Latham & Watkins and Gowling WLG have taken roles on one of the biggest pharma deals of the year so far, as drug giants AstraZeneca and Daiichi Sankyo collaborate on a $6.9 billion cancer treatment.

The deal will see the global development and commercialisation of Japan-headquartered Daiichi Sankyo's lead antibody drug, trastuzumab deruxtecan. It is designed to help treat a range of cancers including breast and gastric cancer, as well as non-small cell lung and colorectal cancer.

The commercialisation agreement will involve AstraZeneca paying Daiichi $1.4 billion upfront, with subsequent payments of up to $5.55 billion once certain regulatory hurdles are crossed.

Gowling is advising AstraZeneca and has fielded a team led by London-based life sciences head Patrick Duxbury.

Latham is acting for Daiichi with an international team led by Silicon Valley partner Judith Hasko. The team includes fellow U.S.-based partners Kirt Switzer and Mandy Reeves, alongside Brussels partner Hector Armengod and Tokyo partner Nozomi Oda.

It is the latest in a series of big-ticket pharma deals in recent months. Last month, Sullivan & Cromwell, Linklaters and Simpson Thacher & Bartlett acted as German pharmaceuticals giant Merck launched a $5.9 billion hostile takeover bid for U.S. chemicals manufacturer Versum Materials.