The agreement was leveraged in March this year, when the two companies announced plans to jointly work on a Covid-19 vaccine, using the US biotech’s novel mRNA technology.

In extending the collaboration, the partners said they plan to further combine Translate Bio’s expertise and knowledge from more than 10 years of mRNA research and development with Sanofi’s leadership in vaccine research and development.

Under the updated terms, Translate Bio will receive from Sanofi a total upfront payment of $425 million, consisting of a $300 million cash payment and a private placement common stock investment of $125 million at $25.59 per share.

The biotech will also be eligible for potential future milestones and other payments up to $1.9 billion, including $450 million of milestones under the 2018 agreement.

Inclusive of COVID-19 vaccine development milestones, Translate Bio can expect payments of altogether $360 million over the next several years. The company is also eligible to receive tiered royalty payments based upon worldwide sales of the developed vaccines.

Sanofi Pasteur will pay for all costs during the collaboration term and will receive exclusive worldwide rights for infectious disease vaccines.

The partners said they are currently looking at “multiple” Covid-19 vaccine candidates in vivo for immunogenicity and neutralizing antibody activity as they seek to tap a leading asset. The goal is to start a first-in-human clinical trial in the 2020 fourth quarter.