AstraZeneca AZN.L will license experimental drugs for obesity and weight-related conditions from CSPC Pharmaceutical Group 1093.HK and collaborate on additional projects, paying $1.2 billion upfront and up to $17.3 billion more if development and sales milestones are met, the Chinese drugmaker said Friday.

The deal is the latest tie-up between the two pharmaceutical giants, following collaboration in areas such as artificial intelligence. It expands AstraZeneca's investment in the growing obesity market led by Western rivals. The British-Swedish drugmaker has also licensed an experimental weight-loss pill from China's EccoGene.

CSPC shares were down about 10% in Hong Kong after the announcement.

"This reflects the classic 'buy the rumour, sell the news' phenomenon," said Tony Ren, head of Asia healthcare research at Macquarie Capital, adding that investors appeared to be selling the stock's 26% surge since January 2.

The newly licensed drug candidates from CSPC include SYH2082, a "clinical-ready" product, and three other pre-clinical products in its injectable weight-management portfolio, the company said in a filing to the Hong Kong stock exchange.

The agreement covers the development, manufacturing and commercialisation of the candidates. AstraZeneca has been granted a global license, excluding Taiwan, Hong Kong, Macau, and mainland China.

AstraZeneca will also collaborate on four additional new programmes with CSPC, using CSPC's proprietary platforms for sustained-release delivery technology and AI-driven peptide drug discovery.

AstraZeneca and CSPC did not immediately respond to requests for comment on whether the licensing deal was part of a $15 billion investment in China that AstraZeneca announced on Thursday.

-Sherin Sunny and Andrew Silver/Reuters