ImmunoGen, Inc. was a biotechnology company focused on the development of antibody-drug conjugate (ADC) therapeutics for the treatment of cancer.

[2] An ImmunoGen ADC contains a manufactured antibody that binds to a target found on cancer cells, with one of the company's potent cell-killing agents attached as a "payload".

The mirvetuximab, which has been submitted for FDA approval, is being developed as a monotherapy or a standalone treatment for ovarian cancer.

Companies licensing ImmunoGen's technology include Amgen, Bayer HealthCare, Biotest, Genentech/Roche, Eli Lilly, Novartis, Sanofi, and Takeda.

[14][15] In October 2015, the company disclosed that Kadcyla had failed to meet its primary endpoint in the Phase II/III GATSBY trial investigating the second line treatment of HER2-positive advanced gastric cancer.