PARIS, Dec 21 (Reuters) - Drugmaker Sanofi SA (SASY.PA) will buy Amunix Pharmaceuticals Inc for an upfront payment of about $1 billion, marking the latest acquisition by the French drugmaker in the U.S. biotech sphere as Sanofi aims to offset COVID-19 vaccine setbacks. Sanofi, under pressure to revive its drug pipeline and eager to overcome setbacks in the COVID-19 vaccine race, added on Tuesday that it will also pay Amunix up to $225 million based on certain future development milestones. "We are excited to rapidly advance Amunix"s promising pipeline and to combine their innovative candidate medicines with complementary molecules in Sanofi"s immuno-oncology portfolio," said John Reed, global head of research and development at Sanofi. Earlier this year, Sanofi said it would buy two U.S. biotechs, Kadmon Holdings and Translate Bio for $1.9 billion and $3.2 billion, respectively. read more The Translate Bio deal has allowed Sanofi to acquire some significant know-how in the field of mRNA technology, which the group is expected to use in a majority of its vaccine-candidates. Earlier this month, Sanofi and GlaxoSmithKline (GSK.L) said they expected data from late-stage clinical trials of its booster dose of their COVID-19 vaccine candidate in the first quarter, instead of this year, marking another delay for the potential shot. read more Reporting by Sudip Kar-Gupta in Paris and Juby Babu in Bangalore; Editing by Shounak Dasgupta