Drugmaker Sanofi SA 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.

Amunix Pharmaceuticals, based in South San Francisco, CA, is focused on developing masked T cell engagers and cytokines to bring the promise of these potent immune-activating biotherapeutics to patients with solid tumor cancers. The company is leveraging its proprietary XPAT® and XPAC^TM platforms to advance a pipeline of novel drugs that are preferentially activated in the tumor microenvironment and designed to overcome toxicity challenges that have hindered other T cell and cytokine therapies. Amunix's proprietary masking technology has been clinically validated to extend drug half-life with limited immunogenicity.

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.

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 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.