Initial results indicate encouraging activity for both rituximab-refractory and -responsive disease

WALTHAM, MA, USA | December 7, 2009 | ImmunoGen, Inc. (Nasdaq: IMGN), a biopharmaceutical company that develops targeted anticancer therapeutics, today announced the presentation of encouraging initial clinical findings with SAR3419 at the American Society of Hematology (ASH) 51st Annual Meeting and Exposition. Among the findings reported were responses to SAR3419 – administered as a single agent – among patients with B-cell non-Hodgkin’s lymphoma that is refractory to treatment with rituximab (Rituxan®).

SAR3419 is an investigational compound designed to target and kill cancer cells that express the protein, CD19, on their surface. The compound is in development by sanofi-aventis for the treatment of relapsed/refractory CD19-expressing non-Hodgkin’s lymphoma and other B-cell malignancies. ImmunoGen created SAR3419 using its Targeted Antibody Payload (TAP) technology and licensed it to sanofi-aventis as part of a broader collaboration.

The study found that 17 of 27 (63%) patients who were response-evaluable at the time of data cut-off for presentation experienced a reduction in tumor size (7% to 86% reduction). These included 7 of 14 (50%) patients who had disease that was refractory to treatment with rituximab.

Five patients had an objective response, all of whom received SAR3419 at its maximum tolerated dose (MTD) or the next highest or lowest dose. Among these responders was a patient with rituximab-refractory disease. All but one of these five patients reached the best response either during the last treatment cycle allowed under the study protocol (cycle 6) or after their last dose of SAR3419. This is consistent with the observation that the best response to treatment typically occurred after a patient had received several doses of SAR3419.

A primary endpoint of the study was to establish the MTD of SAR3419 when administered once every three weeks. This was determined to be 160 mg/m2. Additional patients will receive SAR3419 at this dose to gain more information on the tolerability and activity of the compound when administered at its MTD. A Phase I study also is underway to assess weekly dosing of SAR3419.

“These initial findings support that SAR3419 offers potential for the treatment of B-cell non-Hodgkin’s lymphoma, including rituximab-refractory disease,” commented John Lambert, PhD, Executive Vice President and Chief Scientific Officer, ImmunoGen. “SAR3419 has demonstrated evidence of activity at doses that were well tolerated. Of particular note, the compound wasn’t associated with toxicities that would limit its ability to be evaluated as part of a combination regimen in future studies, if desired. We look forward to seeing the findings from the expansion phase of this trial as well as from the weekly-dosing study.”

About the Presentation

The presentation, “Phase I Multi-Dose Escalation Study of the Anti-CD19 Maytansinoid Immunoconjugate SAR3419 Administered by Intravenous (IV) Infusion Every 3 Weeks to Patients with Relapsed/Refractory B-Cell Non-Hodgkin’s Lymphoma (NHL)” (abstract #585) was given by Anas Younes, MD, Professor of Medicine and Director, Clinical Investigation and Translational Research, Department of Lymphoma/Myeloma at the MD Anderson Cancer Center.

About the Study

Patients received SAR3419 by intravenous infusion once every 3 weeks at dose levels ranging from 10-270 mg/m2. The dose-limiting toxicity was found to be manageable and reversible corneal toxicity. SAR3419 was generally well-tolerated and was not associated with any significant hematological toxicity that would limit its ability to be used in combination with other agents.

A total of 38 patients had been enrolled at the time of data cut-off for presentation. These patients all had CD19-expressing B-cell non-Hodgkin’s lymphoma that had either returned following treatment (relapsed) or was unresponsive to treatment (refractory). Seventeen of these patients had follicular lymphoma, 10 had small lymphocytic lymphoma, 5 had mantle cell lymphoma, 2 had marginal zone lymphoma and 4 had diffuse large B-cell lymphoma. They all had received prior treatment with rituximab, a monoclonal antibody that targets B-cells expressing CD20. Nine patients had undergone stem cell transplantation after prior drug and/or radiation therapy. There were no restrictions on the number or types of prior treatment regimens the patients may have received.

About Non-Hodgkin’s Lymphoma

Non-Hodgkin’s lymphoma is a cancer that starts in lymphocytes, a type of white blood cell which is part of the body’s immune system. Non-Hodgkin’s lymphoma can occur at any age and is often marked by enlarged lymph nodes, fever, and weight loss. There are many different types of non-Hodgkin’s lymphoma. These types can be divided into aggressive (fast-growing) and indolent (slow-growing) types, and they can be formed from either B lymphocytes (B-cells) or T lymphocytes (T-cells). Lymphomas that occur after bone marrow or stem cell transplantation are usually B-cell non-Hodgkin’s lymphomas. Although both B and T lymphocytes can develop into lymphoma cells, B-cell lymphomas are much more common than T-cell lymphomas, and make up about 85 percent of non-Hodgkin’s lymphomas diagnosed in the US. Prognosis and treatment of non-Hodgkin’s lymphomas depend on the stage and type of disease.

In 2009, about 453,000 people are living with non-Hodgkin’s lymphoma or are in remission. It is estimated that approximately 66,000 new cases of non-Hodgkin’s lymphoma will be diagnosed in the US this year, and 19,500 people will die from the disease.

About ImmunoGen, Inc.

ImmunoGen, Inc. develops targeted anticancer therapeutics using its expertise in cancer biology, monoclonal antibodies and the creation and attachment of potent cancer-cell killing agents. The Company’s Targeted Antibody Payload (TAP) technology uses antibodies to deliver one of ImmunoGen’s proprietary cancer-cell killing agents specifically to tumors. In addition to the Company’s product pipeline, compounds utilizing the TAP technology are in clinical testing through ImmunoGen’s collaborations with Genentech (a wholly-owned member of the Roche Group), sanofi-aventis, Biogen Idec and Biotest. The most advanced compound, trastuzumab-DM1 (T-DM1), is in Phase III testing being conducted by Genentech and Roche. Other ImmunoGen collaborative partners include Bayer HealthCare and Amgen. More information about ImmunoGen can be found at www.immunogen.com.

SOURCE: ImmunoGen, Inc.