Seattle Genetics gains rights to Immunomedics' experimental cancer drug sacituzumab govitecan

Seattle Genetics agreed to license exclusive global rights to develop, manufacture and commercialise Immunomedics' experimental cancer drug sacituzumab govitecan under a deal potentially worth around $2 billion, the companies announced Friday. The antibody-drug conjugate (ADC), also known as IMMU-132, consists of an anti-TROP-2 antibody linked to SN-38, the active metabolite of irinotecan.

Under the agreed terms, Seattle Genetics will make Immunomedics an upfront payment of $250 million, with the latter eligible to receive development, regulatory and sales-dependent milestone payments up to a total maximum of approximately $1.7 billion, as well as tiered double-digit royalties. The companies noted that alongside the transaction, Seattle Genetics is purchasing approximately $15 million of common stock, representing a 2.8 percent stake in Immunomedics.

Commenting on the deal, Seattle Genetics CEO Clay Siegall said "sacituzumab govitecan would complement our existing pipeline by providing a potential near-term opportunity to commercialise a second drug in the [US], expand our international capabilities in Europe and elsewhere and extend our efforts in solid tumours."

Sacituzumab govitecan is currently being studied in a Phase I/II trial for patients with triple negative breast cancer (TNBC), with results intended to serve as the basis for a planned filing under the FDA's accelerated approval regulations.  The drug has received breakthrough therapy designation from the FDA for the treatment of patients with TNBC who have failed prior therapies for metastatic disease.

Immunomedics noted that under the agreement, Seattle Genetics will be responsible for initiating a Phase III study of sacituzumab govitecan in patients with metastatic TNBC. The deal also includes the development of additional indications for the drug, including urothelial cancer, small-cell lung cancer and non-small-cell lung cancer, which are currently in Phase II studies.