Sanofi is to supplement its vaccine offering with the acquisition of Dynavax Technologies for $2.2 billion in cash, the companies
said
Wednesday.
The deal is the French drugmaker’s largest since it
bought
Blueprint Medicines for $9.1 billion in June.
Dynavax sells an adult hepatitis B vaccine, Heplisav-B, which brought in $90 million in the third quarter of 2025. The California biotech has previously said it expects full-year 2025 revenues of $315 million to $325 million for the shot.
According to Sanofi, Heplisav-B has an advantage over GSK’s established drug in its dosing regimen. Two shots of Heplisav-B are given over one month, whereas Shingrix requires a second dose to be given two to six months after the first, or one to two months later in immunodeficient or immunosuppressed people.
Heplisav-B can therefore provide seroprotection faster than other hepatitis B vaccines, Sanofi said. The vaccine combines the hepatitis B surface antigen with an adjuvant developed by Dynavax. This is a toll-like receptor 9 agonist, designed to boost the recipient’s immune response.
Like Shingrix, it is an intramuscular shot.
Dynavax also has an investigational shingles vaccine, and
said
in August that early Phase 1/2 data suggest the program, called Z-1018, has “comparable immunogenicity” to GSK’s market-leading Shingrix, with more benign safety. The biotech also has experimental vaccines for plague and pandemic influenza in Phase 2, according to its website. It is partnered with the US Department of Defense on the plague vaccine.
In November Dynavax
licensed
Vaxart’s oral Covid-19 vaccine. Vaxart will receive a $25 million upfront fee for the Phase 2-stage pill, and Dynavax will also invest $5 million into the company. It will also hand over $50 million if it wants to push the vaccine into Phase 3.
Fourth buy this year
Sanofi said the $15.50-per-share offer would not affect its financial guidance for 2025. It expects the deal to close in the first quarter of 2026.
Sanofi has bought several companies this year. As well as the deal for Blueprint — which would not have happened were it not for a
dinner meeting in Paris
in April — it
spent
$470 million on Vigil Neuroscience, which has a pill for Alzheimer’s disease in Phase 2.
It also
acquired
UK vaccine startup ViceBio in July, for $1.2 billion upfront.
The deals are partly aimed at decreasing Sanofi’s reliance on its immunological blockbuster Dupixent, which faces possible patent expiry in 2030.
FDA knockback
Less positively, the FDA kicked Sanofi’s approval application for its multiple sclerosis candidate tolebrutinib into the long grass.
The agency issued a complete response letter for the BTK inhibitor, according to a Wednesday
release
. Sanofi was seeking approval in adults with non-relapsing secondary progressive MS.
On Dec. 15 Sanofi
said
that the FDA had delayed a decision on this point beyond tolebrutinib’s PDUFA date of Dec. 28. It added that it expected further guidance from the agency on when a decision might come in the first quarter of 2026.
But the decision seems to have come within the original timeframe after all.
“Today’s FDA decision is a significant and meaningful change in direction from the feedback the agency previously provided to Sanofi. We are very disappointed by the FDA’s action,” said Sanofi R&D chief Houman Ashrafian.
The company plans to working with the FDA to find a path forward for tolebrutinib, Ashrafian added.
