French pharma giant Sanofi will buy U.S.-based biotech firm Amunix Pharmaceuticals Inc. for an upfront payment of about $1 billion (890 million euros), pointing to the latest acquisition by the company in the U.S. biotech sphere as it targets to offset COVID-19 vaccine disruptions.

"Sanofi will acquire Amunix for an upfront payment of approximately $1 billion and up to $225 million upon achievement of certain future development milestones," the French firm said in a statement on Tuesday.

Immuno-oncology firm Amunix is developing cancer therapies based on cytokines – small proteins that play a role in controlling the immune system – and T-cells, a type of white blood cell.

Its technology could "precisely tailor-deliver medicines to become active only in tumor tissues while sparing normal tissues," said Sanofi research and development chief John Reed.

Its most promising candidate medicine, dubbed AMX-818, is "expected to enter the clinic in early 2022" for trials, according to Sanofi.

Amunix is the latest in a string of acquisitions by the French company, including September's $1.6 billion buyout of U.S. biotech firm Kadmon, which is developing treatments for transplant patients.

It also bought messenger RNA research firm Translate Bio for $2.7 billion.

Sanofi aims to complete its acquisition of Amunix in the first quarter of next year.