LONDON (AP) — Shares in drug maker Daiichi Sankyo soared after AstraZeneca agreed to pay the Japanese company up to $6.9 billion as part of an agreement to develop and market a potentially "transformative" cancer treatment.

The companies said Friday they will jointly develop trastuzumab deruxtecan and market it worldwide, except in Japan where Daiichi Sankyo will have exclusive rights. Daiichi Sankyo, which designed the targeted cancer treatment, will be responsible for manufacturing and supply.

AstraZeneca CEO Pascal Soriot says the drug "could become a transformative new medicine" for some breast and gastric cancers.

AstraZeneca will pay Daiichi Sankyo Co. $1.35 billion, plus another $5.6 billion if it meets regulatory and sales milestones.

Daiichi shares rose 15.9 percent to 5,100 yen. AstraZeneca fell 6.9 percent to 6,050 pence in midday London trading.