Seattle Genetics has signed a $2 billion deal for Immunomedics’ IMMU-132 – a drug to tackle a notoriously difficult-to-treat form of breast cancer. 

The deal will see Seattle Genetics pay $300 million upfront and another possible $1.7 billion in milestone payments.

Seattle Genetics will also operate IMMU-132’s proposed phase 3 trial and fund the development, manufacturing and commercialisation of the drug.

IMMU-132 (sacituzumab govitecan) is an antibody-drug conjugate that twins a molecule expressed on the surface of triple negative breast cancer (TNBC) cells called TROP-2 to the active ingredient in the cancer drug irinotecan, called SN-38.

TNBC is a particularly aggressive form of breast cancer which, because of its lack of oestrogen, progesterone and human epidermal growth factor-2 (HER2) receptor, cannot be treated with common hormonal therapies.

The drug has received Fast Track Designation from the US Food and Drug Administration (FDA) for the treatment of TNBC as well as orphan drug status for the treatment of patients with small-cell lung or pancreatic cancers.

IMMU-132 is currently in phase 1/2 trials in TNBC, small-cell and non-small cell lung cancers. If successful, the drug could be granted FDA approval by the end of the year.

As part of the deal, Seattle Genetics will also get exclusive rights to the drug in urothelial cancer, small-cell lung cancer and non-small cell lung cancer settings.