Sanofi-Aventis / ImmunoGen Inc.

Solid Tumor Oncology (ADC Platform)

Disease Overview

Antibody-drug conjugates (ADCs) are targeted therapies linking a tumor-selective monoclonal antibody to a potent cytotoxic payload, designed to deliver chemotherapy directly to cancer cells while sparing normal tissue. ImmunoGen's TAP (Tumor-Activated Prodrug, later renamed Targeted Antibody Payload) technology used DM1 and DM4 maytansinoid payloads conjugated to tumor-targeting antibodies — the same chemistry that later enabled Roche's Kadcyla (T-DM1) for HER2+ breast cancer.

ADC Competitive Landscape

In 2005, only one ADC was on the market — Wyeth's Mylotarg (gemtuzumab ozogamicin, AML, approved 2000 then withdrawn 2010 and reapproved 2017). The competitive ADC field was nascent: Seattle Genetics (now Seagen) was developing brentuximab vedotin (later Adcetris) and ImmunoGen and Wyeth/Pfizer dominated linker-payload IP. Genentech, Centocor, Biogen Idec, sanofi-aventis, Millennium, Boehringer Ingelheim, and Abgenix had all licensed TAP technology to specific targets by 2005. Mitchel Sayare, ImmunoGen Chairman & CEO, said: 'We are delighted that the sanofi-aventis Group has elected to extend this research collaboration. The extension enables the two companies to work together for a fourth year to develop new compounds that can potentially generate revenue for ImmunoGen'. Forward-looking close: The Sanofi–ImmunoGen ADC programs ultimately produced isatuximab (Sarclisa, approved 2020 for multiple myeloma — though as a naked antibody, not a TAP) and tusamitamab ravtansine (SAR408701, anti-CEACAM5 ADC), which Sanofi terminated in December 2022 after Phase 3 NSCLC futility, while ImmunoGen itself was ultimately acquired by AbbVie in February 2024 for $10.1B on the strength of Elahere (mirvetuximab soravtansine), validating the maytansinoid platform 19 years after the Sanofi extension.