(IMMU) 90 Y-Clivatuzumab Tetraxetan With Gemcitabine Active in Late-Stage Pancreatic Cancer

LYON, France, Oct. 23, 2013 — Immunomedics, Inc. (Nasdaq:IMMU), a biopharmaceutical company primarily focused on the development of monoclonal antibody-based products for the targeted treatment of cancer, autoimmune and other serious diseases, today reported that multiple cycles of therapy with the Company’s pancreatic cancer therapeutic, clivatuzumab tetraxetan labeled with yttrium-90 (⁹⁰Y), in combination with low-dose gemcitabine, produced a median overall survival (OS) of more than 5 months in patients with metastatic pancreatic cancer who had received at least 2 prior treatments.

Results from the Phase Ib clinical trial were updated by Dr. William A. Wegener, Senior Vice President, Clinical Research, in an oral presentation at the 26^th Annual Congress of the European Association of Nuclear Medicine in Lyon, France.

Despite a difficult-to-treat patient population with relapsing disease, a partial response in 53 CT-assessable patients was reported at the Congress. In addition, median OS for patients with partial response or stable disease as best response was longer than those with disease progression (131 days vs. 66 days, respectively).

“Based on these encouraging results, which have to be confirmed with a Phase III clinical trial, we are proceeding with our plan to initiate such trial with clivatuzumab in this late-stage disease setting,” commented Cynthia L. Sullivan, President and Chief Executive Officer. “We are preparing to open this pivotal study before the end of 2013 or the beginning of 2014,” Ms. Sullivan added.

With the acronym PANCRIT, which stands for PANcreatic Cancer RadioImmunotherapy Trial, the Phase III study will be a double-blind, randomized trial of ⁹⁰Y-clivatuzumab tetraxetan with low-dose gemcitabine, versus placebo and low-dose gemcitabine in metastatic pancreatic cancer patients who have progressed on at least 2 prior therapies, 1 of which must be a gemcitabine-containing regimen.

Target enrollment for this multicenter, international trial is 440 patients. A majority of these patients will be recruited at clinical sites across the U.S., with additional sites in Canada, Europe and Israel participating. Patients will be randomized 2 to 1 to the treatment arm.

Primary endpoint of PANCRIT will be overall survival, with objective response, progression-free survival and clinical benefit such as quality of life serving as secondary outcome measures.

About Pancreatic Cancer

According to the American Cancer Society, an estimated 45,220 Americans will be diagnosed with pancreatic cancer in 2013, making it the 10^th most common cancer diagnosis among men and the 9^th most common among women in the U.S. It is, however, the fourth leading cause of cancer death among both men and women nationwide, with approximately 38,460 deaths expected, or about 7% of all cancer deaths.

The outlook for pancreatic cancer patients is bleak, with median survival ranges from 4.5 months for the most advanced stage to 24.1 months for the earliest stage. For patients with the advanced disease, treatment options are limited to gemcitabine alone or in combination with other agents. Although FOLFIRINOX, the drug combination of leucovorin, fluorouracil, irinotecan, and oxaliplatin, has recently been shown to prolong survival in patients with newly-diagnosed advanced disease, many patients could not tolerate this treatment regimen.

About Immunomedics

Immunomedics is a New Jersey-based biopharmaceutical company primarily 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, cytokines or toxins, in each case to create highly targeted agents. Using these technologies, we have built a pipeline of therapeutic product candidates that utilize several different mechanisms of action. Our lead product candidate, epratuzumab, is currently in two Phase III clinical trials in lupus. In oncology, we are planning to launch a Phase III pivotal trial for clivatuzumab labeled with a radioisotope in advanced pancreatic cancer patients. Other solid tumor therapeutics in Phase II clinical development include 2 antibody-drug conjugates, labetuzumab-SN-38 (IMMU-130) and hRS7-SN-38 (IMMU-132). We also have a majority ownership in IBC Pharmaceuticals, Inc., which is developing a novel DOCK-AND-LOCK™ (DNL™) method with us for making fusion proteins and multifunctional antibodies. DNL™ is being used particularly to make bispecific antibodies targeting cancers and infectious diseases as a T-cell redirecting immunotherapy, as well as bispecific antibodies for next-generation cancer and autoimmune disease therapies. We believe that our portfolio of intellectual property, which includes approximately 231 active patents in the United States and more than 400 foreign patents, protects our product candidates and technologies. Our strength in intellectual property has resulted in the top-10 ranking in the 2012 IEEE Spectrum Patent Power Scorecards in the Biotechnology and Pharmaceuticals category. For additional information on us, please visit our website at www.immunomedics.com. The information on our 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, 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, risks associated with any cash payment that the Company might receive in connection with a sublicense involving a third party and UCB, which is not within the Company’s control, 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, 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: Dr. Chau Cheng
         Senior Director, Investor Relations & Grant Management
         (973) 605-8200, extension 123
         ccheng@immunomedics.com