First T cell engaging antibody (BiTE) showing clinical benefit in cancer patients; Blinatumomab enables patients own T cells to recognize and attack cancer cells

BETHESDA, MD USA | August 14, 2008 | Micromet, Inc. (Nasdaq: MITI), a biopharmaceutical company developing novel, proprietary antibodies for the treatment of cancer, inflammation and autoimmune diseases, today announced publication of a Phase 1 clinical study(1) on its BiTE(R) antibody blinatumomab (MT103/MEDI-538) in this week’s issue of Science. The article is available at www.sciencemag.org. Blinatumomab is being co-developed with MedImmune.

Blinatumomab is a novel antibody therapy that activates a patient’s T cells to seek out and destroy cancer cells. The phase 1 study demonstrated tumor regression, and in some cases, complete remission, in non-Hodgkin’s lymphoma patients who relapsed after previous treatments and were considered to have incurable disease. Most of the remissions are reported to continue, with the longest remission ongoing for more than one year. Results from this ongoing Phase 1 clinical trial with the CD19-specific BiTE antibody blinatumomab show that all seven patients treated to date at 0.06 mg/m2 per day achieved complete or partial responses. The safety profile observed in this study supports continued blinatumomab development.

"These results represent significant progress of a T cell engaging antibody for treatment of lymphoma patients as single agent therapy. We observed tumor regression in patients at serum levels of blinatumomab, which are approximately five orders of magnitude lower than serum levels needed by conventional monoclonal antibodies for achieving a tumor regression in this disease. This may relate to the high anti-tumor activity of cytotoxic T cells recruited by blinatumomab," commented Micromet Senior Vice President and Chief Scientific Officer Patrick Baeuerle.

"This first observation of durable objective responses in relapsed, incurable patients indicates the potential blinatumomab and BiTE antibodies in general may have in fighting cancer," added Micromet Senior Vice President and Chief Medical Officer Carsten Reinhardt, M.D.

Typically antibodies cannot engage T cells because T cells lack the appropriate receptors for binding antibodies. Previous attempts have shown the potential of T cells to treat cancer, but the therapeutic approaches tested to date have been hampered by cancer cells’ ability to escape recognition by T cells. The use of antibodies that are specifically designed to engage T cells for attacking cancer cells may provide a more effective anti-tumor approach than conventional monoclonal antibodies, which require much higher doses and are typically combined with chemotherapies.

Micromet has additional clinical trials with BiTE antibodies underway, including a phase 2 clinical trial to evaluate blinatumomab for the treatment of patients with acute lymphoblastic leukemia (ALL), and a phase 1 trial investigating MT110, a BiTE antibody targeting EpCAM, in patients with lung or gastrointestinal cancers.

Micromet will host a webcast and a conference call on Monday, August 18 at 10:00 a.m. Eastern Time, (4:00 p.m. Central European Time), to discuss these results. The webcast can be accessed at: www.micromet-inc.com/sciencepub. To participate in the conference call, dial 866-202-4367 (U.S.) or 617-213-8845 (international), passcode: 31176615.

(1) Bargou R et al. (2008) Tumor regression in cancer patients by very low doses of a T cell-engaging antibody. Science 321: 974-977 (2008)

About Science

Founded in 1880 on $10,000 of seed money from the American inventor Thomas Edison, Science has grown to become the world’s leading outlet for scientific news, commentary and cutting-edge research, with the largest paid circulation of any peer-reviewed general-science journal. Through its print and online incarnations, Science reaches an estimated worldwide readership of more than one million. In content, too, the journal is truly international in scope; some 35 to 40 percent of the corresponding authors on its papers are based outside the United States. Its articles consistently rank among world’s most cited research.

About BiTE Antibodies

BiTE(R) antibodies are designed to direct the body’s cytotoxic, or cell-destroying, T cells against tumor cells, and represent a new therapeutic approach to cancer therapy. BiTE antibodies have been shown to induce an immunological synapse between a T cell and a tumor cell in the same manner as observed during physiological T cell attacks. These cytolytic synapses enable the delivery of cytotoxic proteins from T cells into tumor cells, ultimately inducing a self-destruction process in the tumor cell referred to as apoptosis, or programmed cell death. In the presence of BiTE antibodies, T cells have been demonstrated to serially eliminate tumor cells, which explains the activity of BiTE antibodies at very low concentrations and at very low ratios of T cells to target cells. Through the process of killing cancer cells, T cells proliferate, which leads to an increased number of T cells at the site of attack.

Several antibodies in Micromet’s product pipeline are BiTE antibodies and have been generated based on Micromet’s proprietary BiTE antibody platform. The most advanced BiTE antibody is blinatumomab (MT103/MEDI-538), targeting CD19, and has provided proof-of-concept in an ongoing phase 1 clinical trial in patients with advanced non-Hodgkin’s lymphoma. MT110, which is targeting EpCAM (CD326) and is the first BiTE antibody with potential applications in the treatment of solid tumors, is in a phase 1 clinical trial in patients with lung or gastrointestinal cancers. Three additional BiTE antibodies, targeting CD33, CEA and MCSP, respectively, are in preclinical development.

About Micromet, Inc.

Micromet, Inc. (www.micromet-inc.com) is a biopharmaceutical company developing novel, proprietary antibodies for the treatment of cancer, inflammation and autoimmune diseases. Four of its antibodies are currently in clinical trials, while the remainder of the product pipeline is in preclinical development. The BiTE(R) antibody blinatumomab (MT103/MEDI-538) is in a phase 2 clinical trial for the treatment of patients with acute lymphoblastic leukemia and in a phase 1 clinical trial for the treatment of patients with non-Hodgkin’s lymphoma. BiTE antibodies represent a new class of antibodies that activate a patient’s own cytotoxic T cells, considered the most powerful "killer cells" of the human immune system, to eliminate cancer cells. Micromet is developing blinatumomab in collaboration with MedImmune, Inc., a subsidiary of AstraZeneca plc. MT110 is the second BiTE antibody in clinical trials, and is being developed by Micromet in a phase 1 clinical trial for the treatment of patients with lung or gastrointestinal cancer. The third clinical stage antibody is adecatumumab, also known as MT201, a human monoclonal antibody that targets epithelial cell adhesion molecule (EpCAM)-expressing solid tumors. Micromet is developing adecatumumab in collaboration with Merck Serono in a phase 1b clinical trial evaluating adecatumumab in combination with docetaxel for the treatment of patients with metastatic breast cancer. The fourth clinical stage antibody is MT293 which is licensed to TRACON Pharmaceuticals, Inc. and is being developed in a phase 1 clinical trial for the treatment of patients with cancer. Three additional BiTE antibodies, targeting CD33, CEA and MCSP, respectively, are in preclinical development. In addition, Micromet has established a collaboration with Nycomed for the development and commercialization of MT203, a human antibody neutralizing the activity of granulocyte/macrophage colony stimulating factor (GM-CSF), which has potential applications in the treatment of various inflammatory and autoimmune diseases, such as rheumatoid arthritis, psoriasis, or multiple sclerosis.

SOURCE: Micromet Inc.