg/kg or 10 mg/kg dose level. Among the 29 patients that were assessable, an objective response (partial response) rate of 28% (8/29) was observed, including patients with both squamous cell and adenocarcinoma NSCLC types. For the 25 patients at the 10 mg/kg dose, the interim median PFS was 3.8 months, with 48% of patients in this dose group having experienced a PFS event.

In SCLC, of the 27 patients, with a median of 3 prior therapies (range 1 – 5), enrolled at the doses of 8.0 mg/kg and 10 mg/kg, 25 were assessable for response. Six patients achieved a partial response (objective response rate = 24%). Interim median PFS for the 12 patients at the 10 mg/kg dose level was 3.6 months and 83% of patients had experienced a PFS event. Since 96% of NSCLC patients and 100% of SCLC patients were still alive at the time of analysis, OS data at the optimal dose of 10 mg/kg are too early to report.

Dr. Goldenberg also presented results, for the first time, on 15 patients with metastatic urothelial cancers, mostly urinary bladder cancers. At the time of analysis, 6 of 11 patients who relapsed to a prior platinum-containing therapy and evaluable by CT achieved a partial response (objective response rate = 55%), with 5 patients still continuing treatment.

Sacituzumab govitecan continues to demonstrate a highly tolerable safety profile. Among the 261 patients enrolled to-date, only 8 patients had reported adverse events that temporarily interrupted the infusion. In the 118 patients receiving the ADC at the dose of 10 mg/kg, the major toxicity reported was Grades 3 or 4 neutropenia in 20% of patients.

"These efficacy and safety results reaffirm the high therapeutic index of sacituzumab govitecan in TROP-2-expressing solid cancers, which, we believe, distinguishes it from other ADCs approved or in development," remarked Cynthia L. Sullivan, President and Chief Executive Officer. "The Phase 2 study will be further updated at the AACR-NCI-EORTC International Conference on Molecular Targets and Cancer Therapeutics in November, and the San Antonio Breast Cancer Symposium in December," Ms. Sullivan added.

Ms. Sullivan further commented, "We continue to advance our regulatory preparations with the FDA to move sacituzumab govitecan to a Phase 3 registration trial in patients with late-stage, metastatic TNBC, while we also focus on our business development activities for this agent. We will continue to expand our studies in patients with metastatic NSCLC, SCLC, and urothelial cancer. We believe this novel ADC will also show important activity in other cancer types, based on preclinical and early clinical results."

Sacituzumab govitecan is a first-in-class 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. The ADC has received Fast Track designation from the FDA for the treatment of patients with TNBC, SCLC and NSCLC, and has also been designated an orphan drug for the treatment of patients with SCLC or pancreatic cancer in the U.S., and for the treatment of patients with pancreatic cancer in the European Union.

About Triple-Negative Breast Cancer (TNBC)

TNBC is a serious disease, with an annual incidence estimated to be about 40,000 people, 20,000 for metastatic TNBC (mTNBC), in the United States, and with a median survival of 10-13 months and median PFS of 2-3 months for mTNBC. mTNBC is insensitive to most of the available targeted therapies for breast cancer treatment, including HER2-directed therapy (such as trastuzumab), and endocrine therapies (such as tamoxifen or the aromatase inhibitors). There is currently no single standard chemotherapy to treat patients with relapsed/refractory mTNBC. Duration of response is usually short, with rapid relapse, and visceral and brain metastases are very common. In second-line therapy and later, most chemotherapeutics have shown a PFS of up to 3.5 months.

About Non-Small-Cell Lung Cancer (NSCLC)

Estimated new cases and deaths from lung cancer (NSCLC and SCLC combined) in the United States in 2015 are 221,200 and 158,040 respectively. Lung cancer is the leading cause of cancer-related mortality in the United States. All patients with advanced or metastatic NSCLC either relapse or die. More than 60,000 patients die in the U.S. each year from squamous NSCLC, which is more than the annual deaths from breast cancer and colon cancer combined. The proven benefit of third-line treatment in advanced NSCLC is still unclear. The PFS after third-line therapy is approximately 2 to 3 months. Monotherapy is recommended in third-line treatment. Currently, only erlotinib is registered for this indication. This treatment is only indicated for patients who have not yet received EGFR TKIs regardless of the performance status. Recently, two checkpoint-inhibiting antibodies targeting PD-1 have been approved in patients with advanced NSCLC.

About Small-Cell Lung Cancer (SCLC)

SCLC is a histologic subtype of lung cancer with a distinct biology, treatment regimens, and patient population. It accounts for approximately 15% of bronchogenic carcinomas. Median survival is measured in months when untreated, and the 5-year survival rate is in the range of 4-5%. Thus, there is a tremendous need for new therapies that can be given to patients after failing initial therapy, and initial chemotherapy for metastatic disease is unsatisfactory. These patients relapsing after a platinum-containing therapy have a median survival of only 4 to 5 months. Single-agent topotecan is approved by the FDA as a subsequent therapy for patients with SCLC and leads to a survival of only 16 to 21 weeks, and an overall response rate of 2-7% in platinum-refractory patients.

About Urothelial Cancer

Urothelial bladder carcinoma (UC) is the sixth most frequent cancer. Cisplatinum-based combination chemotherapy is the only known therapy that has demonstrated a survival benefit for patients with advanced disease. Unfortunately, only a small subset will attain long-term survival. For those participating in clinical trials, the median overall survival is 15 months and the five-year survival is only 15%. Following progression within 6-12 months of platinum-based chemotherapy (platinum-resistant urothelial carcinoma), whether delivered in the peri-operative or advanced setting, survival is only 4-9 months for those eligible for clinical trials and no therapy is approved in the U.S., with only vinflunine being approved in Europe. Developing effective second-line therapies for advanced urothelial cancer represents an important unmet medical need.

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' most advanced candidate is 90Y-clivatuzumab tetraxetan. The radiolabeled antibody is in a Phase 3 registration trial in patients with advanced pancreatic cancer. Immunomedics expects patient enrollment to be completed in calendar year 2016. Immunomedics' portfolio of investigational products 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 has licensed epratuzumab to UCB, S.A., (UCB) for the treatment of all autoimmune disease indications worldwide. In oncology, Immunomedics has a research collaboration with Bayer to study epratuzumab as a thorium-227-labeled antibody. Immunomedics has other ongoing collaborations in oncology with independent cancer study groups. The IntreALL Inter-European study group is conducting a large, randomized Phase 3 trial combining epratuzumab with chemotherapy in children with relapsed acute lymphoblastic leukemia at clinical sites in Australia, Europe, and Israel. 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 preclinical 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 272 active patents in the United States and more than 400 foreign patents, protects its product candidates and technologies. 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.