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ImmunoGen, Inc. Announces Encouraging Clinical Data with Its IMGN901 Compound in the Treatment of Merkel Cell Carcinoma

WALTHAM, Mass.--(BUSINESS WIRE)--Nov 17, 2009 - ImmunoGen, Inc. (Nasdaq: IMGN), a biopharmaceutical company that develops targeted anticancer therapeutics, today reported encouraging clinical data with its IMGN901 product candidate in the treatment of Merkel cell carcinoma (MCC). Meaningful evidence of anticancer activity has been noted among the limited number of patients with MCC who have received IMGN901. These findings were reported at the AACR-NCI-EORTC International Conference on Molecular Targets and Cancer Therapeutics taking place in Boston, MA, and suggest development for metastatic MCC could be a potential registration path for IMGN901.

“To date, IMGN901 has demonstrated highly encouraging activity in the treatment of Merkel cell carcinoma and has been generally well tolerated,” commented Professor Penella J. Woll, MD, PhD, Weston Park Hospital, UK. “These findings support the continued evaluation of this compound for the treatment of Merkel cell carcinoma as well as other types of CD56-expressing cancers.”

IMGN901 is designed to kill cancer cells that express CD56, a protein. It consists of a CD56-binding antibody with a potent cancer-cell killing agent, DM1, attached to it using an engineered linker. IMGN901 is a potential treatment for MCC, small-cell lung cancer, multiple myeloma, ovarian cancers and other CD56+ tumors. It is in Phase I testing for the treatment of CD56+ solid tumors and multiple myeloma. The compound is wholly-owned by ImmunoGen.

As discussed in the poster, “Clinical experience of IMGN901 (BB-10901, huN901-DM1) in patients with Merkel cell carcinoma (MCC)” (abstract #B237) presented by Professor Woll, six patients with MCC have received IMGN901 to date. All of these patients had received prior chemotherapy regimens for their cancer and entered the clinical trial, Study 002, with metastatic disease. Two of these six patients had a marked, objective response to treatment with IMGN901, while a third patient had clinically relevant stable disease for this patient population:


  • One patient had a partial response (PR) after the first IMGN901 treatment cycle and reached a complete response (CR) by the end of the third treatment cycle. This patient has been in remission for more than four years.
  • A second patient had marked tumor reduction after the first IMGN901 treatment cycle, but declined further therapy due to the occurrence of an adverse event (reversible posterior leukoencephalopathy syndrome). This patient had a confirmed PR and – based on clinical exam – has shown continued improvement in her tumors for eight months.
  • A third patient entered Study 002 with bone metastases and had previously been treated with three different combination regimens of chemotherapy. On treatment with IMGN901, this patient had stable disease that lasted for 79 days.

These findings are supported by the results to date with IMGN901 for small-cell lung cancer (SCLC). MCC and SCLC tend to be treated similarly due to commonalities in their biological characteristics, clinical course and response to treatments. Both cancers express CD56 almost universally. As reported previously, an estimated clinical benefit rate of 25% has been seen to date among patients with relapsed, metastatic SCLC receiving IMGN901.1

“We're using Study 002 to evaluate IMGN901 for Merkel cell carcinoma and other CD56-expressing solid tumors that have limited treatment options today,” stated James O'Leary, MD, Vice President and Chief Medical Officer of ImmunoGen. “The findings are being used to inform our future clinical trials with IMGN901 for the treatment of solid tumors, and we expect to have this development plan in place in the first half of 2010. Merkel cell carcinoma is of particular interest due to the highly encouraging clinical findings to date and the lack of approved treatments for this cancer. It has the potential to be a route to market for IMGN901.”

About Study 002

This Phase I trial evaluates IMGN901 in patients with CD56+ solid tumors. The compound is administered daily for three consecutive days every 21 days (one treatment cycle). During the dose-escalation phase of the trial, increasingly greater doses of IMGN901 were administered to new cohorts of patients to establish the maximum tolerated dose. This dose has been established to be 75 mg/m2/day based on the occurrence of two Grade 3 toxicities (headache/pain in back/shoulder and myalgia) at 94 mg/m2/day (approximately 6 mg/kg per 3-week cycle).

Patients are now being enrolled in the expansion phase of Study 002. This phase is designed to gain additional experience with IMGN901 when administered at its maximum tolerated dose and focuses on specific CD56+ solid tumors of interest, which include MCC, SCLC and ovarian cancers.

IMGN901 also is being evaluated for the treatment of CD56+ multiple myeloma. Study 003 evaluates the compound when used as a single agent to treat multiple myeloma that has progressed on prior therapies. The maximum tolerated dose was recently established in this trial as well, and patient enrollment is underway in the expansion phase. Study 005 evaluates IMGN901 for multiple myeloma when used in combination with lenalidomide (Revlimid®) and dexamethasone. This trial is expected to start in late 2009.

About Merkel Cell Carcinoma (MCC)

MCC is an aggressive neuroendocrine cancer of the skin that typically occurs on the head/neck, most often in individuals of European ancestry. There are approximately 800 to 1400 new cases of MCC diagnosed in the US each year, with the incidence considered to be increasing.2 Medicinal therapy is generally used with patients whose cancer has recurred following surgery and with patients who have metastases at the time of diagnosis. Metastatic disease is associated with a poor outcome, with a median survival time of 6.8 months.

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


1 Investigation of IMGN901 in CD56+ Solid Tumors: Results from a Phase I/II Trial (Study 001) and a Phase I Trial (Study 002), 13th World Conference on Lung Cancer, 2009.

2 Based on incidence data from Agelli M, 2003; Hodgson NC, 2006.

Revlimid® is a registered trademark of Celgene Corporation.

This press release includes forward-looking statements. For these statements, ImmunoGen claims the protection of the safe harbor for forward-looking statements provided by the Private Securities Litigation Reform Act of 1995. It should be noted that there are risks and uncertainties related to the development of novel anticancer products, including IMGN901, including risks related to uncertainties around clinical trials conducted and their timings and results. A review of these risks can be found in ImmunoGen's Annual Report on Form 10-K for the fiscal year ended June 30, 2009 and other reports filed with the Securities and Exchange Commission.


Contact: ImmunoGen, Inc.
Carol Hausner, 781-895-0600
Executive Director, Investor Relations and Corporate Communications


Posted: November 2009