Immunogen realized that the critical point in developing ADCs is the linker that conjugates the antibody to the chemo drug. There are plenty of antibodies that target cancer cells specifically as well as plenty of effective chemo agents, but the biggest challenge is gluing them together. Most importantly, for the drug to be safe, the linker must be very stable inside the blood stream. Then, in order for it to be effective, the drug must be released in its active form once inside the cancer cell. It might sound simple in theory but doing it properly is anything but simple, and for that reason, we believe that Immunogen’s proprietary technology is very appealing.
Unlike other groups who develop ADCs, Immunogen does not use traditional chemotherapy drugs such as Taxol and Doxorubicin, but decided to use derivatives of maytansine, which is a much more powerful agent. Because maytansine is such a toxic compound, it cannot be used “as is” due to unbearable side effects. However, when properly linked to an antibody, such a deadly compound may even do a better job killing cancer cells. The derivatives used by Immunogen are patented and can be linked to antibodies via various mechanisms, which should be tailored for each case individually.
Investors should take note of the company’s attractive business model, where it develops its own agents on top of licensing its technology to other companies. In an industry where most products fail, it is crucial for any drug development company to be involved in as many projects as possible in order to reduce the risks involved. Immunogen is engaged in the development of its own ADCs and currently has 2 such agents in clinical trials. In addition, they license their products and technology to other companies such as Genentech (DNA) and Sanofi-Aventis (SNY). Such partnerships usually involve milestone payments of several tens of millions per product, manufacturing and R&D costs coverage and royalties from future sales. A small company such as Immunogen is limited in the resources it can allocate to each clinical program. Therefore, we see such collaborations as an ideal strategy, which enables the development of a large number of candidates based on Immunogen’s technology, with all the development and clinical costs being covered by large partners. Furthermore, the milestone and R&D payments it receives from its partners decreases the need for additional fund raising and dilution, throughout the clinical evaluation process.
Owing to its strategy, Immunogen has an impressive pipeline, with five candidates in clinical development and many more in pre-clinical stages. Notably, only two of the five candidates are exclusively owned and developed by Immunogen (huC242-DM4 and huN901-DM1) with the rest developed and financed by its partners (Herceptin-DM1, in development by Genentech; AVE9633 and AVE1642, in development by Sanofi-Aventis).
Author is long IMGN