ImmunoGen was founded in 1981 and became a public company in 1989. From inception, we have focused on the creation of targeted anticancer compounds that make use of monoclonal antibodies to deliver cell-killing agents to cancer cells. Over the years, we have gained unparalleled expertise in the field of immunoconjugates - their design, their development, their preclinical and clinical evaluation, and their manufacturing.

The creation of effective immunoconjugate compounds hinges, in part, on the cell-killing agent used. Like others in this field, our scientists started by evaluating marketed chemotherapeutic agents for use as the killing agent. They quickly determined that such an approach was unlikely to be successful, as such agents were not designed for delivery to cancer cells attached to antibodies and do not have the potency required.

At the time, it appeared that only certain plant and bacterial toxins had the necessary potency. Thus, in the 1980s, we developed several immunoconjugates containing a modified form of a highly toxic plant protein called ricin. A risk with the use of a plant protein, particularly when combined with a mouse monoclonal antibody, is that a patient's immune system will recognize the compound as "foreign" (i.e., not native to the patient's body) and produce antibodies to it, removing it from the blood stream before it reaches the tumor. As cancer patients tend to have impaired immune systems, the risk of this response occurring at a clinically-meaningful level was considered to be low, and we evaluated several such immunoconjugates in the treatment of different types of cancers through the mid-1990s. Contrary to predictions, the immune response seen was sufficient to impact treatment success and so we abandoned this approach.

During the 1990s, we aggressively searched for small molecules with the critical potency as small molecules don't elicit an immune response. From this emerged our TAP technology. In 2000, the first company - Genentech - took an exclusive right to use our TAP technology with antibodies to a specific target (HER2). This led to our current business model, which is to develop our own products and help fund our product programs by outlicensing our TAP technology. Seven companies have now licensed access to our TAP technology.

Also critical for success in the immunoconjugate field is the selection of appropriate cancer targets and the creation of quality antibodies to these targets. Over the course of our history, we have established extensive expertise in both of these areas, and have created both immunoconjugate and "naked" (non-conjugated) antibody product candidates. We also have gained unique expertise in functions critical to advancing an immunoconjugate from the laboratory into the clinic, including product formulation, process development and scale-up, and manufacturing.

We believe that interest in immunoconjugate drugs for the treatment of cancer will expand dramatically in the future, and that ImmunoGen has the combination of technology, infrastructure, and expertise needed for leadership in this promising field.