Exelixis takes $20m option Iconic/Zymeworks' cancer ADC

Exelixis has taken a $20 million option to license in an antibody-drug conjugate cancer (ADC) drug from Iconic, with clinical trials expected to start next year.

The California biotech had reached an agreement with Iconic and Zymeworks giving the option on the drug in May last year.

Probably best known for the cancer drug Cabometyx (cabozantinib), which is marketed by Ipsen outside of the US and Japan, Exelixis already has four small-molecule drugs on the market.

But CEO Michael Morrissey has selected ADCs as an area of research focus, and announced two partnerships in this field with Swiss startup NBE Therapeutics and Catalent Pharma in September.

After taking the option Exelixis now has responsibility for clinical development, marketing and manufacturing of the Tissue Factor (TF) targeting drug known as XB002.

The drug consists of an antibody targeting TF, coupled with a linker and cancer-killing payload developed by Zymeworks.

Exelixis plans to file for clinical trial clearance with the FDA shortly and plans to take it into a phase 1 trial involving solid tumours early next year.

Exelixis gained an exclusive option to license XB002 (then ICON-2) in exchange for an upfront payment to Iconic of $7.5 million and a commitment of preclinical development funding.

Iconic is now also eligible for future development, regulatory and commercialisation milestone payments, as well as royalties on potential sales.

Zymeworks, based in Vancouver, will also get a share of the option fee and could also receive a share of all future revenue and any sales royalties under an agreement licensing the drug to Iconic.

Exelixis said it decided to take the option after preclinical studies showed that the drug binds to Tissue Factor without affecting the blood clotting cascade, which has held back development of other molecules aimed at the target.

Although it is an important part of the blood clotting process in healthy cells, tissue factor is also expressed by tumours.

It contributes to several of the processes that help cancers grow, including thrombosis, metastasis and growth of blood vessels that feed oxygen to the tumours.